Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejj.23-17033

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

The 2022 Hunga Tonga-Hunga Ha’apai eruption generated tsunamis that propagated across the Pacific Ocean. Along the coast of Japan, nearshore amplification led to amplitudes of nearly 1 m at some locations, with varying peak tsunami occurrence times. The leading tsunami wave can generally be reproduced by Lamb waves, which are a type of air-pressure wave generated by an eruption. However, subsequent tsunamis that occurred several hours after the leading wave tended to be larger for unknown reasons. This study performs multi-scale numerical simulations to investigate subsequent tsunami waves in the vicinity of Japan induced by air pressure waves caused by the eruption. The atmospheric pressure field was created using a dispersion relation of atmospheric gravity wave and tuned by physical parameters based on observational records. The tsunami simulations used the adaptive mesh refinement method, incorporating detailed bathymetry and topography to solve the tsunami at various spatial scales. The simulations effectively reproduced the tsunami waveforms observed at numerous coastal locations, and results indicate that the factors contributing to the maximum tsunami amplitude differ by region. In particular, bay resonance plays a major role in determining the maximum amplitude at many sites along the east coast of Japan. However, large tsunami amplification at some west coast locations was not replicated, probably because it was caused by amplification during oceanic wave propagation rather than meteorological factors. These findings enhance our understanding of meteotsunami complexity and help distinguish tsunami amplification factors.

DOI： 10.1007/s00024-023-03332-9

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Other Link： https://link.springer.com/article/10.1007/s00024-023-03332-9/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s00477-023-02379-3

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.78.2_i_283

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.78.2_i_331

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.78.2_i_397

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：Japan Society of Civil Engineers  

In recent years, the design offshore waves has been revised nationwide, and as a result, the design wave will become larger, which will increase the demand of wave-dissipating works. Currently, when estimating the amount of wave overtopping of a seawall in design, there is no choice but to use Goda's overtopping estimation chart, even if the conditions do not match. Matsushita et al. proposed a wave overtopping discharge estimation chart for wave and cover conditions corresponding to the example of implemented construction, but the results were obtained on a gentle slope beach with a slope of 1/30. Since there are many beaches with a seabed slope of 1/10 in Japan, verification on a steep slope beach is also necessary. This study conducted hydraulic experiments on a steep slope beach with the same crown height of the seawall and the wave absorber, and the fully cross-sectional covered type of seawall. The results were compared with those of Goda's chart and the effect of seabed slope was discussed. Furthermore, the applicability of the Integrated Formula of Overtopping and Runup Modeling (IFORM) to a wave-dissipating seawall was examined.

DOI： 10.2208/jscejoe.78.2_i_451

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Publishing type：Research paper (scientific journal)   Publisher：American Society of Civil Engineers (ASCE)  

DOI： 10.1061/(asce)ww.1943-5460.0000690

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.2_i_181

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Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.2_i_151

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.2_i_67

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Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.2_i_13

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.2_i_331

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.2_i_211

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.2_i_919

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Authorship：Corresponding author   Language：Japanese   Publisher：Japan Society of Civil Engineers  

Cognitive dissonance is one of the factors that inhibit evacuation during a disaster. The purpose of this study is to clarify the impact of cognitive dissonance on evacuation by using data obtained from questionnaire surveys on evacuation behavior at the time of the typhoon No. 21 (Jebi) storm surge disaster in 2018. The results of the questionnaire survey showed that few people actually evacuated despite being aware of the possibility of flooding, indicating that cognitive dissonance may have occurred. In addition, we developed a logit model of the choice of evacuation behavior and conducted a quantitative analysis of the impact of cognitive dissonance on evacuation behavior. The values of the parameters estimated by the analysis indicate that people unreasonably underestimated the probability of death or disaster occurrence. Therefore, cognitive dissonance was found to occur during the actual evacuation.

DOI： 10.2208/kaigan.77.2_i_1057

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.1_1

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Authorship：Lead author,　Corresponding author   Language：English   Publisher：Fuji Technology Press Ltd.  

<p>The detailed understanding of tsunami hazard risk using numerical simulations requires a numerical model that can accurately predict tsunami inundation phenomena on land. In such models, the structural effects are indirectly considered using the variation of bottom roughness as a proxy for the differences in building densities. Only a few studies have conducted intermodel tests to investigate tsunami inundation in complex coastal urban cities. During the tsunami analysis hackathon held in September 2020, eight research groups met to have a detailed discussion on the current urban inundation problems. In this study, we conducted an intermodel comparison of the numerical tsunami models, using the data from physical experiments that were performed on a detailed urban model. Our objective was to investigate the necessary conditions of an accurate numerical model based that can ensure high reproducibility and practicality. It was confirmed that the accuracy of topographic data is an important parameter for tsunami inundation simulations in complex urban areas. Based on the computational cost and accuracy, we suggest that a resolution of 1 cm of topographic data is a sufficient condition for tsunami inundation simulations on 1/250 scale model.</p>

DOI： 10.20965/jdr.2021.p0978

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejoe.77.2_i_55

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

There was a couple of researches pointed out that the residents' trust on embankments and sense of safety might influence the decision making of evacuation from the tsunami caused by the 2011 off the Pacific Coast of Tohoku Earthquake. The disaster prevention measures against the Nankai Trough earthquakes and tsunamis are an urgent issue. This study used the data of questionnaire survey conducted in coastal area of Hamamatsu, Shizuoka Japan, concerning on residents' awareness of tsunami disaster and tsunami embankment under construction. Cross tabulations were conducted according to the presence or absence of disaster prevention education. In addition, the structural equation modeling (covariance structure analysis) of evacuation decision making was conducted that took into account the recognition to embankment. The results show that although decreasing the risk perception of tsunami increases residents' trust on embankment and feeling of well protected, the perception of embankment has less direct impact on the evacuation decision making. Furthermore, by observing difference in the evacuation decision mechanism depending on the presence or absence of disaster prevention education was taken, the most effective path among the several paths in which disaster prevention education promotes evacuation was the one that directly raises awareness and understanding of disaster prevention.

DOI： 10.2208/jscejipm.76.5_i_141

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18K18563/

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.1_18

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.77.2_i_1105

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

We propose the coRaL method (a method of incorporating Random phase model into Logic tree approach), which is a probabilistic tsunami hazard assessment method with a high objectivity by reforming the evaluation method of earthquake asperity model and the concept of aleatory uncertainty among the probabilistic methods using logic tree approach conventionally used in Japan. The proposed method is applied to the cities located along the Pacific coast where the tsunami risk due to the Nankai Trough megathrust earthquake is assumed. We show that the proposed method can evaluate the tsunami inundation depth distribution for each return period (e.g., 150 years, 500 years, 1000 years, 2500 years), and for each percentile considering the uncertainty of tsunami hazard assessment even for the same return period.

DOI： 10.2208/kaigan.77.2_i_175

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media Deutschland GmbH  

In Japan, the concept of coastal structure design was drastically changed after the Great East Japan Earthquake. In the design of breakwaters, a "resilient" structure is required to prevent a breakwater from fall over damage due to scouring of rubble mound and seabed by tsunami overflows, by installing an additional rubble mound behind the breakwater. The particle method is useful for numerical simulation of large deformation problems treated in coastal engineering. DualSPHysics is an open-source fluid simulation code based on smoothed-particle hydrodynamics (SPH) method and is capable of dealing with a large number of particles because it can track the behavior of particles using GPUs. Few studies have simulated the movement of armour blocks behind a breakwater during tsunami overflow. This study conducts a numerical simulation to reproduce and clarify the scattering process of the armour blocks on the additional rubble mound behind a breakwater during tsunami overflow using DualSPHysics. The applicability of the numerical model is verified by comparing the performance of two types of armour blocks. The simulation model could reproduce the scattering process by using block data that considers the influence of boundary conditions. The performance diagram of the armour blocks was almost identical to the hydraulic experiment results, indicating the validity of the SPH model. The characteristics of the stability of the armour blocks against tsunami overflow could be clarified by analyzing the fluid force acting on the block.

DOI： 10.1007/s40571-021-00429-7

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Publishing type：Research paper (scientific journal)   Publisher：Coastal Engineering Research Council  

This coastal hazards emphasize the need for engineers to understand the fundamental processes causing damage and the potential of maximum damage in order to design coastal communities with increased resilience to tsunami events. Common methods used to evaluate local conditions caused by tsunamis include post-disaster reconnaissance field surveys, numerical modelling, and laboratory experiments. Behavior of land side tsunami, inundation, is not well known as well as the fluid forcing, fragility characteristics and accuracy of tsunami hazard mapping. This study targets to understand local tsunami behavior in a city scale including complex buildings and improve modelling of tsunami inundation in an urban area. Laboratory experiments are an essential starting point in the investigation of urban roughness effects on wave propagation and maximum pressures in coastal communities. Physical modelling usually uses solitary wave, bore wave, and wave imitating Nankai Trough Earthquake as a tsunami wave.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/-4niVrzXviE

DOI： 10.9753/icce.v36v.currents.14

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.76.2_i_313

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.76.2_i_373

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Springer  

This study estimated the roughness factor of two type wave-dissipating blocks by wave overtopping experiments to calculate the amount of overtopping discharge based on EurOtop. The relationship between the roughness factor γf and surf similarity parameter ξm-1,0 was also examined. Experiments were conducted using a two-dimensional wave flume, and test blocks were GRASP and SEA-LOCK. The experimental conditions were set referring to Bruce et al. (2009). The input wave was random waves having JONSWAP spectrum of γ=3.3. The boundary of ξm-1,0 was set to 4.0, and γf was estimated by the least squares method. The relationship between the overtopping discharge q and the crest height RC was considered. Comparison of γf in cases with different layer thickness showed that the case of γf with large layer thickness was smaller than the γf with small layer thickness' case. The results of Rock and Cube in the experiments by Bruce et al. indicated that the γf value of two-layers was smaller than that of single-layer, the present study was same tendency as existing results. By comparing γf in cases with different structure crest width GC, it was found the case of GC=150 mm was γf =0.36 of which value was about 8% smaller than the case of GC =104 mm. Consequently, it is considered that the γf value of wide structure crest became smaller than that of narrow crest. Under two-layer thickness condition, the roughness factors γf of SEA-LOCK were 15% smaller than the γf of GRASP. The installed volume porosity of GRASP is 63.5% and SEA-LOCK is 53%, GRASP is 10.5% larger than SEA-LOCK. In addition to the difference in block shape, it is thought that the difference in the installed volume porosity of the block also affected the overtopping discharge.

DOI： 10.1007/978-981-15-0291-0_20

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Hasanuddin University Press  

Storm surge risk is basic and important information for design of coastal structure, but its probability assessment is difficult because the frequency of devastating TC is not so high. Furthermore, storm surge damage is very sensitive to not only its intensity but also its track and translation speed. Therefore, the estimation of occurrence probability of devastating disaster from our limited observation data has uncertainty. Recently, we have developed Global Stochastic Tropical cyclone Model (GSTM). The comparison of observation data and simulation results of GSTM showed the reasonable reproducibility of macroscopic statistics of TC parameters such as central pressure, translation direction and speed. However, the verification area of previous study was too large to consider the applicability to risk assessment of local bay scale. Therefore, the microscopic and detailed verification of GSTM is necessary. In this study, we tried to evaluation of reproducibility of TC parameters which was calculated by GSTM at small region as a local bay scale. Furthermore, we improved GSTM by implementation of the cluster analysis of observation data to the process of estimation of the joint Probability Density Function (joint PDF) of temporal correlation of TC parameters. At last of this study, a case study approach by storm surge simulation was performed in order to explain the practical meaning of GSTM. Synthetic TC data based on historical TC track was generated and they were used for input to numerical model for estimating the water height of storm surge at regional scale. Then, the TC track of the worst-case scenario for Yatsushiro bay located in center of west Kyushu Island was decided. Finally, the occurrence probability of the worst-case scenario was calculated from GSTM results.

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.sandf.2019.08.008

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Language：Japanese   Publishing type：Research paper (scientific journal)  

J-GLOBAL

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Publishing type：Research paper (scientific journal)  

© 2019 Japan Society of Civil Engineers. Typhoon Jebi in 2018 caused severe damage along areas of Osaka Bay, Japan. After the storm, a Japan Society of Civil Engineers (JSCE) coastal survey group surveyed the coastal impacts and recorded watermarks inside Osaka Bay and along the Pacific. The maximum storm tide recorded by a tide gauge was 3.29 m at the Osaka Tide Station, which is a historical high for Osaka Bay. Coastal flooding consisted of both storm surge and wave run-up in almost all locations, with flooding exceeding 5 m and 12 m in elevation from mean sea level in the inner parts of Osaka Bay and along the Pacific coast, respectively. Coastal damage was severe in areas located outside of coastal barriers, such as ports and harbors, while residential areas were mainly well protected and spared due to coastal protection systems. In addition, some inland flooding occurred in the Kobe-Ashiya regions due to the storm surge propagating up several small rivers. This survey report summarizes the findings of the post-event survey by JSCE and analyzes the relation between maximum water level and resulting damage.

