DOI： 10.2208/jscejoe.75.I_61

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Publishing type：Research paper (scientific journal)  

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

Scopus

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

<p> In order to evaluate coastal geomorphic changes and potential impacts of tsunami-induced sediment transport in Kochi Prefecture caused by the Nankai Trough megathrust earthquake, numerical simulations of sediment transport over a wide area of Tosa Bay have been performed. The regional features of potential impact was provided. The tsunami-induced sediment transport can cause not only large-scale erosion and sedimentation around the coastal zone but also increase in tsunami hazards. Note that the influences depend significantly on uncertainties in bed materials, i.e. grain sizes and distributions of erodible/noerodible surfaces. The uncertainties in the simulations will be improved through acquisition of detailed sedimentary data. Further discussions considering the regional characteristics of tsunami-induced sediment transport will provide the resilient countermeasures to tsunami disaster.</p>

DOI： 10.2208/kaigan.75.I_685

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DOI： 10.2208/kaigan.74.I_1369

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, factors causing the underestimation of morphological changes due to tsunami-induced sediment transport in Kesennuma Bay with narrows during the Great East Japan Earthquake and Tsunami have been numerically investigaed. Based on the estimation, the saturated concentration of suspention model was improved. It was found out that strong unsdeady flows occerred at narrows. The numerical results from conventional saturated concentration model implied that at the narrows, suspension concentration and sediment supply from the bottom to the suspension were limited by high concentration in suspension, leading to underestimation of morphological change, i.e., erosion and deposition. By considering effects of strong unsteady flows on concentration of suspention, a new form of saturated concentration model based on log-wake law and Kármán constant theory has been proposed. Numerical results of the erosion and deposition in Kesennuma Bay were improved. It is expected that accuracy of evaluation about not only morphological changes but also inundation area and damages are improved.

DOI： 10.2208/kaigan.74.I_325

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Other Link： http://id.ndl.go.jp/bib/029324989

DOI： 10.2208/kaigan.74.I_541

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Publishing type：Research paper (scientific journal)  

The grain size distribution of a tsunami deposit may have a correlation with the tsunami inundation process, and further with the tsunami source characteristics. We test this hypothesis using thickness and grain size distribution data of the 2011 Tohoku tsunami deposit in Numanohama coast, Iwate Prefecture, Japan. Here, we build and validate a tsunami sediment transport model that can simulate deposit thickness and grain size distribution. Our numerical model has three layers: parent (bed), deposit (bed), and suspended load layers. The two bed-layers contain information about the grain size distribution. This numerical model can handle a wide range of grain sizes from 0.063 (4ϕ) to 5.657 mm (−2.5ϕ). The grain size distributions at 12 sample points along a 900 m transect from the beach, through a marsh, and up to the inundation limit, are used to validate the tsunami sediment transport model. We adopt a reference tsunami source model that can well reproduce the observed tsunami run-up heights ranging from 16 to 35 m along the steep valley during the 2011 tsunami. The simulated sand thickness distribution along the transect is consistent with the observed thickness ranging from 3 to 23 cm. The computed net erosion and deposition suggest that most of the sand deposit was originated from the near shore. The shapes of the simulated grain size distributions represented by their sorting, skewness, kurtosis, and mean at most of the sample sites are similar to the observations. The differences between the observed and simulated peak of grain size distributions are less than 1ϕ. To evaluate the sensitivity to the tsunami source model, we test five tsunami scenarios which are modified from the reference source model. While the tsunami scenario with 120% of the reference amplitude can also reproduce the thickness and grain size distribution, the scenarios with amplitudes smaller than 80% of the reference or with wave periods shorter than 50% of the reference source model underestimate the thickness and cannot reproduce the grain size distributions. Our simulation results suggest that it is possible to estimate tsunami wave amplitude and wave period from sediment deposit thickness and grain size distribution data.

DOI： 10.1016/j.margeo.2018.08.003

Scopus

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Publishing type：Research paper (scientific journal)  

© 2018 by the authors. The tsunami generated by the 2011 Tohoku-Oki earthquake was the first time that the velocity fields of a tsunami were measured by using high-frequency oceanographic radar (HF radar) and since then, the development of HF radar systems for tsunami detection has progressed. Here, a real-time tsunami detection method was developed, based on virtual tsunami observation experiments proposed by Fuji et al. In the experiments, we used actual signals received in February 2014 by the Nagano Japan Radio Co., Ltd. radar system installed on the Mihama coast and simulated tsunami velocities induced by the Nankai Trough earthquake. The tsunami was detected based on the temporal change in the cross-correlation of radial velocities between two observation points. Performance of the method was statistically evaluated referring to Fuji and Hinata. Statistical analysis of the detection probability was performed using 590 scenarios. The maximum detection probability was 15% at 4 min after tsunami occurrence and increased to 80% at 7 min, which corresponds to 9 min before tsunami arrival at the coast. The 80% detection probability line located 3 km behind the tsunami wavefront proceeded to the coast as the tsunami propagated to the coast. To obtain a comprehensive understanding of the tsunami detection probability of the radar system, virtual tsunami observation experiments are required for other seasons in 2014, when the sea surface state was different from that in February, and for other earthquakes.

DOI： 10.3390/rs10071126

Scopus

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In the 2011 Tohoku earthquake tsunami disaster, the oceanographic radars installed at the coastal area of Japan and USA observed the tsunami, which proved the possibility for tsunami observation by using oceanographic radar. After the Tohoku tsunami, studies by using oceanographic radar were reported, but the research topics were mainly on tsunami observation and detection. Quantitative evaluations such as the estimation of wave peak is important in order that oceanographic radar contributes to tsunami disaster prevention and mitigation. In this study, the method to estimate a wave peak of tsunami by using a single oceanographic radar was examined and applied for a tsunami scenario in the Nankai Trough. The tsunami numerical modeling for the tsunami source of <i>M</i>w9.1 and 8.6 in the Nankai Trough was carried out and gave radial velocity distributions to be observed by oceanographic radar. The wave peak was estimated by using the radial velocity distribution and was compared with the wave peak calculated by the outputted water distribution. As a result, the location of the wave peak is estimated well. And the water level of the wave peak is estimated with an error range of -20% to 10%.