DOI： 10.1080/21664250.2019.1619253

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：FRONTIERS MEDIA SA  

This study conducted a physical model experiment to investigate inundation processes in a complex coastal city model using the Hybrid Tsunami Open Flume in Ujigawa Open Laboratory (HyTOFU). The physical model was constructed at a 1:250 scale as an idealization of the coastal town of Onagawa. Two tsunami waveforms were used, hydraulic bore and solitary wave, which were produced by a pump-type wave generator and a mechanical piston-type wave generator, respectively, at HyTOFU. Tsunami wave generation similar to the 2011 Tohoku earthquake tsunami in Onagawa was successfully reproduced, and the spatial distribution of the tsunami wave propagation and inundation processes on land was clearly observed. A comparison of experimental and numerical models was performed using two-dimensional (2D) and quasi-three-dimensional (Q3D) models. The 2D and Q3D results agreed well with the experimental results in terms of maximum water surface elevations and arrival times for hydraulic bore conditions. For solitary wave trials, the maximum water surface elevations of the 2D results were underestimated, and the arrival times in the numerical models were slower than those in the experimental results. In this study, as a benchmark for the 2011 Tohoku earthquake tsunami, the dataset of tsunami inundation is provided, which will be useful to validate other numerical tsunami models.

DOI： 10.3389/fbuil.2019.00046

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.75.i_277

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Language：Japanese   Publisher：Japan Association for Wind Engineering  

DOI： 10.5359/jawe.44.288

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3389/feart.2019.00261

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

DOI： 10.2208/kaigan.75.i_283

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Language：English   Publishing type：Part of collection (book)   Publisher：Geological Society of London  

In this study, earthquake rupture models for future mega-thrust earthquakes in the Nankai-Tonankai subduction zone are developed by incorporating the main characteristics of inverted source models of the 2011 Tohoku earthquake. These scenario ruptures also account for key features of the national tsunami source model for the Nankai-Tonankai earthquake by the Central Disaster Management Council of the Japanese Government. The source models capture a wide range of realistic slip distributions and kinematic rupture processes, reflecting the current best understanding of what may happen due to a future mega-earthquake in the Nankai-Tonankai Trough, and therefore are useful for conducting probabilistic tsunami hazard and risk analysis. A large suite of scenario rupture models is then used to investigate the variability of tsunami effects in coastal areas, such as offshore tsunami wave heights and onshore inundation depths, due to realistic variations in source characteristics. Such investigations are particularly valuable for tsunami hazard mapping and evacuation planning in municipalities along the Nankai-Tonankai coast.

DOI： 10.1144/SP456.1

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society of Civil Engineers (ASCE)  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In the event of disaster, the risks of disaster are intertwined, and there is an occurrence possibility of simultaneous damage in multiple areas. This study assesses aggregate risk of storm surge by typhoons which attack Ise and Mikawa bay, and employs synthetic typhoon datasets made by the stochastic typhoon model. Storm surges in Ise and Mikawa bay are calculated by an empirical formula and a nonlinear shallow water equation model. Parameters of empirical formula to estimate storm surge in Mikawa bay is also derived, and applicability is confirmed. The study estimates loss function in Mikawa bay using the results of inundation simulation, and calculates damage using asset map. Event curve is estimated by the relationship of annual exceedance probability and aggregate loss.

DOI： 10.2208/kaigan.73.I_241

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;Shizuoka Prefecture, located on the Pacific side of Japan, anticipates major influence due to the Nankai Trough Earthquake. To evaluate potential hazards and risks due to future devastating tsunamis, coastal defense structures in Shizuoka have been designed against L1 tsunamis (once in about 100 to 150 years) and L2 tsunamis (once in about 1,000 years). However, the current deterministic procedure of deciding upon L1 design tsunamis lacks rigorous consideration and discussion of uncertainties associated with possible tsunami sources. In this study, a new method of determining the design tsunami heights probabilistically, using stochastic tsunami models in the range of <i>Mw</i> 7.8 to <i>Mw</i> 9.0. The stochastic method consists of several calculation steps, i.e. stochastic slip generation, initial tsunami profile determination, and numerical simulation of tsunami propagation. The exceedance probability curves of tsunami heights along the coastline in Shizuoka were estimated and compared with the current estimates based on the L1 tsunami and the L2 tsunami which are published by Shizuoka Prefecture. The results indicate that the current L1 tsunami heights at some locations correspond to return period longer than 200 years (i.e. overrated). To define L1 tsunamis more objectively and consistently, the proposed probabilistic approach is suitable.

DOI： 10.2208/kaigan.73.I_421

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;This study proposes the empirical formula of wave height estimation over reefs in which the coefficients in the formula are determined using simulation results by the Boussinesq wave model that can simulate wave transformation in shallow sea. Seabed slope and gradient are not considered in the past studies, but they are considered by coefficients (&alpha;, <i>B</i> and <i>A</i>) in this study. The applicability of proposed formula was confirmed through comparison with the observations and simulated values by the KP equation model. The proposed empirical formula is able to employ to estimate the design wave height on reefs.

DOI： 10.2208/kaigan.73.I_43

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;Design procedure of coastal embankment compares tsunami height and storm surge height and employs higher value as a crown level. Estimation of tsunami or storm surge height is usually based on the historical maximum record or the assumed maximum value. This study proposes probabilistic evaluation procedure of storm surges employing stochastic typhoon model and applies to Suruga Bay. Typhoon tracks passed the target area were extracted from the synthetic typhoon tracks dataset for 5000 years. Storm surge simulation and inundation simulation were conducted by nonlinear shallow water models, and occurrence probabilities of storm surge height were estimated along coasts in Suruga Bay. Statistical analysis estimated a return period of the current design storm surge height at Suruga coast is about 270 years.

DOI： 10.2208/kaigan.73.I_253

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Empirical tsunami fragility curves are developed based on a Bayesian framework by accounting for uncertainty of input tsunami hazard data in a systematic and comprehensive manner. Three fragility modeling approaches, i.e. lognormal method, binomial logistic method, and multinomial logistic method, are considered, and are applied to extensive tsunami damage data for the 2011 Tohoku earthquake. A unique aspect of this study is that uncertainty of tsunami inundation data (i.e. input hazard data in fragility modeling) is quantified by comparing two tsunami inundation/run-up datasets (one by the Ministry of Land, Infrastructure, and Transportation of the Japanese Government and the other by the Tohoku Tsunami Joint Survey group) and is then propagated through Bayesian statistical methods to assess the effects on the tsunami fragility models. The systematic implementation of the data and methods facilitates the quantitative comparison of tsunami fragility models under different assumptions. Such comparison shows that the binomial logistic method with un-binned data is preferred among the considered models; nevertheless, further investigations related to multinomial logistic regression with un-binned data are required. Finally, the developed tsunami fragility functions are integrated with building damage-loss models to investigate the influences of different tsunami fragility curves on tsunami loss estimation. Numerical results indicate that the uncertainty of input tsunami data is not negligible (coefficient of variation of 0.25) and that neglecting the input data uncertainty leads to overestimation of the model uncertainty.

DOI： 10.1007/s00477-016-1230-x

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;This study conducted a series of hydraulic model experiments using honeycomb structure blocks which possess hexagonal aperture as armour blocks of an artificial reef. The experiments evaluated stability performance of honeycomb blocks and effects of relative water depth <i>h/L</i> to the stability number <i>N_s</i>. The procedure of experiments follows &ldquo;A Manual on Hydraulic Model Test to Evaluate the Stability of Artificial Reef Blocks against Waves&rdquo; issued from the National Institute for Land and Infrastructure Management in 2016. The results clearly show honeycomb blocks have higher stability number <i>N_s</i> than the existing blocks. In addition, <i>h/L</i> has an effect on the stability performance because the smaller <i>h/L</i> is, the smaller <i>N_s</i> is. Furthermore, in case that the relative crown depth <i>R/H</i> is high, the wave transmission coefficient of the artificial reef covered by honeycomb blocks becomes lower than by rectangular blocks. As a result of experiment on the processes of expansion of damage, it occurred from wave breaking point. Honeycomb blocks has remarkable stability performance even in the surf zone where armor blocks are easily lifted up.

DOI： 10.2208/jscejoe.73.I_60

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Experiments were conducted at a 1:20 length scale in a large tsunami flume to measure wave evolution and pressures on and around structural elements. The water surface profiles of waves propagating across a bare beach were compared with those recorded in front of an onshore obstacle representing an urban macro-roughness element. The addition of a structure significantly changed the water surface profile for broken waves: the water surface amplification in the presence of a macro-roughness element reached seven times the bareearth water surface elevation. Estimated pressures from design equations were calculated using recommended inputs and compared with pressures recorded by gauges installed on the structural elements. Design equations showed good agreement for non-breaking wave pressures but underestimated peak pressures for breaking waves. Likewise, force integrations of measured pressures on the experimental specimen indicated that design equations may underestimate loads due to waves that break offshore and propagate across a beach as a turbulent bore. The time-integrated pressure impulse was shown to be less sensitive to wave characteristics than the peak recorded pressures. Time-averaged loading curves were also developed for different average periods.

DOI： 10.1142/S0578563417500048

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Language：English   Publisher：ELSEVIER SCIENCE BV  

The influence of flow velocity on structural damage induced by tsunami inundation is investigated to improve empirical fragility models considering flow velocity as explanatory hazard variable in addition to inundation depth. The analysis is based on extensive tsunami damage data for the 2011 Tohoku earthquake collected by the Ministry of Land, Infrastructure, and Transportation of the Japanese Government. Multivariate tsunami fragility curves are developed through multinomial logistic regression of un-binned data. This approach facilitates the flexible development of various nested models considering inundation depth alone or inundation depth and velocity altogether. Statistical diagnostic metrics, such as the Bayesian Information Criterion, the Akaike Information Criterion, and the residual deviance, are used to determine which model improves the predictability of tsunami damage. The significance and importance of including flow velocity in the vulnerability models are assessed quantitatively by examining the influence of different spatial resolutions in elevation model and different source models. Then, the effects of coastal topography have been investigated. Numerical results show that flow velocity generally improves the fragility models, particularly for severer structural damage states, and that it is important for sites along the coast where the inundation depth is not extremely high. Coarse digital elevation model and inaccurate source models have influence on the calculated values of flow velocity and thus they affect the accuracy of fragility modeling. Finally, two different fragility models are calibrated for plain type and ria-type coasts by reflecting differences in hydrodynamic behavior and recorded damage on the structures. (C) 2017 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.earscirev.2016.12.015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

This paper presents data and analysis for block and boulder transport during Super Typhoon Haiyan along a 4.5 km long, low (5-12 m) cliffed coastline in Calicoan Island, Eastern Samar, Philippines. Wave runup exceeding 15.2 in elevation above mean sea level drove large limestone clasts, with volumes up to similar to 83 m(3), up to similar to 280 in inland. A few very large clasts with volumes 65-132 m(3) were not transported by the waves. When combined with recent transport reported in May et al. (2015), Cox et al. (2016), and other literature, it is becoming increasingly clear that the largest blocks transported by storms overlie much of the tsunami transport range, increasing the difficulty in attributing the transport source without additional evidence. Comparison of present results with a global database of storm boulder transport shows a mass-elevation envelope outside of which no transport is observed.
Initiation of motion criteria were extended to include non-rectangular cross-sections, which significantly reduces inferred velocities, particularly for overturning motion. These new relations were applied to the largest observed sliding and overturning boulders while considering coefficient uncertainties, and resulting velocity uncertainty was large enough that direct inference of wave heights would be problematic. Estimates of initiation velocities for cliff-edge boulders computed using lifting/joint-bounded relations were unreasonably large when compared to those for sliding and overturning boulders, suggesting that processes other than Bernoulli lift forces dominated at cliff edges. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.margeo.2016.11.004

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Publishing type：Research paper (scientific journal)  

DOI： 10.3389/fbuil.2017.00034

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We develop a framework for assessing the sensitivity and variability of tsunami inundation characteristics for stochastic physics-based scenarios of mega-thrust subduction earthquakes. The method is applied to the 2011.Tohoku, Japan earthquake, and tested against observed inundation maps at several locations along the Tohoku coast, using 11 different, previously published, rupture models for this devastating tsunamgenic earthquake. The earthquake rupture models differ in fault dimension (length and width), geometry (dip, strike and top-edge depth), as well as asperity characteristics (slip heterogeneity on the fault plane). The resulting source variability allows exploring a wide range of tsunami scenarios for an MO mega-thrust subduction earthquake in the Tohoku region to conduct thorough sensitivity analyses and to quantify the inundation variability. The numerical results indicate a strong influence of the reference source models on inundation variability, and demonstrate significant sensitivity of inundation to the details of the rupture realization. Therefore, relying on a single particular earthquake rupture model as a representative case when varying earthquake source characteristics may lead to under-representation of the variability of potential scenarios. Moreover, the proposed framework facilitates the rigorous development of critical scenarios for tsunami hazard and risk assessments, which are particularly useful for tsunami hazard mapping and disaster preparedness planning.

DOI： 10.1016/j.coastaleng.2017.06.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Wave experiments were conducted on a 1:20 length scale to measure water surface elevations and extreme pressures on and around idealized structural elements and arrays of structures. Experiments varied offshore wave characteristics and onshore structural configurations. Conditions in which waves broke on or just before the specimen caused maximum impulsive pressures. Pressures measured under nonbreaking wave conditions agreed with predicted values using design equations suggested by the Japanese Cabinet Office; however bare-earth water surface elevation inputs produced nonconservative estimates in breaking wave trials. Shielded structures experienced pressure reductions of 40-70% under breaking wave conditions. Results indicate that shielding elements constructed nearshore may reduce wave-induced damage. This dataset may be used to validate numerical models of tsunami propagation through urban environments. (C) 2016 Published by Elsevier B.V.

DOI： 10.1016/j.coastaleng2016.07.003

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;A statistical model of global wave heights prediction was developed based on the JRA-55 reanalysis data. The previous version of the statistical model estimates global wave heights from wind velocities, sea level pressures and their gradients. This study implemented results from a principal component analysis(PCA) of sea level pressures in the statistical model. The PCA method does better in swell, so the error decreased especially in the area where the previous model failed to estimate wave heights properly. The proposed model significantly improves the underestimation of monthly wave height from local wind and pressure model (the previous model): a positive bias in summer and a negative bias in winter in northern hemisphere.

DOI： 10.2208/kaigan.72.I_139

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;Assessment of aggregate loss becomes important in the Enterprize Risk Management. Municipality usually assesses storm surge damage caused by an expected maximum typhoon, and its procedure does not considers simultaneous damage occurrence in multiple areas. This study develops integrated disaster assessment method of storm surge damage considering simultaneous occurrence in the three major bays: Tokyo, Ise, and Osaka. Stochastic typhoon model enables to estimate probability of typhoon passing through the multiple areas. Nonlinear shallow water model estimates inundation area caused by storm surge and loss on assets in hinterland. Loss function which represents loss and return period of typhoons, and an event curve which represents loss and annual exceedance probability are used for risk assessment. The proposed method shows that aggregate risk is different depend on return period. For the worst class typhoons, the aggregate risk in Ise and Osaka bays becomes larger than the single risk in each bays.

DOI： 10.2208/kaigan.72.I_1639

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;It is important to adequately consider the physical mechanisms of ocean waves to determine the spatial scale and extent of current, temperature and etc in the ocean. This study develops a coupled ocean-wave model to consider wave-current interaction on random waves and analyzes the sensitivity of coastal currents in ideal condition and the Tanabe bay of Wakayama prefecture. The effects of wave-induced transport on random waves are implemented in the ocean model by formulating Stokes drift including random wave spectra. First, the validation of the model was carried out for wave-induced currents having wave diffraction through a slit on constant slope. Second, three runs were carried out for Tanabe Bay of Wakayama Prefecture, considering the Stokes drift effect on random waves and regular waves but not considering the effect of wave-current interaction, to assess the influence of the Stokes drift on random waves. The intercomparison among the results indicated that Stokes drift affected the mean velocity by about 30%, suggesting the Stokes drift effect should not be neglected in the regional circurations.

DOI： 10.2208/kaigan.72.I_511

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;Numerical tsunami simulation can be effective tool for inundation estimation. Numerical models usually employ bottom roughnesses to simulate land use and density of buildings. Since few physical tsunami experiments for complex costal city have been done, local accuracy of inundation depth, area, and force are difficult to discuss. This study conducted inundation experiments using a coastal city model and measured inundation depth, area, velocity, and pressure. Through comparisons of experoimental results with simulation ones, effect of complex topography was discussed. New wave generation system by a paddle and a pump enabled to generate arbitrary and complex tsunami train. The results of inundation depth at reference points show importance of considering land use and building density for using bottom roughness. For runup, long and high building (e.g. station) should be treated as topography instead of roughness. Empirical formula of tsunami pressure underestimates for multidirectional tsunami flooding.

DOI： 10.2208/kaigan.72.I_385

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

New scaling relationships of key earthquake source parameters are developed by uniformly and systematically analyzing 226 finite-fault rupture models from the SRCMOD database (http://equake-rc.info/srcmod/). The source parameters include the fault width, fault length, fault area, mean slip, maximum slip, Box-Cox power, correlation lengths along dip and strike directions, and Hurst number. The scaling relationships are developed by distinguishing tsunamigenic models from non-tsunamigenic models; typically, the former occurs in ocean and has gentler dip angles than the latter. The new models are based on extensive data, including recent mega-thrust events, and thus are more reliable. Moreover, they can be implemented as multivariate probabilistic models that take into account uncertainty and dependency of the multiple source parameters. The comparison between new and existing models indicates that the new relationships are similar to the existing ones for earthquakes with magnitudes up to about 8.0, whereas the relationships for the fault width and related parameters differ significantly for larger mega-thrust events. An application of the developed scaling relationships in tsunami hazard analysis is demonstrated by synthesizing stochastic earthquake source models in the Tohoku region of Japan. The examples are aimed at providing practical guidance as to how the developed scaling relationships can be implemented in stochastic tsunami simulation. The numerical results indicate that the effects of magnitude scaling of the source parameters and their uncertainties have major influence on the tsunami hazard assessment.

DOI： 10.1142/S0578563416500108

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Society of Offshore and Polar Engineers  

Tsunamis generated by earthquakes commonly propagate as long waves in the deep ocean and develop into sharp-fronted surges moving rapidly toward the coast in shallow water, which may be effectively simulated by hydrodynamic models solving the nonlinear shallow water equations (SWEs). However, most of the existing tsunami models suffer from long simulation time for large-scale real-world applications. In this work, a graphics processing unit (GPU)-accelerated finite volume shockcapturing hydrodynamic model is presented for computationally efficient tsunami simulations. The improved performance of the GPU-accelerated tsunami model is demonstrated through a laboratory benchmark test and a field-scale simulation.

DOI： 10.17736/ijope.2016.ak10

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Boulders numbering in the high hundreds/low thousands, and with masses up to similar to 30 tonnes, were transported onshore by Super Typhoon Haiyan in Calicoan Island, Philippines to maximum ground elevations that could exceed 9m and terminal positions up to similar to 180m inland. One-dimensional Boussinesq hindcasts of coastal boulder motion showed intermittent transport initiated at the fronts of infragravity swash bores. Transport distances were found to be highly sensitive to wave-height, enough so that observations of terminal positions may be a viable method of estimating rough paleostorm magnitudes. The large accelerations at bore fronts generated significant inertial forces, particularly for larger boulders, but drag forces had greater root-mean-square magnitudes in all simulations. Widely used relations to infer fluid velocities from boulder properties were tested using modeled boulders - inferred velocities at modeled terminal boulder positions were compared to maximum computed Boussinesq fluid velocities at these locations and found to be significantly lower. This underprediction of inferred velocities was greatest for smaller boulders that were strongly mobile. Inferred drag loads compared to modeled values were somewhat more accurate for large boulders when a Froude number of unity was assumed to estimate flow depths. Although these boulders were unequivocally transported by storm waves, their large sizes and distances traveled venture into what has been considered the tsunami range. Thus, care must be taken to interpret the provenance of coastal boulder fields with unknown origin for lower to mid-latitude regions.

DOI： 10.1142/S0578563416400040

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DOI： 10.17265/1934-8975/2016.03.004

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The present study investigates how the wind speed limited wave dependent drag coefficient (C-D) influences the surge and wave generation of Super Typhoon Haiyan, which struck the coasts of the Leyte Gulf, in the Philippines (2013), using a coupled surge and wave model. In addition, we examine the effect of changes of the radius (R-max which the maximum wind speed occurs. Accurate determination of this radius is crucial to the Haiyan wind and pressure field when using a parametric wind and pressure model because of lack of observation data. The calculation results show that the radius ranges from 40 km to 50 km: as the radius becomes narrower, the surge and wave heights are reduced. Our calculation of surge and wave levels uses a modified version of Janssen' method (Janssen, 1989, 1991) with a step function applied to level off C-D in the exponential wave growth term. In the present method, the wind speeds are limited to a certain threshold; below this value the effective roughness is estimated with a logarithmic wind profile. With the newly modified method, we investigate the effect of the wind speed-limited wave dependent drag C-D for high winds (&lt;70 m/s) on the Haiyan surge and wave levels. When leveling off C-D at 25 m/s for R-max = 50 km good agreement with survey data is obtained in terms of surge level (6.5 m) and wave heights (7 m and 17 m inside and outside of the gulf). The numerical experiments suggest that leveling off at wind speeds of 25-30 m/s results in the accurate prediction of Haiyan storm surge and wave levels in the coupled surge and wave model. The study demonstrates the applicability of the present method of leveling off at wind speeds of 25-30 m/s in a coupled surge and wave model for super typhoon conditions. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ocemod.2015.06.004

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Future change of wave climate depends on greenhouse gas emission/concentration scenarios and GCM models. Future projection of ocean wave climate was conducted by global climate models and a wave model, based on multi-model ensemble experiments. The winter wave heights in the Western North Pacific decrease under global warming corresponding to the West Pacific pattern (WP) change. This result is highly consistent among ensemble experiments.

DOI： 10.2208/kaigan.71.I_1525

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017142661?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The intensity of tropical cyclones due to climate change is projected to be likely increase. Thus, risk of coastal disaster may become severer, and reliable projection of future storm surge change has become more important for coastal disaster mitigations. Although the horizontal resolution of General Circulation Model (GCM) is getting increase to generate tropical cyclones, GCM still has unignorable bias compare to Regional Climate Model (RCM). This study develops statistical bias correction method of typhoon characteristics (track, pressure, and wind speed) projected in GCMs to contribute for more accurate future storm surge projection. Future change in storm surge is projected using the bias corrected typhoons from GCM outputs as a driving force. Ensemble storm surge simulations indicate uncertainty of future change projection of storm surge and necessity of more number of ensemble climate model experiments.

DOI： 10.2208/kaigan.71.I_1507

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017142609?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Crest heights of storm surge barriers and seawalls in Japan are determined based on either by wave runup or overtopping discharge. Technical Standards in Japan also states that the design safety level may differ depending on the selection of wave runup or overtopping as the design criterion. Mase et al. (2013) proposed wave runup and overtopping integrated formula at seawalls constructed on land or in very shallow water. However prediction accuracy is not verified for seawalls constructed in deep water and for vertical seawalls. This study extends the previous model to vertical seawalls based on CLASH datasets. The model is called as IFORM (Integrated Formula of wave Overtopping and Runup Modeling).

DOI： 10.2208/kaigan.71.I_847

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017143774?from=CiNii

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Natural disasters seem to be remarkable recently due to climate change. In these circumstances coastal structures should be maintained and designed so as to be adapted to climate change represented by sea level rise, intensified storm surges and waves. This study examines the design methods how to determine the crown height of coastal dikes where the conventional method and a proposed method are compared. The present method is based on a level III reliability analysis, and the essential point of the present adaptation to climate change is that the present reliability of coastal dikes should be maintained in the future climate.

DOI： 10.2208/kaigan.71.I_1183

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017144450?from=CiNii

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In the Sea of Japan off the coast, sometimes the strong seasonal storm developed rapidly in winter. On the other hand, a few number of typhoons approaches or make landfall in the Pacific Ocean of Japan in summer. These tropical and extra-tropical cyclones give severe damage to coastal areas around Japan. Recent studies have proposed prediction model of expected value of <i>H</i>_max. Although the prediction theory has been validated by numerical model and wave flume experiments, the validation of the theory against field data is not examined well. In this study, characteristic extreme weather disturbances around Japan in the last few years, winter storm occurred in April 2012 and two severe typhoons in 2012 (Sanba) 2014 (Phanfone) are selected for analsys. This study was carried out for estimates of significant wave height <i>H</i>_1/3 and maximum wave height <i>H</i>_max by spectral wave model SWAN.

DOI： 10.2208/kaigan.71.I_457

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017138978?from=CiNii

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Most of breakwaters which were damaged by the 2011 Tohoku tsunami have been reconstructed to withstand the same <i>M_w</i> 9.0 earthquake or smaller intensity. However, as the same tsunami is unlikely to occur, future tsunami defense strategy should consider the variability of tsunami sources. This study investigates breakwater stability against uncertain tsunamis using a stochastic tsunami source model for the 2011 Tohoku earthquake. The analysis of the tsunami profiles in five Tohoku ports demonstrated that the locations and topography of these ports strongly influence the variability of the maximum tsunami wave height. The results of the stability analysis confirm that the breakwater stability in the ports depends on tsunami wave profiles affected by regional features. The key findings from this paper suggest that future tsunami defense policy should take into account uncertainty and variability in tsunami wave profiles and regional features of tsunami amplification.

DOI： 10.2208/kaigan.71.I_895

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017143842?from=CiNii

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study examined long-term wave hindcasts forced by JRA-55 reanalysis released by Japan Meteorological Agency. The wave hindcasts were performed by new version of WAVEWATCHIII 4.18 with two different configurations, ST2 and ST4 forced by sea surface winds of JRA-55. The mean and extreme significant wave heights show good agreement with observed data by buoys and satellite altimeter. The results of wave hindcasts based on JRA-55 performs better than existing wave reanalysis as ERA-40 and ERA-interim. The extreme value analysis for wave heights are agree with observed data in the mid-latitude except active tropical cyclone regions.