DOI： 10.2208/kaigan.74.I_511

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;We attempted to observe the 2015 Illapel Earthquake Tsunami in Japan by using the oceanographic radar, however we could not detect it. Hence, we carried out numerical modeling of the tsunami and showed that the tsunami velocity was smaller than the observable velocity of the radar. On the other hand, a numerical experiment of the 1960 Chile Earthquake Tsunamis indicated that the radar could have detected it. Further, we conducted a virtual tsunami experiment including background noise and observation flow. The experiment result showed that the tsunami detection distance was 25.5 km when cross-correlation calculating period and distance were 3 hours and 3 km.

DOI： 10.2208/kaigan.73.I_433

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;Because use of vehicles during evacuation caused serious damage in Tohoku earthquake, it was recognized that it was necessary to think about ways to evacuate safely even if the residents use cars. In this research, we propose a numerical model considering the interaction between pedestrians and vehicles in evacuation. By observing the behavior of the pedestrians and vehicle in the field experiment, getting the basic data of simulation and verifying the simulation model were carried out. Then, we adapted the model into Tokushima City where is predicted severe damage by the Nankai Trough Earthquake Tsunami. Twe examine the influence of using vehicles in evacuation, 4 cases of ratio of vehicles to pedestrians were caluculated. As a result, when the amount of automobiles is over 25%, the completed evacuation rate was decreasing. Moreover, some congestion places due to mixing pedestrians and vehicles was found.

DOI： 10.2208/kaigan.73.I_349

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;An integrated tsunami model consisting of models for simulating tsunami inundation, drifting objects and sediment transport, was newly developed to evaluate the effects of these multiple phenomena. A scenario of complex tsunami damage enlargement in a bay with bottleneck was revealed. The tsunami hazards in Kesennuma City, especially at the inner part of the bay such as Shishiori area, were enlarged by erosion in the bottleneck of the bay. The bathymetric change increased the drift distance of the drifting vessels. In addition, through the tsunami fragility functions based on dataset of actual damaged building and numerical results, it was evaluated that the 200 - 1,800 wooden buildings were washed away owing to sediment transport. Furthermore, it is found that the estimation accuracy of damage scale by the conventional fragility functions was suitable, although the estimated building damage near the sea and inland was under and overestimated, respectively.

DOI： 10.2208/kaigan.73.I_355

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;On the tsunami disaster mitigation, it is important to take measure against buildings damage and disaster debris in addition to inundation. In this study, a tsunami numerical model considering building collapse and disaster debris model was applied for Owase City which is assumed to receive great damage by the Nankai Trough tsunami. And, the effect of tsunami damage evaluation which focused on the difference in the type of buildings structure in the coastal area was also studied. As a result, the proposed model predicts accurate inundation compared with the conventional model. The proposal model was able to estimate the damage of buildings and disaster debris, and also made it possible to estimate the damage by various tsunami scenarios quantitatively and concretely. The proposed model seems to be useful for the tsunami disaster prevention plan such as the damage estimation and mitigation.

DOI： 10.2208/kaigan.73.I_403

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;The underestimation of 2011 Tohoku tsunami caused serious damage. Reconsideration for tsunami estimation needs knowledge of paleotsunamis. The historical records of giant tsunamis are limited, because they had occurred infequently. Tsunami deposits may include many of tsunami records and are expected to analyze paleotsunamis. However, present research on tsunami deposits are not able to estimate the tsunami source and its magnitude. This study investigated the formation mechanism of tsunami deposit by hydraulic experiment. The effect of sand grains and bore wave were examined. As the result, bore wave amplitude and multiple waves were related with the amount of deposit and distance of run-up. The mixed ratio of three grain sizes in sand bed section corresponded with the composition ratio of the sand deposit near the shoreline. Further, cutoff wall and shorter wave period increased tsunami deposits.

DOI： 10.2208/kaigan.73.I_367

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In this study, it was found that through the numerical simulations of sediment transport in case of the 2011 Great East Japan Earthquake and Tsunami in Rikuzentakata City, the water level of the entire city area increased roughly by 1 m through the damage of the seawalls and the water level on the eastern and inner parts also increased remarkably because of the sand dune and riverbed erosion. Moreover, such damages caused the return flow near the coast line to amplify by about twice. On the other hand, using offshore tsunami waveforms, this study proposed a quantitative estimation method of the magnitude of return flow, <i>M</i>_RF. Estimation of the <i>M</i>_RF was then performed and applied for the Nankai Trough Great Earthquake and Tsunami. The return flow around Tosashimizu and Tokai Area would be equal to or greater than those on Rikuzentakata City or Onagawa Town during the 2011 tsunami. Based on lessons from the 2011 tsunami, since <i>M</i>_RF was larger than 0.0003, the typical value in Sanriku Coast, <i>M</i>_RF will be important reference for consideration among other countermeasures against future tsunamis.

DOI： 10.2208/kaigan.73.I_361

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In the present study, a hydraulic experiment with moving bed was carried out in order to investigate the influence of particle size of sand, slope of run-up areas, and tsunami conditions, to distributions of sand deposited on land slopes by tsunamis. Then, the following matters were examined by using experimental data; the relationship between the run-up distance and deposit formation distance, the relationship of the distribution of the sediment and the incident wave, the difference in the distribution of the deposit due to the difference in particle size of the source sand, the distribution of the deposit by uniform sand and mixed sand. From experiment results, it is shown that the ratio of deposit formation distance and tsunami run-up distance is influenced 0.67 to 1.0 by particle size of sand. This ratio is also changed by slope condition and tsunami wave settings. And the mass distribution of deposit is changed by the particle size of source sand. When utilizing tsunami deposits, it is necessary to consider not only layer thickness but also particle size.

DOI： 10.2208/jscejseee.73.I_634

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In the 2011 Tohoku earthquake tsunami disaster, the delay of understanding damage situation increased the human damage. To solve this problem, it is important to search the severe damaged areas. The tsunami numerical modeling is useful to estimate damages and the accuracy of simulation depends on the tsunami source.<br>&nbsp;In this study, we proposed the new method to estimate the characterized tsunami source model by using the limited observed data of GPS buoys. The model consists of Large slip zone (LSZ), Super large slip zone (SLSZ) and background rupture zone (BZ) as the Cabinet Office, Government of Japan^{10), 11)} reported after the Tohoku tsunami.<br>&nbsp;At the beginning of this method, the rectangular fault model is assumed based on the seismic magnitude and hypocenter reported right after an earthquake. By using the fault model, tsunami propagation is simulated numerically, and the fault model is improved after comparing the computed data with the observed data repeatedly. In the comparison, correlation coefficient and regression coefficient are used as indexes. They are calculated with the observed and the computed tsunami wave profiles. This repetition is conducted to get the two coefficients close to 1.0, which makes the precise of the fault model higher. The proposed method by using GPS buoy was applied for a tsunami scenario in the Nankai Trough. As a result, the final estimated Moment magnitude (<i>M</i>w) and the location of LSZ and SLSZ are estimated well.

DOI： 10.2208/kaigan.73.I_307

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

A numerical sediment transport model (STM) was used to investigate coastal geomorphic changes that resulted from the 2011 Tohoku earthquake tsunami in Rikuzentakata City and Hirota Bay on the southern Sanriku Coast of Japan. The simulation was verified using observed inundation processes and heights, measured topographic changes and sediment deposition. Aerial video footage recorded by the Iwate Prefectural Police was also used. The results show that the numerical model was able to predict the spatial distribution and volume of erosion and deposition in Hirota Bay, as well as sediment transport processes. The effects of sediment transport on tsunami inundation were also investigated. Numerical results revealed that the majority of the sand dunes were eroded by the first wave, especially during the strong return flow of the receding wave. Large flows and sand dune erosions can occur elsewhere if tsunamis inundate a plain with a limited shore-normal width. These events could cause large-scale morphological changes comparable to those that occurred in Rikuzentakata City.

DOI： 10.1142/S0578563416400155

Web of Science

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;Hydraulic experiments and numerical simulations were carried out in order to analyze the influence of the planar shape of coastal sea area on sediment transport and bottom topography change due to tsunami. High velocity flow occurred due to the passage of tsunami through the abrupt expansion and a circulation flows took place in the rear area of the structure. The circulation flows generated behind the structure were found to be the same scale regardless of the length of the rear area. Therefore, deposit area with the same position and scale was formed even if the scale of the rear area was different. The numerical results also revealed that the introduction of the diffussion terms into the equations of fluid motion and suspended sediment are necessary to reproduce flow structure and topography change.

DOI： 10.2208/kaigan.72.I_607

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Language：Japanese  

DOI： 10.2208/kaigan.72.I_343

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;Coastal lakes are considered as suitable sites to keep tsunami deposits in good condition. For more effective use of these tsunami deposits for estimation of magnitude of historical tsunami events, it is necessary to understand the process of morphological changes in coastal lakes induced by tsunamis and also quantitative relationship between overflow condition of tsunami and amount of morphological changes. In this study, morphological changes in a coastal lake model were measured by imaging techniques and compared with the overflow condition of dambreak flow flooding into the model.<br>&nbsp;From the side view recorded by a high speed camera, development of local scour around the upstream end of the lake was extracted, and it is found that increase speed of the scour depth is almost same for different wave conditions and the final scour depth can be determined by the time until water surface breaking around the scour which seems to be induced by decrease of inertia of the overflow against pressure gradient around the downstream slope of the eroded ground.<br>&nbsp;Instead of the time until the surface breaking, duration of the overflow can explain the final scour depth at the seaward end of the lake, while the width of the eroded area depends on the overflow depth. Thicker deposited layer was formed in tha cases with longer duration of overflow where more sand was supplied from the eroded area to the inner side of the lake. Average position of the deposition is further from the seaward end of the lake with larger overflow depth which induce high velocity in wider area.

DOI： 10.2208/kaigan.72.I_391

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;A lot of debris by tsunami, such as cars, ships and collapsed buildings were generated in the 2011 off the Pacific coast of Tohoku Earthquake. It is useful for rescue and recovery after tsunami disaster to predict the amount and final position of disaster debris. The transport form of disaster debris varied such as drifting, rolling and sliding. These transport form needs to be considered comprehensively in tsunami simulation. In this study, the proposed numerical model considering disaster debris was compared with experiment for verification. And, the numerical model was applied for Kesennuma city where serious damage occurred by the 2011 Tohoku tsunami. As a result, the proposed model showed that it is necessary to take the disaster debris into account in order to predict tsunami inundation accurately.

DOI： 10.2208/kaigan.72.I_439

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Language：English   Publisher：The Visualization Society of Japan  

Numerical models for tsunami phenomena have been improved to estimate various tsunami damages. However, they are not sufficiently utilized for tsunami disaster reduction measures, because the computed results are getting more complicated. It is necessary to visualize the simulated tsunami disaster scenarios. In this research, a method is developed to visualize the complicated tsunami risks by using Marker Vision based Augmented Reality. The multiple markers are connected with the computed tsunami animation, a pause function of animation, and a detailed urban structure model which consists of the ground, the sea, roads and buildings. Their respective computer graphics corresponding the markers are projected in the real world by using a camera-embedded eyeglass. And a tsunami numerical modeling was conducted to make the tsunami animation. It assumed a huge earthquake of magnitude 9.1 in the Nankai Trough and simulated its tsunami inundating in Kobe City. The proposed method can be applied for many measures such as tsunami hazard map and Disaster Imagination Game.