DOI： 10.2208/kaigan.71.I_103

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017144269?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Crown heights of seawalls should be designed to suppress overtopping discharge to a permissible level. The permissible level is determined from viewpoints of the structure types of coastal seawalls and hinterland use. It is usually difficult to design the crown heights of seawalls, especially in the present time where climate change due to global warming is expected. This study analyzes climate change effects such as sea level rise (SLR) and increase of waves and surges on the failure probability of seawalls under various conditions of crown height, toe depth and slope by using a Level III reliability analysis. It was found that the difference of SLR trends (fast, medium or low) has less impact on overtopping rates than the differences in wave height change for a seawall at a target location.

DOI： 10.1142/S0578563415500102

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

A computational framework for probabilistic tsunami risk assessment due to a mega-thrust subduction earthquake is developed and is applied to the 2011 Tohoku Tsunami from retrospective viewpoints. The uncertain tsunami source characteristics are represented by multiple source inversion models and their stochastic variations that are generated using the spectral analysis and synthesis method. By conducting Monte Carlo tsunami simulation, stochastic inundation depth maps can be developed, which are subsequently integrated with tsunami fragility curves to develop stochastic tsunami risk maps. The stochastic tsunami risk maps display spatial variability of tsunami damage probabilities for a building portfolio, reflecting not only possible tsunami scenarios but also uncertain tsunami resistance of buildings. The numerical results indicate that both stochastic tsunami risk maps and risk curves are affected by the local terrain features, proximity to major tsunami sources, and building characteristics (material type and story number). Consideration of different reference tsunami source models in probabilistic tsunami risk assessment are identified as one of the critical contributors to the overall uncertainty of the tsunami risk predictions. Therefore, in determining critical scenarios for tsunami evacuation and risk mitigation, a wide range of possible tsunami scenarios should be considered in light of the current limited seismological knowledge for the mega-thrust subduction earthquake.

DOI： 10.1142/S0578563415500151

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study investigated the capability of reproduction for soliton fission propagating over shallow water reef by the extended OpenFOAM. For the three cases with different wave amplitudes and periods, the numerical results by OpenFOAM have achieved very good agreement with experimental measurements. These results have shown that the present OpenFOAM model used in the study has strong ability to simulate tsunami waves and their propagation over shallow water reef. The comparisons with COULWAVE and FUNWAVE simulations have clearly shown that OpenFOAM has achieved much better agreement with experiments. especially for the generation and development of dispersive soliton waves and the reflected short waves.

DOI： 10.2208/kaigan.71.52

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

The sensitivity and variability of spatial tsunami inundation footprints in coastal cities and towns due to a megathrust subduction earthquake in the Tohoku region of Japan are investigated by considering different fault geometry and slip distributions. Stochastic tsunami scenarios are generated based on the spectral analysis and synthesis method with regards to an inverted source model. To assess spatial inundation processes accurately, tsunami modeling is conducted using bathymetry and elevation data with 50 m grid resolutions. Using the developed methodology for assessing variability of tsunami hazard estimates, stochastic inundation depth maps can be generated for local coastal communities. These maps are important for improving disaster preparedness by understanding the consequences of different situations/conditions, and by communicating uncertainty associated with hazard predictions. The analysis indicates that the sensitivity of inundation areas to the geometrical parameters (i.e., top-edge depth, strike, and dip) depends on the tsunami source characteristics and the site location, and is therefore complex and highly nonlinear. The variability assessment of inundation footprints indicates significant influence of slip distributions. In particular, topographical features of the region, such as ria coast and near-shore plain, have major influence on the tsunami inundation footprints.

DOI： 10.1002/2014JC010626

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer International Publishing  

The effects of wave steepness and wave breaking on the stability of wave-dissipating blocks placed on caisson breakwaters are examined by hydraulic experiments under conditions with and without wave breaking. It is confirmed that there is a clear dependence of the block stability on the wave steepness through the wave-breaking type, such as plunging and spilling breakers. The stability parameter in the spilling breaker case is larger than that in the plunging breaker case. For non-breaking wave conditions, there is no effect of the wave steepness. An empirical stability formula is proposed taking into account the effects of the wave steepness and the wave-breaking type. Finally, by using the stability formula, failure probabilities of the wave-dissipating blocks having a nominal diameter are evaluated by the first-order reliability method of the Level II reliability analysis.

DOI： 10.1007/s40722-014-0004-0

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

In the Great East Japan Earthquake, many coastal levees collapsed due to tsunami overflows. In there, concrete-covered levees showed a specific failure mode where back slope blocks and ground were washed out. Although several hydraulic experiments were conducted in order to understand the failure mechanism of concrete-covered levees, it has not yet been clarified especially from the geotechnical viewpoint. The present study examined the failure behaviour of levees due to overflow considering the ground behaviour by the ground model tests. Usage of the centrifuge technique was the key point of this study to reproduce the prototype ground stress and water pressure. The test results showed that the levees collapsed owing to water-flow over the back slope block combined with groundwater seepage.

DOI： 10.2208/kaigan.71.42

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Many issues have been discussed how to reflect the lessons learned from the Great East Japan Earthquake disaster to future earthquake and tsunami disaster prevention measures. Especially ensuring the water cycle network in the macro perspective at disasters and improving water facilities are essential. Realistic policy decisions are required with considering regional requirements, timeline, end-user perspective of water and sewerage services. Thus, municipalities who manage the lifeline of water and sewerage should prepare adjustable disaster response plans considering financial and human resources to ensure quality and quantity of the proper water cycle. This study proposes "strategy for ensuring water cycle network" and discusses matter of concerns which to be considered. A case study targeting Kochi city is conducted and several countermeasures are proposed in this report.

DOI： 10.2208/jscejseee.71.I_915

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

For the tsunami generation in experiments, piston type wave generators with a long stroke are usually employed to make soliton waves representing tsunami in shallow waters. In those ways, a storong flow following the initiall tsunami waves nor local tsunami waves generated in dam-break, mountain-slinding and ice-break. A new tsunami reproducer system has been developed to reproduce such such complecated and tsunami generation mechanism. It composed of three generation modes; 1) Soliton wave generation by piston type wave maker, 2) Generation of tsunami current by sluster-type pumping system, 3) Reproduction of dam-break by overhead tank. The paper descrives the model tests for generated waves by single and composed system operation.

DOI： 10.2208/kaigan.71.I_349

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017141923?from=CiNii

Language：Japanese  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The 2011 Tohoku Earthquake Tsunami showed complex behavior especially in urban areas. To minimize casualties and damage from future events, simulations that can understand the local behavior are required. This study examines a series of numerical simulations by quasi-3D model and 2D model to estimate characteristics of surface elevation and velocity of tsunami in a real city condition. The quasi-3D model agreed well with the experiment on the strait street from shorelines, but it differed with the experimental data at the points behind buildings. The 2D simulation tended to be smaller in comparison with the quasi-3D model because 2D model allows friction to be vertically uniform. There can be large differences of the inundation area between the 2D and quasi-3D models.

DOI： 10.2208/kaigan.71.I_169

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017141459?from=CiNii

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society of Civil Engineers (ASCE)  

The present study aims at the development of after-runner storm surge (ARS) forecast model using an artificial neural network in Sakai Minato and Hamada on the Tottori Coast, Japan, that is made in 30 hours in advance. To develop an artificial neural network-based ARS forecast model, local meteorological and hydrodynamic parameters (surge level, sea-level pressure, depression rate of sea-level pressure and typhoon location of longitude and latitude) on the Tottori Coast are collected. A series of experiments is carried out to improve the ARS forecast model as varying the unit number from 13 to 130. As a result, it was found that the accuracy of ARS forecast model is improved as increasing the unit number. Then, we can obtain the best performance of the ARS forecast model with the given lead time. In addition, the optimal unit number for the given lead time can be determined.

DOI： 10.1061/9780784480304.024

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd  

In the present study, the after-runner surge that maximum surge height appears 15-18 h later along the Tottori coasts facing the Sea of Japan/East Sea (SJES) after typhoons undergo a change in shape and intensity as extratropical cyclones is investigated using asymmetric and symmetric wind and pressure fields of Typhoon Songda (2004). For the asymmetric wind and pressure field, the Weather Research and Forecasting (WRF) model is used, while for the symmetric wind and pressure field, a parametric wind and pressure model is used. The results indicate that both models simulate fairly well the 10 m level wind and the sea level pressure along the Pacific Ocean, while the WRF model shows better agreement with the observations over the SJES. Subsequently, from storm surge simulations for Typhoon Songda, it is found that using the deformed and asymmetric meteorological field of typhoon structures agrees well with observations. The study shows that the after-runner surge's characteristic comes from the Ekman setup in the presence of the Coriolis force over the Tottori coasts. It is critical that its behavior should be taken into account for the safety design of coastal defense structures around the Tottori coastal region.

DOI： 10.1016/j.oceaneng.2014.09.005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER HEIDELBERG  

In this study, we develop stochastic random-field slip models for the 2011 Tohoku earthquake and conduct a rigorous sensitivity analysis of tsunami hazards with respect to the uncertainty of earthquake slip and fault geometry. Synthetic earthquake slip distributions generated from the modified Mai-Beroza method captured key features of inversion-based source representations of the mega-thrust event, which were calibrated against rich geophysical observations of this event. Using original and synthesised earthquake source models (varied for strike, dip, and slip distributions), tsunami simulations were carried out and the resulting variability in tsunami hazard estimates was investigated. The results highlight significant sensitivity of the tsunami wave profiles and inundation heights to the coastal location and the slip characteristics, and indicate that earthquake slip characteristics are a major source of uncertainty in predicting tsunami risks due to future mega-thrust events.

DOI： 10.1186/1880-5981-66-105

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

Typhoon Haiyan, which struck the Philippines in November 2013, was an extremely intense tropical cyclone that had a catastrophic impact. The minimum central pressure of Typhoon Haiyan was 895 hPa, making it the strongest typhoon to make landfall on a major island in the western North Pacific Ocean. The characteristics of Typhoon Haiyan and its related storm surge are estimated by numerical experiments using numerical weather prediction models and a storm surge model. Based on the analysis of best hindcast results, the storm surge level was 5-6m and local amplification of water surface elevation due to seiche was found to be significant inside Leyte Gulf. The numerical experiments show the coherent structure of the storm surge profile due to the specific bathymetry of Leyte Gulf and the Philippines Trench as a major contributor to the disaster in Tacloban. The numerical results also indicated the sensitivity of storm surge forecast.

DOI： 10.1002/2014GL060689

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER METEOROLOGICAL SOC  

A global stochastic tropical cyclone model was developed as a means for preparing a large number of artificial tropical cyclone (TC) samples with different values for parameters such as track, minimum sea level pressure, and translation speed. In this paper, the model and the results of its verification are presented in detail. The proposed stochastic model is sensitive to approximations of the joint probability distribution functions (PDFs) of TC parameters and temporal correlations. A newly introduced accurate method for approximating joint PDFs by using principal component analysis and cluster analysis resulted in improved reproducibility of TC parameters. The simulation results were compared with historical observational data from the northwestern Pacific, southwestern Pacific, and North Atlantic Oceans. The grid-averaged mean values and distribution patterns of PDFs of TC parameters were in agreement with observational data.

DOI： 10.1175/JAMC-D-13-08.1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Japan Society of Civil Engineers (JSCE) and Philippine Institute of Civil Engineers (PICE) jointly collaborated to carry out the field survey on severe storm surge disasters caused by Typhoon Haiyan/Yolanda from 12 December to 16 December, 2013 in Leyte and Samar. Based on interviews with local residents, the joint survey team obtained measured inundation and run-up heights at almost 80 different locations along the coast and also at more than 70 locations inside the cities of Tacloban and Palo. Clear contrast of inundation characteristics was observed especially among east coast of Eastern Samar, inner and southern parts of San Pedro Bay. While inner part of San Pedro bay, as was expected, showed relatively high inundation heights, east coast of Leyte also had comparably high inundation heights even outside the San Pedro Bay. It should also be highlighted that surprisingly high inundation heights were observed along the east coast of Eastern Samar, which faces to the Pacific Ocean with deep Philippine Trench. This paper aims to report primary results obtained through the first joint field survey of JSCE and PICE.

DOI： 10.1142/S0578563414500065

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At 14:46 local time on March 11, 2011, a magnitude 9.0 earthquake occurred off the coast of northeast Japan. This earthquake generated a tsunami that struck Japan as well as various locations around the Pacific Ocean. With the participation of about 300 researchers from throughout Japan, joint research groups conducted a tsunami survey along a 2,000 km stretch of the Japanese coast. More than 5,200 locations have been surveyed to date, generating the largest tsunami survey dataset in the world. The inundation height and run-up height were surveyed by laser, GPS, and other instruments, and the tidal correction has been accurately adjusted using a tidal database and a numerical simulation for Tohoku, an area where tide gauges were destroyed by the tsunami. Based on the survey dataset, the regional and local scale analyses were conducted to understand the basic characteristics of this event. Maximum run-up heights greater than 10 m are distributed along 500 km of coast in direct distance. The affected area of this event was several times larger than historically recorded in Tohoku. The mean inundation height in the southern Sanriku region is 1015 m and there are several peaks of inundation along the coast from the northern to middle part of Sanriku. © 2012 World Scientific Publishing Company and Japan Society of Civil Engineers.