DOI： 10.3154/tvsj.36.32

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Language：Japanese   Publisher：海洋出版  

CiNii Books

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

A numerical modeling of sediment transport was performed to investigate coastal geomorphic change due to the 2011 Tohoku Earthquake tsunami in Rikuzentakata City. The simulation was verified for observed inundation process and height, and measured topographic change and sediment deposition. The role of sediment transport on the modeling of tsunami inundation was also investigated.The numerical results revealed that the most of the sand dune was flushed out by the first wave, especially during the strong return flow. Such strong flow and total erosion of sand dune could also occur elsewhere, in case when a tsunami inundate a plain with moderate distance by shore-normal direction to the coastline.

DOI： 10.2208/kaigan.71.I_499

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017139159?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Tsunami flow and structures such as buildings interact with each other. Influence of buildings on numerical simulation of tsunami inundation was studied in this paper. The three kind of methods to consider the effect of building on tsunami flow were adapted in Kesennuma city where serious damage occurred by the 2011 Tohoku tsunami. By comparison of computed inundation with measured, the wave force threshold that causes building collapse and washed-away was determined. A simulation considering the collapse of the building by using the threshold showed the influence of buildings washed-away is necessary to simulate accurate tsunami inundation.

DOI： 10.2208/kaigan.71.I_163

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017142883?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The tsunami deposit is tend to be preservable in a coastal lake. In this research, the hydraulic experiment on tsunami rushing into a coastal lake was carried out with fixed bed condition.<br> The experimental results showed that hydraulic jump occurred according to inundated flow flooding into the lake, and the state of flow changes complicatedly with the lapsed time. The changing flow state was depending on a lake scale. Furthermore, the water level and the flow velocity on the bottom became maximum near the dune back, and the maximum flow velocity was decreased when lake depth deeper. The results could give important knowledge for the depositional process of tsunami deposit in a coastal lake.

DOI： 10.2208/kaigan.71.I_229

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017141114?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Understanding of characteristics of morphology change induced by tsunamis is necessary for estimation of magnitudes of historical tsunamis. In this study, morphology change in coastal lakes caused by tsunami intrusion is discussed through a hydraulic model experiment. A horizontal open channel with 1/100 model of a coastal lake was used for a movable bed experiment. Temporal variation of bed shapes under dam-break flow is extracted from video images recorded from the side by a high-speed camera. And three dimensional bed shapes before and after the experiment are measured by an image measurement technique to get horizontal distributions of bed level changes. In this technique, object surfaces under color dot illumination from a PC projector are recorded by a digital camera, and three-dimensional coordinates of the color dots reflected on the surfaces are determined with geometrical relationship between the camera and the projector.<br> Local scour was developed around seaward end of the lake model by the dam-break flow in all cases. While the erosion was limited in the area near the seaward end of the lake, deposition was observed in wider area behind the scour. With higher wave condition, the scour behind the mound was deeper and wider. While the deposition area behind the scour was also wider with the higher waves, maximum thickness of the deposit layer was smaller. It is found that a rate of increase of the scour depth is almost same among the cases with different wave conditions and hense duration of higher velocity is more important factor to increase the scour depth.

DOI： 10.2208/kaigan.71.I_235

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017141084?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

A large-scale topographical variation occurred in Kitakami river mouth due to the 2011 Tohoku-oki earthquake tsunami. Land use is often developed in river mouth areas in Japan. As a variation by tsunami can be a factor of impediment to post-disaster recovery and reconstruction, it is important to clarify the process of a topographical change by tsunami in river mouth area.<br> In this research, numerical simulations for tsunami sediment transport were carried out in Kitakami river mouth and the numerical results explain that 1) the erosion of the sandbar near the river mouth was proceeded by tsunami run up, 2) sediment was deposited in rice field of upper stream, and 3) sediment transport close to offing of the river mouth was caused by tsunami back wash.

DOI： 10.2208/kaigan.71.I_247

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017141015?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study examines the possibility of detecting the first wave of a tsunami by oceanographic radar based on a virtual tsunami observation experiment. Radial velocities obtained by tsunami simulation are converted into modulating signals and superimposed on signals measured by oceanographic radar installed on the Mihama coast. Then the radial velocities are calculated from the combined signals which are to be measured by oceanographic radar. We call this procedure 'virtual tsunami experiment', and use it to investigate the possibility of tsunami detection using cross-correlation between two observation points in a radial direction. When the cross-correlation increases significantly and in a correlated manner with the passage of the first tsunami wave, we judge that the oceanographic radar has detected the tsunami at the points where the correlation is calculated. We found that the location of the furthest-offshore points where the first wave was detected by the radar depends on the distance between the two observation points. The dependence of the distance of tsunami detection on the distance between the two points is also discussed.

DOI： 10.2208/kaigan.71.I_337

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Other Link： https://jlc.jst.go.jp/DN/JLC/20017141954?from=CiNii

Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In the 2011 Tohoku earthquake tsunami disaster, the underestimation of tsunami warning and the delay of understanding damages state increased the human damage. To improve these problems, it is important to upgrade tsunami monitoring. In this study, the tsunami observation by oceanographic radar was examined. The model for analyzing multiple tsunami scenarios was applied to the earthquake of <i>M</i>w 9.1, 8.6 and 8.4 in the Nankai Trough, and the tsunami sources of 39, 63 and 75 cases were assumed. The numerical modeling using the tsunami sources gave velocity distributions to be observed by oceanographic radar. They showed that the oceanographic radar can observe LSZ and SLSZ in the tsunami source, and tsunami propagation in closed sea or near cape. Finally, the 7 observation sites for long-range oceanographic radar and the 15 sites for the mid-range oceanographic radar were proposed.