DOI： 10.1142/S0578563412500015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The present study evaluates future storm surge risk due to tropical cyclones (typhoons) in East Asia. A state-of-the-art atmospheric general circulation model (GCM) outputs are employed as the driving force for simulating storm surges associated with the projected changes in climate. The reproducibility of tropical cyclone (TC) characteristics from the GCM in the Northwest Pacific (NWP) is confirmed by comparing with the observed best track data, and future typhoon changes were presented. Storm surge simulation is carried out for East Asia, with the finest nested domain on the Japanese coast. The probability of maximum storm surge heights with specified return periods is determined using extreme value statistics. We show a strong regional dependency on future changes of severe storm surges. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.coastaleng.2013.10.003

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The strong typhoon Sanba crossed the east side of Japan in September, 2012. The minimum central pressure of the Sanba reached 900 hPa. The typhoon generated wind waves more than 15 m in the significant wave height and gave severe damages to coastal structures. This study analyzed observed wave records at 10 stations along the typhoon track. A series of numerical analysis was performed to understand the characteristics of extreme sea condition by the typhoon. The maximum wave heights were estimated based on the spectral wave model and the nonlinear short wave statistical theory. The observed data shows the nonlinear enhancement of maximum wave height slightly. The estimated maximum wave height by the nonlinear theory shows better agreement with the observed peak of maximum wave height than that by the linear theory.

DOI： 10.2208/kaigan.70.I_121

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Other Link： https://jlc.jst.go.jp/DN/JALC/10041328353?from=CiNii

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ICE Publishing  

Recently, caisson sliding failures affected by large waves have occurred. The damage of the breakwaters in Susami port due to Typhoon Tokage on October 2004 is a typical sliding failure and the caissons were tilted down in the rear of rubble mound. The damage at Fushiki-Toyama port on February 2008 is also another typical sliding failure and concrete blocks were settled down. The present paper describes the factors of their caisson sliding failures affected by damage of armor concrete blocks. It concludes that the caisson sliding failure at Susami port was caused by insufficient weight of the caisson. Even if heavier concrete blocks are placed as armors, the caisson would be slid. The numerical simulation suggests that the caisson sliding failure at Fushiki-Toyama port was caused by the combination of three factors of large wave height, long wave period and duration time.

DOI： 10.1680/fsts.59757.0262

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ICE Publishing  

Understanding future changes of storm waves are important for assessing and mitigating the impact of climate on coastal, marine and ocean environments and on engineering problems. Focusing on extreme wave conditions, tropical cyclone activity plays a major coastal force in the tropical to middle latitudes in the summer. Global wave climate projections were performed by the spectral wave model using sea surface winds at 10 m height Uia of the general circulation model (GCM). Extreme values of significant wave height Hs were analyzed by the extreme value analysis for present and future climates respectively. There are clear increases in 50-year return values of Hs in the tropical cyclone dominant regions around the middle latitudes of the Northwest Pacific, the Northeast Pacific and other regions. The influences of future climate change on caisson breakwater are discussed considering sea level rise, extreme wave conditions and storm surges targeted the Pacific side of Japan. The influence of tropical cyclone generated extreme waves is major factor of long-term use of coastal structures in the target area.

DOI： 10.1680/fsts.59757.0204

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DOI： 10.9753/icce.v34.currents.23

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The Coast Act was amended, and in addition to "protection", elements of "environment" and "use" were added. The method of evaluating these three elements objectively and determining a priority to perform suitable coastal preservation in a limited source of revenue has not been developed yet. Thus, this research develops a systematized method using the Analytic Hierarchy Process for the priority assessment of coastal preservation. Five criterions, which are "importance of hinterland", "aging of structures", "use", "economy", and "environment", are employed for the assessment. As a result of using the method, it turned out that evaluation of the priority of coastal preservation in Osaka Bay is possible. Furthermore, it is expectable that more accurate assessment can be performed by using more additional evaluation criteria and detailed data.

DOI： 10.2208/kaigan.70.I_1391

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Other Link： https://jlc.jst.go.jp/DN/JALC/10041328759?from=CiNii

Language：Japanese  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Crown height of a seawall should be designed to suppress overtopping discharge into an allowable level. The allowable level is determined from the viewpoints of the structure type of coastal seawalls and the hinterland use. Since environmental coastal forces, such as sea levels, waves and storm surges, have probabilistic nature, it is usually difficult to design the crown height, especially under the present condition where climate change due to global warming is expected in the future. This study analyzes climate change effects on failure probability of seawalls by using a reliability analysis method of level III and proposes a method to keep the present safety level in the future climate.

DOI： 10.2208/kaigan.70.I_1281

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Other Link： https://jlc.jst.go.jp/DN/JALC/10041328513?from=CiNii

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In local disaster prevention plan, few local municipalities consider unexpected tsunamis, and most of them make a tsunami inundation hazard map following a scenario which is provided by the central government. Hazard map which shows ranges and uncertainties of the assumption can be more reasonable to understand the tsunami risks in the local scale. Local municipalities also should know the disaster resistance capacity of the region in advance to adjust occurrence of unexpected event. This study assesses the resistance capacity of local communities against tsunami inundation by continuous increase in tsunami intensity. The analysis shows the tsunami magnitude which changes the stage of disaster response referring to loss of shelter capacities in the administrative side and the potentially vulnerable and high risk areas against tsunami inundations in the residence side.

DOI： 10.2208/kaigan.70.I_1326

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

There are a lot of researches about momentum exchanges at sea surface which focus on the relationship between wind speed and roughness. Although such researches continue, none of them has explained the roughness under all sea condition. This study evaluates the impact of bulk formulas including wave information on the typhoon simulation using observed results in ITOP. Air side roughness including wave information makes the heat flux from sea to strengthen and influences the wind profile even in the upper air. Typhoon is not affected the air side roughness. The bulk formulas of sea side roughness and TKE flux which is based on wave information estimate smaller current speed and TKE than the formulas based on wind.

DOI： 10.2208/kaigan.70.I_461

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Although a real-time tsunami prediction method which uses observed tsunami waveform as input data for an inversion analysis is effective for non-structural measures, the method needs to wait several-ten-minutes for observed data acquirement. To solve this disadvantage, authors propose the hybrid method which uses not only observed tsunami waveforms but also source rupture process estimated from strong motion seismogram. Unit tsunami source grids for inputs of inversion analysis are selected considering source rupture information. Restraint condition between neighbor unit source grids is employed to estimate the initial tsunami displacement smooth. Effectiveness of additional observation points are discussed to improve the accuracy and reduce the length of input data. The appropriate combination of source rupture process, restraint condition, and additional observation points are effective to improve the accuracy of the real-time tsunami prediction in Tohoku coasts.

DOI： 10.2208/kaigan.70.I_396

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Other Link： https://jlc.jst.go.jp/DN/JALC/10041329527?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Future projection of ocean wave climate was conducted by a spectral wave model using winds from multi-SST and multi-model ensemble experiments of global climate model (MRI-AGCM3.2H). Future changes of extreme waves were investiged under conditions of tropical cyclone (TC) and Non-TC separately. The spatial distribution of future changes in Non-TC extreme waves in global scale were similar to that of mean waves shown in IPCC-AR5. The 10-yr return wave heights under TC condition in the Western North Pacific showed increase or decrease by 4m for different regions. The spatial distribution can be explained by eastward shift of TC.

DOI： 10.2208/kaigan.70.I_1266

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ICE Publishing  

The present study first proposes a random wave runup formula for seawalls installed near shoreline with complex cross section. Then a prediction formula of wave overtopping is developed from the original model of Hedges and Reis (1998) to the case of seawalls near the shoreline including on land. The present formula is used to estimate wave overtopping discharge seen at Ashizaki Nyuzen-machi coastal disaster in 2008 of Toyama Prefecture, Japan, and compared with other existing formulae.

DOI： 10.1680/fsts.59757.0432

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASCE-AMER SOC CIVIL ENGINEERS  

The current study proposes prediction formulas both for random wave runup and mean overtopping discharge at seawalls constructed on land or in very shallow water. Although several existing formulas for runup and overtopping use the incident wave characteristics at the toes of seawalls, this study adopts the equivalent deepwater wave characteristics and an imaginary seawall slope for easy application of the formulas, especially in relation to seawalls constructed on land. The prediction formulas for overtopping use the predicted runup values. For the wave runup prediction formulas two sets of experimental data are used; i.e., a new set of data and the data obtained in a previous study. For the wave overtopping prediction formulas, the experimental data measured in a previous study are used. Comparisons with measurements show good performances of both new prediction methods. (C) 2013 American Society of Civil Engineers.

DOI： 10.1061/(ASCE)WW.1943-5460.0000199

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASCE-AMER SOC CIVIL ENGINEERS  

In Japan, the probability of a Tokai, Tonankai, and Nankai earthquake occurring in the early 21st century is high. Given this likelihood, estimating the resulting tsunami in real time is desirable. This study details an inversion method for real-time tsunami predictions using only observed offshore tsunami data. Numerical experiments demonstrate that (1) the tsunami wave source is estimated fairly well using the inversion method compared with the initial sea surface displacement calculated from the earthquake fault model; (2) the tsunami profiles are predicted with great accuracy at coastal locations of interest; and (3) the profiles are accurately and easily updated using a longer duration of observed tsunami data after an earthquake. This study also investigates techniques to improve the accuracy of the forecasts: screening optimal locations for offshore global positioning system (GPS) buoys, using a longer period of observation data, and decreasing the duration of the tsunami prediction. These techniques illustrate the practical application of this method for tsunami forecasting. DOI: 10.1061/(ASCE)WW.1943-5460.0000159. (C) 2013 American Society of Civil Engineers.

DOI： 10.1061/(ASCE)WW.1943-5460.0000159

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：EARTHQUAKE ENGINEERING RESEARCH INST  

An M(w)9.0 earthquake occurred in the Tohoku-oki area, Japan, at 14:46 local time on 11 March 2011. Tsunamis due to this earthquake were the largest in the recorded history of Japan and caused extensive damage to the eastern coast of Tohoku. In this study, a field survey of damage due to the extremely large tsunamis was carried out for 20 coastal areas along the Iwate and Miyagi Prefectures, focusing on damage to coastal structures and on whether these defense structures were broken completely or failed to perform some measure of tsunami protection. It was found that coastal structures failed locally, rather than entirely along a section of coastline. It is suggested that design conditions for coastal defense structures should be determined by taking into consideration topography, especially low-lying land areas behind structures.

DOI： 10.1193/1.4000122

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：EARTHQUAKE ENGINEERING RESEARCH INST  

At 14:46 local time on 11 March 2011, a magnitude 9.0 earthquake occurred off the coast of northeast Japan. The very large local tsunami heights and damage to coastal structures and other civil infrastructure were strongly dependent on the location. To verify the effectiveness of several types of tsunami protection strategies, we analyzed three typical areas from the Sanriku ria coast. Detailed survey data are shown with photographs and are discussed with regard to severity of damage and tsunami event. The roles of offshore tsunami breakwaters and coastal forests are discussed for severe tsunami, which exceeds 10 m near the coast. The survey observations and results from numerical calculations clearly indicate the reduction of tsunami damage due to an offshore barrier in Kamaishi Bay.

DOI： 10.1193/1.4000118

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This study shows projections of present and future wave climate, typhoon and storm surge using the data of high-resolution atmospheric General Circulation Model and with numerical models of global wave simulation, stochastic typhoon simulation and storm surge simulation.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.69.i_126

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd  

This study analyzes future changes in average upper ocean physics such as sea level rise, sea surface winds and ocean wave heights by using a climate data set combining IPCC (2007) results and the latest high-resolution atmospheric general circulation model results from the Meteorological Research Institute, Japan. Ocean wave height Hs is statistically projected by using multi-model ensemble method based on an empirical formula as a function of sea surface winds. The ensemble means and the standard deviations of upper ocean physics, which can be used in coastal and ocean engineering, are projected for the period between 2000 and 2100. The magnitude of the ratio of future changes in Hs to the value in the present climate is at most ±15%, which exceeds the projected changes in sea surface pressure and surface wind speed, U10. A large uncertainty in the projected Hs can be observed around the Equator and in the Antarctic Ocean. The synoptic scale of atmospheric pressure distribution is found to be important for estimating and understanding the future changes in sea level rise, U10 and H s. © 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.oceaneng.2013.02.016

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

The shape of blocks favorable for their stability against wave action was analyzed from the viewpoint of "space occupancy ratio in a cuboid" for existing blocks. A new high stability block was proposed in this study, which has the shape with three legs at both ends of the axis. Hydraulic experiments were conducted to examine the block stability. A stability number formula was determined from the experimental results. Required weight of the proposed high stability block against design waves is almost the same as a typical high stability block due to the effective interlocking between the blocks. Proposed high stability block is able to decrease the required number and contribute to the cost reduction since the porosity among the blocks becomes large.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study conducted hydraulic experiments to clarify effectiveness of reinforcement for breakwater stability against abnormal tsunami which exceeds the expected level, seen in the Great East Japan Earthquake Tsunami on 11 March, 2011. Though increasing the width of counter mounds reinforcement can reduce displacement of breakwaters, increase of the height of reinforcement is simulteaneously needed against abnormal tsunami. The resilience of breakwaters differs even if the safety factors of breakwaters are the same for tsunami. The formulas to evaluate the horizontal displacement of breakwaters based on their safety factors against tsunami were proposed from the experimental investigation.

DOI： 10.2208/jscejoe.69.I_473

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study deals with the influences of occurrence frequency of high waves on estimation of life cycle cost for a breakwater covered with wave-dissipating blocks using Monte Carlo simulation. The life cycle cost is defined as sum of an initial construction cost and a repairing cost of wave-dissipating blocks. In the computation of the life cycle cost, an occurrence frequency of high wave is assumed as once a year and is determined on the basis of statistical characteristics obtained from wave observation data. As analysis results of high waves at four stations in NOWPHAS, the cumulative frequency distribution for annual occurrence numbers of high waves can be approximated by the Poisson distribution. In the computation of the life cycle cost, the random numbers obtained from the Poisson distribution are used to determine the annual occurrence number of high waves. The optimum size of block that minimizes the life cycle cost is same in most cases regardless of the occurrence frequency of high waves, however, the variability of the total repairing cost during the in-service period is different depending on the occurrence frequency.

DOI： 10.2208/jscejoe.69.I_173

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.69.i_511

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd  

Settlement of wave-dissipating blocks in front of caisson is caused by displacement and breakage of blocks directly by wave action and also by sliding of the caisson by wave force. The settlement of blocks, caisson sliding and wave pressure are mutually correlated. The present study has developed a stability analysis method for a composite breakwater with wave-dissipating blocks under the circumstances of climate change effect as seen in sea level rise and increase in storm surges and waves. It is found that the changes of expected caisson sliding distance and necessary caisson width, determined from the allowable excess probabilities for three prescribed sliding distances, against the weight of wave-dissipating block have a tendency to be maximum at certain block weight when repairing of damaged blocks is not done
on the other hand, if repairing is done every time after reaching 5% damage level of the total section, the changes of caisson sliding distance and necessary caisson width against the block weight show monotonous decrease. The effects of climate change on the sliding distance and necessary width are found to make those values larger by 10-60% than those calculated by constant external forces given from the present climate conditions. © 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.oceaneng.2012.12.037

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

The field survey results obtained by the team of authors in the north of Miyagi Prefecture between April 1 and 6, 2011 are summarized referring to a part of the survey results by other teams of the 2011 Tohoku Earthquake Tsunami Joint Survey Group. The inundation height above sea level was measured using a laser range finder with a reflection prism. The inundation height was generally larger at bay heads, as well as promontory tips, except several points, which were sheltered by a peninsula or had a tapering area. The tsunamis reached inland far away from the sea along valleys and rivers. Not only steel frame buildings but also many reinforced concrete buildings were collapsed in Onagawa Town. According to the numerical results, the first of tsunamis from the west coast and the second of tsunamis from the east coast should come together in Utatsusaki Peninsula, which is consistent with the interviews to survivors.

DOI： 10.1142/S0578563412500076

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Next future Tokai-Tonankai-Nankai earthquake is predicted by the Headquarters for Earthquake Research Promotion with a high probability of more than 60%. This study has evaluated the inundation risk against various tsunami magnitudes over the estimated tsunami source by the Central Disaster Prevention Council. In the Wakayama Prefecture, variation of tsunami-induced inundation areas and heights depends on each area's topography. Inundation risks in the middle and south areas gradually increase with the increase of tsunami magnitude, while the inundation risks in the north low-lying areas increase drastically.

DOI： 10.2208/jscejoe.68.I_156

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study developed an interactive information system that provides wind and wave prediction for offshore wind farms and other ocean activities. High wind during wind turbine operation could lead to damage of rotor blades requiring two to three days offline during repair. Long range wind and wave forecast one week in advance is necessary to successfully schedule turbine operation and maintenance. Short range detailed informational forecast one day in advance ensure worker safety on location as well as during commutes to and from the floating wind farm sites. The present information system gives information for user selected areas and lead times with both visual animations and also time series graphs.

DOI： 10.2208/jscejoe.68.I_1204

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study estimates a sliding distance of a caisson covered with blocks considering the effects of coastal climate change, such as changes in the sea level, storm surge, and wave height. The sliding distance increases in 100-350 % influenced by the change of those factors at the end of 21^st century, depending on the condition of breakwater, compared to that in the present climate condition. The climate change effects on a sliding distance and a necessity width depend on not only the assumed wave height but also the wave height to water depth ratio. The climate change effects become more significant especially for a breakwater installed in a deep water.

DOI： 10.2208/jscejoe.68.I_276

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

At 14: 46 local time on March 11, 2011, a magnitude 9.0 earthquake occurred off the coast of northeast Japan. This earthquake generated a tsunami that struck Japan as well as various locations around the Pacific Ocean. With the participation of researchers from throughout Japan, joint research groups conducted a tsunami survey along a 2000 km stretch of the Japanese coast. More than 5300 locations have been surveyed to date, generating the largest tsunami survey dataset in the world. On the Sendai Plain, the maximum inundation height was 19.5 m, and the tsunami bore propagated more than 5 km inland. Along the ria coast from about 50 to 200 km north of Sendai, the narrow bays focused the tsunami waves, generating the largest inundation heights and run-ups. The survey data clearly show a regional dependence of tsunami characteristics. Citation: Mori, N., T. Takahashi, T. Yasuda, and H. Yanagisawa (2011), Survey of 2011 Tohoku earthquake tsunami inundation and run-up, Geophys. Res. Lett., 38, L00G14, doi:10.1029/2011GL049210.

DOI： 10.1029/2011GL049210

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASCE-AMER SOC CIVIL ENGINEERS  

This study examined the validity of using an artificial neural network (ANN) to predict tsunami water levels at several locations in Osaka Bay. The metropolitan areas of Osaka Bay have short warning times for tsunamis; a real-time tsunami forecast will allow for improved evacuation plans and will reduce the effect of these coastal disasters. Different tsunami conditions changing the relative strength of the asperities and background sources, such as fault displacement, fault length, fault width, fault slope, depth from sea bottom, and strike, were used for training the ANN; the data sets were generated by applying the nonlinear shallow water wave equations assuming different earthquake fault models. The linear activation function produced optimal results for the ANN output units, and the tangent-sigmoid function yielded good results for the ANN hidden layer units. The Levenberg-Marquardt method with Bayesian regulation was employed for the training of the ANN. Output from the trained ANN was the preliminary and secondary tsunami waves; these ANN output data agreed well with numerically obtained tsunami simulation results. DOI: 10.1061/(ASCE)WW.1943-5460.0000092. (C) 2011 American Society of Civil Engineers.

DOI： 10.1061/(ASCE)WW.1943-5460.0000092

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Language：English   Publishing type：Research paper (international conference proceedings)  

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DOI： 10.2208/kaigan.67.i_1181

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Wave set-up in storm surges is studied using a numerical model for coasts in Tosa Bay, Japan, open to the Pacific Ocean. Simulation models employing only atmospheric pressures and winds as external forces are unable to properly simulate open coast storm surge heights, such as those due to Typhoon Anita (1970). However, the present study shows that a numerical model incorporating wave-induced radiation stresses, as well as wind stresses and pressure gradients, is able to account for the open coast surge heights. There is a maximum contribution of 40% by the radiation stresses to the peak sea level rises. This study also evaluates the effects of the tides; including the tides improves the agreement between the predicted water surface elevations and the observations. The difference in predictions between one-way coupling from wave to surge models and two-way coupling of the surge and wave models is found to be small. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.coastaleng.2010.02.004

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Language：English   Publisher：ASCE-AMER SOC CIVIL ENGINEERS  

DOI： 10.1061/(ASCE)0733-950X(2008)134:3(187)

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Language：English   Publisher：Japan Society of Civil Engineers  

A model of predicting coastal currents under non-stationary meteorological and wave conditions is eveloped. The current prediction model is composed of meteorological reanalysis data, a meso-scale weather prediction model and a coupling wave and surge model. The model is applied to the Joetsu Coast for predicting coastal currents and the predictions are compared with observations. The prediction model is also extended to statistically modeled time series of winds and waves. It has been found that coastal currents calculated by the prediction model depend strongly on ocean wind.

DOI： 10.2208/kaigan.66.321

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Other Link： https://jlc.jst.go.jp/DN/JALC/00358854027?from=CiNii

Language：English   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

This study presents a stochastic typhoon model (STM) for estimating the characteristics of typhoons in the present and future climate conditions. Differences between statistical characteristics of present and future typhoons were estimated from projections by an Atmospheric General Circulation Model (AGCM) under a climate change scenario and are taken into account in the stochastic modeling of future typhoons as a climate change signal. From the STM results which utilize the Monte Carlo simulation, it was found that the frequency of typhoon landfall in Japan, especially in three major bay areas, will decrease and the mean value of typhoon central atmospheric pressure will not change significantly. An important point is that the arrival probability of stronger typhoons will increase in the future climate scenario.<br>

DOI： 10.3178/HRL.4.65

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Language：English   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

The influence of global climate change due to greenhouse effects on the earth&rsquo;s environment will require impact assessment, mitigation and adaptation strategies for the future of our society. This study predicts future ocean wave climate in comparison with present wave climate based on the atmospheric general circulation model and global wave model. The annual averaged and extreme sea surface winds and waves are analyzed in detail. There are clear regional dependences of both annual average and also extreme wave height changes from present to future climates. The wave heights of future climate will increase at both middle latitudes and also in the Antarctic Ocean, with a decrease at the equator.<br>

DOI： 10.3178/HRL.4.15

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Language：English   Publisher：Japan Society of Civil Engineers  

The present study validates real-time wave prediction by using wind forcing from hourly analysis GPV during the typhoon season of Japan. Large variations in weather fields occurring in typhoon events provide an opportunity to assess the quality of forecasts. Observed data at 16 NOWPHAS wave gauge stations were used to evaluate predictions during the typhoon season. Deterministic statistic error indices showed that real-time predictions give good results. In addition, probabilistic statistic error indices that can evaluate errors in detail also showed that the correspondence between predictions and observations is good.

DOI： 10.2208/kaigan.66.161

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

The study investigates abnormal surges occurred with time lags to typhoon's peak at west coasts along the Sea of Japan To examine the abnormal Surge due to Typhoon Songda in 2004 the Surge simulations are carried out using different input forces of winds and atmospheric pressures The response of abnormal surges to the effects of terrain and meteorological fields is also examined The results indicate that using output from meso-scale weather prediction model successfully reproduces the abnormal surges occurred with time lags of 15 hours.

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DOI： 10.2208/kaigan.66.1231

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Since major driving forces of storm surge are pressure depressions and wind stresses, a set of depth integrated equations is widely used for storm surge simulations. However, there are several phenomena which should be take into consideration additionally. This study estimates effects of wave radiation stress, vertical mixing and turbulent flux for 3D storm surge model. The effects of revised radiation stresses in the sigma coordinate and wave directional spread are evaluated into the numerical model. The numerical results give significant influences of the wave radiation stress and the turbulent flux on the surface elevation and the current in the stormy condition.

DOI： 10.2208/kaigan.66.306

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Language：English   Publisher：Japan Society of Civil Engineers  

The height of seawall is determined based on allowable wave overtopping rate or wave runup height for the design of surge and wave prevention facilities. Although a design method based on wave overtopping rate takes into account of wave randomness, a design method based on wave runup height does not consider the wave randomness but uses equations and figures obtained from regular waves. Therefore, a unified prediction formula for random wave overtopping and runup is required for establishing the design scheme of seawalls. This study proposes prediction formula for random wave overtopping discharge including wave runup for seawalls with composite cross section installed near shoreline.

DOI： 10.2208/kaigan.66.926

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00358855369?from=CiNii

Language：Japanese  

CiNii Books

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Language：English   Publisher：Japan Society of Civil Engineers  

A flapgate breakwater is a new type structure that usually lies down on the seabed and rises up as a seawall with its buoyancy when tsunami or storm surge occurs. In our previous studies, the characteristics of the flapgate motion and wave pressure were clarified through a series of hydraulic model experiments, and a numerical model that can deal with fluid-structure interactions for the flapgate employing the overset grid method and the level set method was developed for a solitary wave representing a tsunami. In this study, the numerical model was extended to the cases of flapgate motion analysis against periodic waves, and simulation results were compared with experimental ones. It is shown that the numerical model gives accurate predictions of flapgate motions and provides useful information for the design of different size flapgates and wave conditions.

DOI： 10.2208/kaigan.66.811

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00358855116?from=CiNii

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Language：Japanese   Publisher：土木学会  

This study predicts future ocean wave climate in comparison with present wave climate based on the high-resolution atmospheric general circulation model and global wave model. The annual average and extreme sea surface winds and waves are analyzed in detail. There are clear regional dependence of annual average and extreme values from present to future climate. The wind speeds and wave heights of future climate are increased in middle latitudes and the Antarctic Ocean, and these are decreased in the equator. The annual average winds and waves are decreased off coast of Japan but their maxima are increased than those of present climate.

DOI： 10.2208/kaigan.65.1271

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Language：English   Publisher：Japan Society of Civil Engineers  

The present study examines the prediction accuracy effects of 4-dimensional data assimilation (nudging) and nesting schemes of the Weather Research and Forecasting model (WRF) on the storm surges. Applying both nudging and nesting in the WRF simulation enabled us to predict successfully not only the barometric depression and increase of wind speed around a typhoon route, but also the meteorological field of surrounded area. It has been found that the use of WRF outputs applying both with nudging and nesting would give accurate predicting power for both maximum level and phase of tidal elevation in the storm surge simulations.