DOI： 10.2208/kaigan.71.I_343

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In the 2011 Tohoku earthquake tsunami disaster, the actual tsunami heights greatly exceeded the estimated heights and this underestimation resulted in serious damage in Japan. After the Tohoku tsunami, the Cabinet Office of Japan^4),5) reported a large slip zone (LSZ) and a super large slip zone (SLSZ) related to asperity and their assumed tsunami fault models. This led to organizations considering a new assumption in fault models. However, the resulting shapes or locations of LSZ and SLSZ differed from those reported by the Cabinet Office and organizations, and a standard method has not yet been decided. Seto and Takahashi¹⁾ proposed a model for analyzing multiple tsunami scenarios that considers the uncertainties in LSZ and SLSZ. However, that model did not allow considering multiple LSZ and SLSZ, uncertainty in the hypocenter, or uncertainty in the seismic magnitude. In the present study, a general model that considers all of the above uncertainties is proposed. The proposed model is applied to the Nankai Trough to assume multiple tsunami scenarios, and the detailed procedures for using the model are clarified. As an application to tsunami disaster mitigation by using multiple tsunami scenarios, the relationship between the predominant period and the tsunami source is examined. The predominant period is an important factor for tsunami disaster mitigation because it relates to both whether a tsunami warning should be cancelled and how the tsunami height will be amplified inside a port.

DOI： 10.2208/jscejoe.71.I_545

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

As a model to estimate sediment transport and topography change by tsunamis, Takahashi et al. (1999) proposed a movable bed model theoretically and experimentally. In this paper, the model was applied to Kesennuma bay when the 2011 Tohoku Tsunami arrived. It was able to simulate erosion around the narrow area and deposition in the inner part of the bay, however, whole profile was not enough reproduced and deformation volume was underestimated. To improve an accuracy of the model, parameter study was carried out and three dominant factors were found. They are non-dimensional shear stress, coefficients of sediment transport equations, and saturated suspended sand concentration. A model improving the factors is proposed and the model was made remarkable progress for the sediment transport distribution from the entrance to the narrow area of Kesennuma bay.

DOI： 10.2208/kaigan.70.I_491

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/10041329732?from=CiNii

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

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In the 2011 Tohoku Earthquake Tsunami Disaster, the actual tsunami heights had exceeded the estimated heights extremely and the underestimation caused serious damages in Japan. To reduce such a risk, multi tsunami scenarios were examined especially considering Large Slip Zone (LSZ) and Super Large Slip Zone (SLSZ) suggested by the Cabinet Office, Government of Japan. And a recipe of predicting the scenarios is proposed in this paper. The recipe consists of areas, shapes, places and dislocations of LSZ and SLSZ, and the initial crack location. The recipe was applied for the Nankai Trough to predict multi scenario of future large tsunamis and its detailed procedure was shown. Further, the multi tsunami scenarios upgraded the model to avoid the underestimation of tsunami warning by using GPS-mounted Buoys.

DOI： 10.2208/kaigan.70.I_351

CiNii Books

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Other Link： http://hdl.handle.net/10112/8853

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Two oceanographic Radars targeting tsunamis had been installed in Wakayama Prefecture in Japan. To study observation capabilities of the radars on far field and near field tsunamis, numerical experiments were carried out. After starting the operation of the radars, nine earthquakes occurred in the observation area, however, they were too small to be observed by the radars. Parameter study on near field tsunamis showed the radars can observe earthquake of Mw 7 and very shallow Mw 6. As a far field tsunami, the 2012 Haida Gweii Earthquake Tsunami arrived at Japan, however, the radars could not detect it because of very small velocity. Parameter study on far field tsunamis showed the main energy of tsunamis off Canada propagates northward, and Oshika Peninsula is suitable to observe the tsunamis.

DOI： 10.2208/kaigan.70.I_356

CiNii Books

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Other Link： http://hdl.handle.net/10112/8854

Language：English   Publishing type：Part of collection (book)   Publisher：Springer Netherlands  

Erosion and deposition by the 2011 Tohoku-oki tsunami in the coastal areas of the Sendai Plain were numerically investigated using the tsunami sediment transport model (STM). The simulation suggested that much of the sediment deposited on land originated from the beach and dune, whereas the contribution from sea-bottom sediments was quite minor. Erosion observed at the backs of engineering structures such as reinforced concrete (RC) dikes was reproduced well in the simulation. Simulated deposition and erosion inside the nearby coastal forest and farmlands were generally consistent with the observed data. Further investigation of the model parameters and implementation of dynamic change in the roughness coefficient and destruction of the structures are required to simulate detailed local variability of erosion and deposition and of the thin sand layer in the inland areas.

DOI： 10.1007/978-94-007-7269-4_4

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Other Link： https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=377237

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

The 11 March 2011 MW 9.0 Tohoku megathrust earthquake off the Pacific coast of Japan was a salient event in the history of Japan. The resultant huge tsunami (the 2011 Tohoku-oki tsunami) inundated a vast coastal area of northeastern Japan, causing widespread devastation. Twenty days after the tsunami, we analyzed the impact of the tsunami on the sea bottom of the Kesennuma inner bay using side-scan sonar to explore the damage and bathymetric change in the harbor. Herein we present the first direct evidence that the sea bottom sediments of around 10-15m were largely reworked by the tsunami to thickness of a few meters, and that large dunes were formed by the tsunami. Considering that the sea wave influence is as weak as it is inside the inner bay, the potential exists that even meter-thick paleo-tsunami deposits are preserved in shallow sea bottoms with large bedforms. This finding will be a stepping-stone to future geological studies of tsunami effects in shallow sea regions. © 2012 Elsevier B.V.