DOI： 10.2208/kaigan.65.381

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00347681924?from=CiNii

Language：English   Publisher：Japan Society of Civil Engineers  

At Sakai-Minato port around west coast of the Sea of Japan, abnormal storm surges have been measured with timing lags of 15 hours after landfall of typhoons. The present study examines the abnormal storm surges due to Typhoon 0314 and 0418 using the SuWAT (Surge-Wave-Tide coupled model) in different meteorological conditions by the WRF (Weather Research and Forecasting model) and an empirical typhoon model proposed by Fujii and Mitsuta. The results of simulations indicate that the abnormal surges forced by the WRF outputs show good agreement with the measurements. Also, this study describes mechanism why the abnormal surges with time lag are generated due to typhoons at the Sakai-Minato Port.

DOI： 10.2208/kaigan.65.376

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00347681917?from=CiNii

Language：Japanese  

CiNii Books

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Language：English   Publisher：Japan Society of Civil Engineers  

A flap gate breakwater is a new type structure for coastal disaster reduction; the breakwater usually lies down on a seabed and rises up through sea surface with buoyancy when tsunami or storm surge occurs. In past studies, it has been confirmed that the flap gate breakwater has capabilities against tsunamis. The characteristics of wave pressure acting on flap gate are different from those on a fixed gate and a breakwater since the flap gate moves according to acting waves or tsunamis. The present study examined the characteristics of wave pressure acting on the flap gate by hydraulic experiments using monochromatic waves and tsunamis. It was confirmed that the gate motion and wave pressure were closely related, and wave pressure was reduced by employing fluid resistance plates.

DOI： 10.2208/kaigan.65.806

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00347682778?from=CiNii

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Web of Science

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Language：English   Publisher：Japan Society of Civil Engineers  

Stochastic typhoon simulation, that is the combination of the Monte Carlo simulation on typhoon parameters, the storm surge simulation with the parameters, and the extreme-value analysis on the storm surges, is one of useful tools in the probabilistic discussion on the current design storm water level for coastal defense. This paper compares the extreme storm surges on the Pacific coast from Kyushu to Kanto District, Japan, with two empirical parametric typhoon wind field models, two sea surface drag coefficients for high wind speed, and two assumptions of future typhoon change. The result shows that the extreme storm surge is very sensitive to the sea surface drag coefficient for high wind speed and that one of the assumptions gives larger extreme storm surges in some of the coast and smaller in others.

DOI： 10.2208/kaigan.65.1256

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Language：English   Publisher：Japan Society of Civil Engineers  

A series of data set of ocean wave records from the Pacific Ocean and the Sea of Japan is analyzed for understanding freak wave characteristics in lights of wave height statistics, frequency and directional spectrum parameters, and nonlinear statistical parameters. In addition, measured maximum wave heights are compared with predicted ones by a nonlinear wave theory, and the relation of freak wave occurrence with weather condition is made. It was found that observed data shows a weak correlation between maximum wave heights and kurtosis of free surface elevation and that freak waves at peak of storm are observed under migratory low atmospheric pressures.

DOI： 10.2208/kaigan.65.141

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Web of Science

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Language：English   Publisher：Japan Society of Civil Engineers  

Wave climate was investigated for impact assessment and adaptation strategy for coastal hazard area. Related studies show regional dependence; in some regions wave heights increase these 30 years and in some areas decrease. This study examined a long-term variability of annual large waves, such as maximum, top three averaged and top five averaged waves, along coasts of the Sea of Japan using observed wave data. When waves generated by winter monsoon pattern were considered, the wave heights increased in northern area of Japan. The relation between the variations of maximum wave heights and three meteorological indeces was examined; however, there was no clear correspondence between them.

DOI： 10.2208/kaigan.65.1251

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Web of Science

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

This study examines the effects of tides on surges, wave setups and waves, in terms of tidal amplitudes and phases, by using a coupled numerical model of Surge, WAve and Tide (called as SuWAT). The SuWAT model, composed of depth integrated nonlinear shallow water equations and Simulating WAves Nearshore (SWAN) model, is able to simultaneously run with an arbitrary number of nested domains by using the Message Passing Interface. The results for an idealized case indicate that surge and wave setup are increased in the phase of low water and decreased in the high water phase; on the other hand, waves change in a reverse manner. Such changes are enhanced by large tidal variations. The conventional method (e.g., surge plus tide independently) has the possibility of overestimation for the total water level. The hindcast results for Typhoon Ewiniar in 2006 show that the run with tides is more accurate 10% than that without tides in coastal areas of Korea. The nested scheme improves the accuracy up to 40% for the prediction of water levels in the simulations. It is shown that the present coupled model, SuWAT, is capable of predicting both water levels and waves under storm events with reasonable accuracy against the observations. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apor.2009.02.003

Web of Science

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Publisher：Japan Society of Civil Engineers  

This study developed a real-time wave prediction system by using SWAN (Simulating WAves Nearshore) with the data of hourly analyzed atmospheric GPV (Grid Point Value). The validity of this system was carried out by comparing the predictions with observations from NOWPHAS (Nationwide Ocean Wave information network for Ports and HArbourS) during one month of December, 2007. The predicted wave heights and periods well corresponded to the observed ones. By using this system, wave situations at present and short-term future can be estimated for locations where there are no wave observation equipments.

DOI： 10.2208/proce1989.55.186

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00368614666?from=CiNii

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

A set of experiments was conducted to examine the stability of new type of wave dissipating blocks. It was confirmed from the experimental results that offshore wave steepness influences the stability of blocks. The parameters of stability number formula were derived with classification of wave steepness. Required weight of new block against a design wave can be reduced to 90 percent compared to a typical standard block because the stability is being improved. The wave steepness relates deeply to the breaker type, and wave steepness' effect should not be neglected in the stability estimation of blocks. In order to separate the effects of wave steepness and wave breaking, it had better to conduct the experiments with flat bottom condition for further investigation of blocks' stability.

DOI： 10.2208/prooe.24.519

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Geometrical coastal line in big maritime cities is usually complex, since there are many reclaimed lands, many rivers and canals flowing into the sea. For such complex sea area, fine mesh scale is required for the estimation of tsunami propagation and deformation, resulting in increase in the computational time and cost. In this study, a new calculation method, called the Cartesian cutcell method, is used for predicting tsunami propagations and the numerical results are compared with the experimental observations. In the Cartesian cutcell method, the finer mesh is not required even for the complex geometrical coastal shape.

DOI： 10.2208/prooe.24.81

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Language：Japanese  

CiNii Books

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Publisher：Japan Society of Civil Engineers  

A modeling method of long-term time series of waves and winds for evaluation of beach profile change was proposed. Statistical properties of parameters, representing storm waves, were analyzed and theoretical distributions were obtained together with correlations between those parameters. To check the uniformity of waves, meteorological and wave simulations were carried out. Those predictions were compared with the observations at the Naoetsu Port, and found to be well agreed each other. It was concluded that since spatial distribution of waves is uniform along the Joetsu Coast, the statistical variables can be given as input parameters for the concerned area.

DOI： 10.2208/proce1989.55.426

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00368615199?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/proce1989.55.156

CiNii Books

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Publisher：Japan Society of Civil Engineers  

High wave with long wave period, which is known by local residents as "Yorimawari-Nami", hit the east coast of Toyama Prefecture on February 24, 2008. The high wave, in particular, caused huge human and property damages in Ashisaki district of Nyuzen town. The purpose of this study is, at first, to examine coastal damages induced by the swelllike wave throughout filed surveys. The characteristics of high wave deformation, wave overtopping of a gentle-slop type revetment and inundation flow in the residential area are, furthermore, discussed by performing wave hindcasting with a GFS-WRF-SWAN coupled model and numerical simulation on wave overtopping of the revetment in Ashisaki district using a two-dimensional numerical wave flume "CADMAS-SURF".

DOI： 10.2208/proce1989.55.151

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Publisher：Japan Society of Civil Engineers  

This paper uses reliability analysis to estimate the failure probabilities associated with wave overtopping of both sloping and vertical seawalls. Failure probabilities are obtained for different freeboards and permissible overtopping rates, using Monte Carlo simulation for calculations at Level III and the First Order Reliability Method for Level II calculations. The sensitivity of the performance function to the various external random variables is also investigated inorder to establish the relative importance of these variables in influencing the failure probabilities.

DOI： 10.2208/proce1989.54.891

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Publisher：Japan Society of Civil Engineers  

This study examines the validity to use an artificial neural network (ANN) for the prediction of tsunami magnitudes at several locations in the Osaka Bay by using observed water surface elavations of 20 minumites, at the tower of Shirahama Oceanographic Observatory. The tsunami data used as training and test data for ANN were simulated for different fault models considering tsunami source non-uniformity. The linear activation function was found to be a good choice for output units and the tangent sigmoid function for hidden layer's units. For the training of ANN the Levenberg-Marquardt method with Bayesian regulation were employed. Outputs from the trained network such as the first and the second sea surface falls and rises agreed well with the results of tsunami simulations at each location and all five locations.

DOI： 10.2208/proce1989.54.201

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Publisher：Japan Society of Civil Engineers  

The present paper has discussed how to improve our real-time tsunami prediction method by the inverse analysis of tsunami profile observed at offshore points. The inverse analysis of the offshore tsunami data estimates the initial displacements of water surface in the segmented tsunami sources. The estimated initial displacements predict tsunami profiles at inshore points of interests. Our prediction method is tried to improve by the introduction of correlation factors with surrounding segmented sources, the supplement of another observation point, or the employment of wider segmented source area. The paper also confirms that the real-time prediction can be applied to predict the tsunami at Shimotsu Port in Wakayama Prefecture as well as in Osaka Bay.

DOI： 10.2208/proce1989.54.196

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Tokai, Tonankai and Nankai earthquakes are predicted to generate great tsunamis which will attack the Pacific Coasts. The tsunami will arrive at the coasts within ten minutes after the shaking, and its height reaches 5m or more. To save lives of residents in these affected areas from the tsunami, a shelter tower is newly designed, and it begins to be constructed by the local governments. A hydraulic experiment is performed to check the stability of the shelter tower at exertion of the tsunami. It is confirmed that if there are no debris, the tower is enough stable because tsunami force is smaller than shear strength of the column connections. On the other hand, if the force is increased by debris, overturning moment becomes much larger than the resistant moment by the tower weight without considering the pullout resistance force of the columns. Presuming of tsunami force which acted on land structures such as the tsunami shelter was proposed by using newly derived tsunami velocity equation and the drag coefficient of the structures.

DOI： 10.2208/prooe.23.99

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The present study examines the soliton fission process of tsunami propagating over reef shallow water coast by hydraulic experiments. The effects of water depth above the reef, tsunami amplitude and period are investigated. In addition to the experiments, two different kinds of numerical models are employed in order to know how accurately the models can reproduce the process of tsunami transformation such as the occurrence of fission, amplitude, number of soliton waves and phase celerity propagating over the reef. It was found that even if the tsunami amplitude and period are the same, the transformation process of first water-level-rising tsunami is different from that of first-falling tsunami and that there are differences between experimental transformations and numerically obtained transformations generally.

DOI： 10.2208/prooe.23.165

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Publisher：Japan Society of Civil Engineers  

A tide-surge-wave coupling model has been developed by employing a nesting scheme to be simultaneously parallelized by MPI. By using this model, effectso flarge tidal variation on storm surges and wave set-up were assessed for the case of simplified bathymetry and the western coastal sea of Korea. The effect of large tidal variation is confirmed to reduce the magnitudes of the storm surges and set-ups. Especiallyt, he effect is a predominant factor for the occurrence of severe disaster due to typhoons in the sea where the large tidal variation takes place such as the western coastal sea of Korea.

DOI： 10.2208/proce1989.54.276

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

The Indian Ocean Tsunami on 26 December 2004 affected Sri Lanka, which is located 1,700 km from the epicenter. A field investigation was conducted along the southwest coast of Sri Lanka to measure tsunami trace heights, investigate the damage, and obtain correct information on the tsunami. The results of the field survey showed that the tsunami arrived on the Southwest coasts two and a half hours or more after the earthquake. The average tsunami height was 5 m along the southwest coast and tsunami trace heights of 10 in were found call v. The tsunami destroyed a number of wooden and brick houses, damaged port and harbor facilities and coastal railways, washed away many vessels, and scoured the foundations of coastal structures. The port and harbor facilities such as the breakwaters, and rigid coastal houses continuing along the coast reduced the tsunami and lessened the damage that it caused.

DOI： 10.1142/S0578563406001362

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DOI： 10.20965/jdr.2006.p0148

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Language：Japanese   Publisher：日本沿岸域学会  

CiNii Books

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

本研究は, コスト削減の観点から, 護岸被覆材 (特に消波ブロック) のライフサイクルコスト (以下, LCCと略す) を最小化する最適設計手法を提案するものである. 本手法では, LCCとして初期建設費用および耐用年数間の補修費用のみを対象とし, 補修費用については高橋ら (1998) が提案した被災度の経験式を用いて算出している. 本手法による検討結果では, 要修復基準である要補修被災度を大きくとると最適重量は軽くなった. また, 水深が浅い場合には, ハドソン公式で求めた重量よりも重いブロックが最適重量となるが, 水深が深い場合には, ハドソン公式で求めた重量とほぼ同程度のものが最適重量となった.