DOI： 10.1016/j.margeo.2012.11.005

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Language：Japanese   Publisher：海洋出版  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The 2011 Tohoku Earthquake of Mw 9.0 occurred and its tsunami attacked Japan. The tsunami warning issued by the Japan Meteorological Agency (JMA) was underestimated unfortunately. JMA updated the warning immediately by using tsunami waveform observed by GPS-mounted Buoys. Takahashi and Konuma (2007) pointed out that the present tsunami warning system would be underestimated for huge earthquakes around Mw 9.0. In this study, tsunami numerical experiment for more than three thousands earthquakes in the Nankai Trough was carried out. A model to estimate earthquake magnitude and to avoid the underestimation of tsunami warning by using GPS-mounted Buoys is proposed. And it was shown that the observed water levels by the GPS-mounted Buoys could estimate the maximum water levels at cities.

DOI： 10.2208/kaigan.69.I_406

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Other Link： http://hdl.handle.net/10112/8851

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Terra Scientific Pub. Co  

We use a two-dimensional tsunami sediment transport model to study the source of the 2004 earthquake. To test the model behavior, numerical experiment on sediment deposition and erosion is performed using various hypothetical parameters of tsunami wavelength, topographic slope, and sediment supply. The numerical experiment results show that erosion and deposition are strongly influenced by the tsunami wavelength and the topographic slope. The model is used to compute the spatial distribution of tsunami deposit thickness produced by the 2004 Indian Ocean over an actual elevation datasets in the coastal area of Lhok Nga, Banda Aceh, Indonesia. The model produced simulated tsunami deposits that have similar thicknesses with the measured data along a surveyed transect. Then we estimate a simple fault model for the southern portion of the 2004 earthquake using tsunami sediment transport simulations. The simulated tsunami run-up from the fault model is very close to the measured run-up. This result indicates that a source process of a large earthquake that generates a large tsunami has a potential to be estimated using sediment deposit distribution data.

DOI： 10.5047/eps.2011.10.009

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Language：Japanese   Publisher：土木学会  

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Language：English   Publisher：Japan Society of Civil Engineers  

An earthquake of magnitude 9.0 occurred off the Pacific coast of Tohoku, Japan, on March 11, 2011. It generated a tsunami 130 km off the northern coast of Japan. The tsunami first reached the Japan mainland 20 min after the earthquake and attacked over 1,300 km along the Pacific coast, inundating over 400 km² of land. As of 14 July, estimated fatalities were 16,011 with additional 5,242 missing. This tsunami was the first case that the modern and well-developed tsunami countermeasures faced such an extreme event.<br> A nationwide tsunami survey has been conducted by joint research groups of 299 researchers among 64 different universities/institutes. Inundation heights and run-up heights measured at 5,247 points in total. On the Sendai plain, the maximum inundation height was 19.5 m, and the tsunami propagated as a bore more than 5 km inland. Along the ria coast, about 50-200 km to the north of Sendai, the narrow bays caused focusing tsunami and generated the largest inundation heights and run-ups. The maximum run-up height measured 40.4 m, resulting in the catastrophic destruction of towns and cities.

DOI： 10.2208/kaigan.67.63

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

There is still no tsunami warning system protecting the shores of the Indian Ocean, but imagine that a tsunami warning system had been in operation at the time of the 2004 Indian Ocean Tsunami. What disaster management information would have been issued for this tsunami? This paper first proposes four tsunamimodels based on the earthquake information issued by different institutions. Next, setting these tsunami models as the initial condition, tsunami simulations are conducted to find the height of the tsunami striking the coastline around the Indian Ocean. As a result, it is indicated that because the tsunami model immediately after occurrence of the 2004 Sumatra Earthquake and the Indian Ocean tsunami calculated from this model are underestimated, appropriate tsunami warnings would most probably not have been issued before the 2004 tsunami struck land.

DOI： 10.20965/jdr.2011.p0212

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Language：English   Publisher：Japan Society of Civil Engineers  

Most of hydroelectricity development represented by the dam in our country has almost completed. In comparison with it, the use of ocean energy generation is still a development stage. For this reason, we aim at development of the small hydroelectricity device using a piezo-electric element, it will harness Kármán vortex street which occurred by put the object in flow. In this paper, we perform basic examination by numerical simulation and hydraulic experiment about the relationship between Kármán vortex street and the object shape in flow, and vortex-induced vibration. Then we will make generation experiment based on its results, and suggest suitable model of generation.

DOI： 10.2208/kaigan.66.1286

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Other Link： https://jlc.jst.go.jp/DN/JALC/00358853266?from=CiNii

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Other Link： http://hdl.handle.net/2433/149594

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

The southwestern Pacific Ocean is prone to significant tsunami risk due to giant earthquakes generated near Japan. In this study, two huge tsunamis in the Japan Trench and the Nankai Trough were assumed. They have been called the Sanriku Earthquake Tsunami and the Tonankai-Nankai Earthquake Tsunami. To check the uncertainty of the tsunami model, four more models that intensify the dislocations of half of the tsunami sources were assessed. The computed tsunami energy distributions show that the Sanriku Tsunami propagates mainly toward the central Pacific Ocean and has little effect on the southwestern Pacific countries. On the other hand, the tsunami in the Nankai Trough propagates mainly toward the southwestern Pacific Ocean because of the Mariana Trench. In many cities, the water level exceeds 50 cm. Further, there are some observation stations along the path of the tsunami propagation and they might be useful for a far field tsunami warning system in this region.

DOI： 10.2495/SAFE090461

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Language：English   Publisher：Japan Society of Civil Engineers  

Using the numerical analysis of tsunami run-up and inundation, safety assessment of river levee, damage prediction by tsunami inundation and countermeasures for the safety of residents are considered. For the past examination, fixed bed model were used for the numerical analysis even in the area of river mouth where the sand bar is well developed and the reflection and dissipation of tsunami wave and sand deposit in the channel were prominent. In this study, movable bed model for tsunami wave proposed by Takahashi et al.(1999) was used to analyze the dominant factor for the computational accuracy in order to apply this model to tsunami run up in the river. Kiku-river was chosen for applicability evaluation and tsunami prevention measures were considered through the results obtained from proposed model.

DOI： 10.2208/kaigan.65.301

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Publisher：Japan Society of Civil Engineers  

This study aimes to find out long-term effects of social responses in the 1994 Mindoro tsunami disaster in Oriental Mindoro, Phillipines. In the results, we found out that the resettlement policy toward residents in huge damaged areas by the government was successful so far. Rebuilding houses method "Food for Work" and improvement of infrastructure in the relocation sites were effective against the long-term success of the resettlement policy. In order to continue this success in the future, early issue of land ownership certificate for the residents who have not got ever, and continuance of disaster education in the local high schoole enveloped students' families will be essential.

DOI： 10.2208/jscejseee.65.637

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

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Publisher：Japan Society of Civil Engineers  

An aim of our research is to develop a new tsunami detection system by using an ocean radar. In this study, a back scattering strength is proposed as the new detection index. The index is examined by using the ocean radars data observed in Ishigaki Island and Yonaguni Island. There were 46 earthquakes occurred from April 1, 2004 to March 31, 2006. For the M6.5 earthquake, the back scattering strength became larger rapidly around its epicenter when the main shock occurred. However, the M6.5 is not large for tsunamigenic earthquakes. Then, larger sea surface disturbance due to Typhoon Matsa in 2005 are also analyzed. Accordingly, it is confirmed that the back scattering strength became larger when it passed over the ocean radar observation region.

DOI： 10.2208/proce1989.54.206

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Publisher：Japan Society of Civil Engineers  

In the 2004 Indian Ocean Tsunami, many people who don't know tsunamis were killed by the tsunami. It showed that disaster information is important to mitigate damage caused by tsunamis. To provide appropriate disaster information for the administrators and residents, a tsunami warning system is necessary. A reliability of the system depends largely on its capacity for detecting tsunamis. The present tsunami warning systems use observed seismic waves to detect tsunami source. Then, the present system has risk of underestimating tsunamis due to the great earthquakes of magnitude 9 class right after the main shocks. In this study, we show what tsunami disaster information would be provided, if the present tsunami warning system had been established in the Indian Ocean before 2004.

DOI： 10.2208/proce1989.54.256

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

A tsunamigenic sediment layer has been discovered in fluvio-alluvial sequences on the northern coast of the Marmara Sea, northwestern Turkey. The layer consists of unsorted silty coarse sand including terrestrial molluscs and charcoal fragments. The AMS radiometric ages of the shells have been estimated at around BC 400, AD 300, AD 400, and AD 1000. We propose that a tsunami occurred in the Marmara Sea in the middle of 11th century and invaded the fluvial plains. The older fossils were derived from the underlying horizons, and it is probable that buoyant materials such as terrestrial molluscs and charcoals were isolated from liquefied sediments during submarine sliding. Slope failure of coastal blocks triggered by fault movement generated tsunamis, which might have transported floating materials to the backshore.

DOI： 10.1007/s11069-005-0319-1

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Language：Japanese   Publisher：東北大学  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

2004年9月5日に紀伊半島沖で発生した地震津波について, 津波打ち上げ高および痕跡高に関する現地調査, 津波来襲状況に関する住民のヒアリング調査, 自治体の津波情報の伝達状況に関する調査, およびリアルタイム観測と数値シミュレーションによる解析を実施した. その結果, 本震により発生した津波は伊豆諸島から四国太平洋岸に来襲し, 伊豆諸島で1m未満, 静岡県から和歌山県の太平洋岸にかけて2m程度の津波打ち上げがあったことを確認した. また, 高知県室戸岬沖のGPS津波計では津波のリアルタイム観測に成功し, 数値シミュレーションによる予測結果と良好な一致を示した. 沖合での津波のリアルタイム観測と即時的津波予測の有効性が実証された.

DOI： 10.2208/proce1989.52.1336

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

Field survey for the 2003 Tokachi-oki earthquake tsunami was conducted by the scientists from all over Japan [Tanioka et al., 2004a, b]. Large tsunami heights of about 4 in were observed at Hyakuninhama to the east of Cape Erimo and along the beach between Horokayanto and Oikamanai. Those places are close to the source region of the earthquake. In general, tsunami heights gradually decreased to the east and to the west away from those two locations except at Mabiro where a large tsunami height of about 4m was locally observed. The most intensive tsunami survey was conducted at the Ootsu harbor. The survey results indicate that the quay of the harbor was completely submerged by the tsunami, but the road around the harbor was not. Numerical computation of the 2003 Tokachi-oki tsunami was carried out by solving the nonlinear shallow water equations with a moving boundary condition near the Ootsu harbor. The computed tsunami at the Ootsu harbor well explains the above observations.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TERRA SCIENTIFIC PUBL CO  

A tsunami height survey was conducted immediately after the 2004 off the Kii peninsula earthquakes. Results of the survey show that the largest tsunami height was about 4.6 in locally at Kiho-cho, Mie prefecture. Numerical simulation Of the tsunami due to the earthquake was carried out using the model parameters estimated by NIED. The distribution pattern of the observed tsunami heights along the coast cannot be explained by the computed heights, because the model equation is linear long-wave theory and the run-up computations with a finer grid system are not included in this simulation. In order to explain tsunami run-up heights, it is necessary that the non-linear and run-up computation model Should be used with a finer grid system.