DOI： 10.2208/proce1989.53.856

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

A big difference between the Andaman Sea coast and the coasts in the western countries of the Indian Ocean was found in damage state caused by the Indian Ocean Tsunami. It is thought that geographical features of the coastal cross-shore section affect the characteristics of the tsunami deformation and the damage situation of the coastal structures. In this paper, the model experiments were conducted to clarify the difference of deformation, breaking, runup or pressure of tsunami by the characteristic of the coastal cross section. The wave steepness and water depth on the reef are closely related to generation and development of dispersive solitons, and it is clarified that the impulsive breaking wave force takes place at the breaking of individual soliton. Tanimoto's empirical formula can be applied to estimate the wave force of tsunami on coastal structures when the dispersive solitons almost disappear due to these breaking or no dispersive solitons occur.

DOI： 10.2208/prooe.22.529

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The present design procedures for the breakwater with footing ignore a wave pressure acting on the footing under the assumption that the compressive force on the upper face of the footing can be cancelled by the uplift force on the bottom face of the footing. This assumption is acceptable, but the experiments have confirmed that the compressive force becomes much lager for the case of long footing than the uplift force and works to stabilize the breakwater. We have proposed two empirical formulas for the distributions of uplift and compressive pressures. However, the validity of the formulas was not confirmed for random wave experiments. The present paper describes the confirmation of their validity thorough the experiments in random wave and numerical simulations. The empirical formulas are slightly improved.

DOI： 10.2208/prooe.22.319

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

3種類の気象データ (NARR, GFS, FNL), 3種類の風から波へのエネルギー伝達モデル (Komenら, Janssen, Lalbeharryら) および計算対象周波数領域を2種類としてハリケーン・カトリーナによる高波追算を行い, 観測結果と比較して, 1) 空間・時間分解能がよいNARRを用いても推算結果は観測結果をうまく再現できない, 2) GFSとFNLは同程度の結果が得られる, 3) エネルギー伝達モデルはKomenらが全般的に良く, Janssenでは観測結果に比べて小さくなる, 4) 最も大きな有義波高が観測された地点で再現性が良かったのは, Lalbeharryらのモデルを用いた場合であることを示した.

DOI： 10.2208/proce1989.53.421

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Hurricane Katrinaによる高潮, 高波被害の実態を調査し, 日本の高潮, 高波被害対策に資する教訓を得た. 被災の全体的な特徴としては広域性 (延長300km以上に渡る被災, 州を越えての長距離避難), 甚大性 (死者1, 300人余り, 膨大な数の避難者, 都市機能の停止), 長期性 (今も避難を余儀なくされている多数の人々, 都市の衰退への動き) が挙げられる. 自治体ごとに被災時の対応が異なったため, 住民が避難していなかった所と前夜に住民が避難していた所では被害の出現, 復興のプロセスも異なっていた. このような被害の多様性を分析した上で, 防災計画を地域の多様性を前提にして練り上げていく必要がある.

DOI： 10.2208/proce1989.53.401

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

地震発生時の津波を推定する際, 断層情報をいち早く知ることによって津波予測精度の向上を図るために, 観測データを用いたリアルタイム津波予測手法を検討した. 津波シミュレーションによって求めた室戸沖および潮岬沖 (想定設置点) のGPS波浪計における津波水位の時系列変動から, ガウス・ザイデル法を用いて逆解析を実施し, 波源域と到達波高の推定を試みた. 大阪湾外の観測波形と逆解析によって求めた到達波高の時系列を比較したところ, 精度の良い結果が得られた. 波源域の推定および大阪湾内の津波高の予測には, 観測時間による影響が大きく, 観測時間が長くなれば, 津波波形の再現精度が上がることがわかった.

DOI： 10.2208/proce1989.53.311

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外洋遠方から進行する台風が, 大陸棚を通過して沿岸域に接近する場合の, 海水密度流の3次元数値解析を行なった. 表層内の水平渦流が鉛直循環流を伴い, その結果, 界面の上昇が生じた. 台風の中心より後方に最高水位が, その後方に水平渦流の中心が位置し, 界面は, 更に後方で上昇した. 界面の上昇位置は, 大陸棚外縁に至るまで台風に追従し, 内部界面の高まりは, 大陸棚外縁から外洋までの広水域に及んだ. 内部波は, 大陸棚外縁近傍で, 初期上層水深が深いほど大きな最大波高を示した後, 透過波・反射波成分と, 大陸棚外縁に沿って進む成分とに分離した. この最大波高に対する大陸棚上の内部波波高の比は, 大陸棚上の下層水深が深いほど高くなった.

DOI： 10.2208/proce1989.53.361

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

2003年9月に韓国南部を縦断した台風14号によって慶南道馬山市では, 高潮による未曾有の災害が発生し, 地下施設への浸水により十数名の死者が出た. 本研究では, 地下施設内での海水の流動を3次元流体解析モデルで解析し, 地下室の浸水に要する時間, 流入する海水の流速等を明らかにし, 被災に至ったメカニズムを解明した. 次に, 今後の浸水対策として臨港部に高さ1mの防潮壁を建設する方法ならびに被害を受けた地下施設の入り口に高さ50cmの止水壁を設ける手法を提案し, その効果を数値計算で検討した. 計算の結果, 防潮壁や止水壁により地下施設への浸水開始時刻が遅くなり, 地下室内の浸水深も大幅に低下されることが明らかになった.

DOI： 10.2208/proce1989.52.206

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Language：English   Publishing type：Research paper (international conference proceedings)  

A new observation system for wave overtopping at sea walls (On-site Wave Overtopping Sensor) has been developed. The system is composed of several step type wave gages installed at the edge of sea wall. The variation of water surface elevation above the crown level of sea wall is obtained during a storm employing the system. A field test using the system was carried out in the Port and Airport research Institute facing to the mouth of Tokyo bay when a typhoon passed in the bay. The measured data was applied to study on the time-dependent variation of wave overtopping rate at the observation point. The analyzed data demonstrated the applicability in field. The prototype system was installed in the Shimizu Port and it worked without any trouble for the target hours.

DOI： 10.1142/9789812701916-0350

Scopus

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

実海域における海底地盤表層の動態については, 未だ不明な点が多い. 著者らは, 水深15mの観測サイトにおいて, 2003年と2004年に防波堤基礎地盤内における間隙水圧の応答観測を実施してきたが, 構造物下地盤において鉛直方向の観測深度の違いによって間隙水圧に位相差が生じるといったような原因の不明な特性を確認した. 本研究は, VOF-FEM法による間隙水圧の数値計算によって, 観測結果で得られた特性を明らかにし, 高波浪時の地盤内間隙水圧の波浪応答を解明するものである.

DOI： 10.2208/proce1989.52.851

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

本研究では, 防波堤直下の基礎地盤における水圧と間隙水圧の系統的な現地観測を実施し, そのデータに基づき, 高波浪が作用したときの海底砂質地盤の応答を明らかにすることを目的としている. 観測は, 2003年から2004年にかけて3つの台風 (T0310, T0416, T0423) を対象とし, 高知港の東第一防波堤サイトにおいて実施した. 現地観測の結果から, 残留間隙水圧の長周期変動成分は, 来襲波浪の波群特性と密接な関係があることがわかった. また, 液状化については, 構造物による上載圧の増加を考慮すると, 法先自由地盤を除いて, 発生する可能性は極めて低いという結論に達した.

DOI： 10.2208/proce1989.52.846

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

There is a little time to react until the tsunami arrival in each port in Osaka Bay in case of Nankai Earthquake occurrence. Therefore, it is possible to take precautions against the tsunami if appropriate tsunami information can be obtained. In this study, the real-time tsunami forecast system which can complement the forecast of the Meteorological Agency is examined. The real-time tsunami forecast method which is proposed in this research forecasts the tsunami that reaches in Osaka Bay 1 to 1.5 hours later by using the observed data outside the bay. The Shirahama Observation Tower in Tanabe Bay, Wakayama is considered as one of the offshore tsunami observation facilities. As a result of the examination, the accuracy of this method using the observed data was well and usefulness was confirmed.

DOI： 10.2208/prooe.21.145

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Language：Japanese   Publisher：土木学会  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

台風0423号によって日本各地で起こった高波災害のうち, 和歌山県すさみ町周参見漁港西防波堤の被災を調査した. 沖波波浪の追算, 浅海波浪の推算計算による防波堤前面での波高分布, 防波堤の滑動量を解析した. Kim・Takayama (2004) の滑動量算定手法を用いて滑動量を求め, 実測値と比較してその有用性を検討した. ケーソンの傾き (tilting) によってケーソン後趾に生じる滑動抵抗力を考慮することにより, 周参見漁港で生じた防波堤の被災状況を再現し, 本解析手法の有用性を確認した.

DOI： 10.2208/proce1989.52.791

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

台風0314号によって葦山市の西側に位置する馬山市においては, 高潮による未曾有の災害が発生し, 地下施設への浸水により十数名の死者が出た.本研究では, 浸水被害の規模や地下への浸水状況を調べるために現地に赴き, 最高水位の痕跡値を調査し, 街路の地盤高や代表的な地下施設の寸法などを測量した.流入口が広い地下駐車場よりも下層に店舗が設定されるという, 建築構造上の欠陥が被害を大きくした一因であることが明らかになった.MARS法を用いた3次元流体解析モデルによって, 地下施設を含む浸水解析を実施した.解析結果を痕跡値の測量結果と比較したところ, 浸水状況をほぼ正確に再現することができた.

DOI： 10.2208/proce1989.51.1366

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Knowledge on the flood risk due to tsunami and storm surge is slight in the persons living in coastal urban areas. The information of the size of anticipated damage and influence to evacuation routes is not enough for them to minimize the hazard risk by inundation.<BR>In this research, the inundation in the coastal urban area caused by tsunami attack is analytically estimated, and the display system on the website was developed. The site is capable for sending the understandable information on the risk through the internet.<BR>The inundation calculation was conducted according to the characteristics of the land use of coastal area, and the relational expression was derived between the distance from the seawalls line and the arrival time, the maximum depth, the maximum celerity. It is possible to display the inundation risk of the maximum design tsunami on the target coastal regions.

DOI： 10.2208/prooe.20.27

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

遊歩道付き護岸等の親水性施設での安全管理に役立てることを目的として, 護岸での越波や越流をリアルタイムで計測するためにオンサイト越波計が開発された.オンサイト越波計は, ステップ式波高計を改良して, 5cm間隔で電極を張り付けた長さ1mの測定桿を護岸上に設置したものである.オンサイト越波計の現地適用性を調べるために, 神奈川県久里浜湾の護岸で現地観測が実施された.2002年10月1日の台風0221号来襲時の観測において, 越流高から計算された10分間平均越波流量は, 同時に観測された集水升による越波流量に一致し, オンサイト越波計の現地適用性が検証された.

DOI： 10.2208/proce1989.50.626

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

都市臨海部は高度に開発されており地下施設が存在する場合もあるため, 構造物による影響を粗度として取り扱うだけでは不充分であり, 3次元的な浸水リスクの解析が必要と考えられる.本研究では, MARS法を応用した高精度な浸水リスク解析手法を提案し, 臨海都市部を対象にその有用性を検討した.解析の結果, 地上と地下の浸水状況を同時に再現できることを確認した.また, 浸水状況の解析結果をCGによって人の視点で可視化することもでき, 危険度の理解が容易になる.さらに, 地図データベースと土地利用状況情報を入手できれば, 各都市の臨海部において, 家のサイズまで認識可能な精度での浸水リスク予測が可能である.

DOI： 10.2208/proce1989.50.301

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

都市臨海部においては, 土地利用の高度化や地下空間の利用拡大といった高度利用が促進される反面, 伊勢湾台風を契機に整備されてきた海岸保全施設の老朽化, 異常潮位や温暖化による海面上昇など外力条件が厳しくなり, 大きなリスクが生じつつある. 沿岸津波についてはその危険度が広く認知されているのに対し, 津波による臨海部市街地の氾濫災害については, あまり想定されていない.本研究では, 建物と地下施設が混在した首都圏の複合市街地を対象に, 氾濫水の挙動特性や地下での浸水深, 流速などを測定し, 津波による浸水危険度の高さを模型実験で調べた.その結果, 地下空間の危険度は特に高く, 避難が非常に困難な状態になることがわかった.

DOI： 10.2208/proce1989.50.271

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Publisher：Japan Society of Civil Engineers  

The purpose of this study is to improve the effect of gentle slope-type seawall on prevention of wave overtopping. With this in view, the experiments on irregular wave overtopping are carried out for a gentle slope and roughened seawall. In these experiments, artificial wave furrows are used as a roughness. Consequently, the effective arrangement and shape of artificial wave furrows are clarified to prevent wave overtopping. In addition, the Weibull distribution can be applied to approximately the frequency distribution of wave overtopping rate over a gentle slope and roughened seawall.

DOI： 10.2208/prooe.14.393

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土木学会津波研究小委員会編

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