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DOI： 10.2208/proce1989.52.251

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DOI： 10.2208/proce1989.52.266

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DOI： 10.2208/proce1989.52.1341

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Language：Japanese   Publisher：東北大学  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/proce1989.51.1356

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TERRA SCIENTIFIC PUBL CO  

Tsunami height survey was conducted immediately after the 2003 Tokachi-oki earthquake. Results of the survey show that the largest tsunami height was 4 m to the east of Cape Erimo, around Bansei-onsen, and locally at Mabiro. The results also show that the tsunami height distribution of the 2003 Tokachi-oki earthquake is clearly different from that of the 1952 Tokachi-oki earthquake, suggesting the different source areas of the 1952 and 2003 Tokachi-oki earthquakes. Numerical simulation of tsunami is carried out using the slip distribution estimated by Yamanaka and Kikuchi (2003). The overall pattern of the observed tsunami height distribution along the coast is explained by the computed ones although the observed tsunami heights are slightly smaller. Large later phase observed at the tide gauge in Urakawa is the edge wave propagating from Cape Erimo along the west coast of the Hidaka area.

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DOI： 10.2208/prooe.20.21

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DOI： 10.2208/proce1989.51.1316

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

The Minoan Thera eruption of the Bronze Age is the most significant Aegean explosive volcanism. The eruption resulted in caldera collapse. We studied the Minoan volcano-tectonic event from the viewpoint of sedimentology and hydraulics. On the Aegean Sea coast of Turkey and Crete we found traces of tsunamis. The tsunami layers are overlain by felsic tephra. The mineralogical characteristics of volcanic tephra and AMS radiocarbon dating on foraminiferal tests show that the tsunami layers are correlative to the Minoan event. The results of our numerical simulation on the tsunami show that a destructive train of waves caused by the caldera collapse reached the Aegean Sea shore within 2.5 hours and the great surf set up by arrival of waves washed the coast. We conclude that the Minoan tsunami hazards damaged the maritime economy in the coastal areas of Aegean islands and Turkey.

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Language：Japanese   Publisher：消防科学総合センター  

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DOI： 10.2208/proce1989.50.276

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Language：Japanese   Publisher：東北大学  

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Language：Japanese   Publisher：日本自然災害学会  

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

Runup data in Biak Island and its nearby islets are described with discussions of tsunami magnitude and a few characteristics such as witnessed arrival times, wave periods and wave numbers. From an engineering viewpoint, a relation between inundation depth and current velocity on land is also described with relations between inundation depth and degree of damage to houses and between sand erosion depth and current velocity in backshore region, based on data collected from the present and past tsunamis.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOLOGICAL SOC AMERICA, INC  

The Hellenic are is a terrane of extensive Quaternary volcanism. One of the main centers of explosive eruptions is located on Thera (Santorini), and the eruption of the Thera volcano in late Minoan time (1600-1300 B.C.) is considered to have been the most significant Aegean explosive volcanism during the late Holocene. The last eruptive phase of Thera resulted in an enormous submarine caldera, which is believed to have produced tsunamis on a large scale. Evidence suggesting seawater inundation was found previously at some archaeological sites on the coast of Crete; however, the cause of the tsunami and its effects on the area have not been well understood. On the Aegean Sea coast of western Turkey (Didim and Fethye) and Crete (Gouves), we have found traces of tsunami deposits related to the Thera eruption. The sedimentological consequences and the hydraulics of a Thera-caused tsunami indicate that the eruption of Thera volcano was earlier than the previous estimates and the tsunami did not have disruptive influence on Minoan civilization.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Geophysical Union  

DOI： 10.1029/EO081i052p00641-02

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DOI： 10.2208/proce1989.47.336

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Other Link： https://jlc.jst.go.jp/DN/JALC/00368591509?from=CiNii

Language：Japanese   Publisher：Tohoku University  

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Language：English   Publisher：Tohoku University  

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Language：Japanese   Publisher：東北大学大学院工学研究科災害制御研究センター  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/proce1989.46.376

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Other Link： https://jlc.jst.go.jp/DN/JALC/00368588820?from=CiNii

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DOI： 10.2208/proce1989.46.606

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Language：Japanese   Publisher：Tohoku University  

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DOI： 10.2208/proce1989.45.371

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOLOGICAL SOC AMERICA  

Sedimentation processes caused by a modern tsunami have been discussed from the point of view of geologic and numerical investigations of the 1992 Flores tsunami in Indonesia. Geologic evidence on Babi Island shows an invasion of two waves of different direction and magnitude, which resulted in widespread deposition of marine sand on the north and south-southwest shores. On the latter, coarse and well-sorted carbonate sand containing molluscan shells suggests that much more destructive waves swept across the southern coast, as compared with the northern coast, where the deposit included medium carbonate sand with a silty component. A physical explanation for such destructive waves on the southern coast of Babi is provided by a numerical simulation of the tsunami generation and propagation. The geologic and numerical results indicate that an isolated island surrounded by a circular shoreline or reef edge will be subject to the most destructive waves on the coast on the hack side of the island relative to the tsunami source.

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Language：Japanese   Publisher：東北大学  

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Language：Japanese   Publisher：東北大学大学院工学研究科災害制御研究センター  

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DOI： 10.2208/proce1989.43.311

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DOI： 10.2208/proce1989.43.276

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Language：Japanese   Publisher：日本造船学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

This paper presents the second detailed study of sediments deposited by modern tsunamis, the first being that of the Flores (Indonesia) tsunami of December 1992 (Shi et nl., 1995). Sediment cores were collected from areas in which eyewitnesses reported sediment deposition. Grain size analysis shows pronounced vertical variations in grain size as well as changes in standard deviation, skewness and kurtosis that appear to be indicative of complex tsunami flooding. Vertical variations in grain size in individual cores are greater than spatial variations between cores taken along a transect completed perpendicular to the coastline. The Java tsunami-deposited sediments do not show unequivocal evidence of local erosion but instead evidence for sediment transport and deposition is clear and is characterised by dominantly unimodal sediments with fine-tailed distributions. Copyright (C) 1996 Elsevier Science Ltd

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BIRKHAUSER VERLAG AG  

A field survey of the 1992 Flores Island earthquake tsunami was conducted during December 29, 1992 to January 5, 1993 along the north coast of the eastern part of Flores Island. We visited over 40 villages, measured tsunami heights, and interviewed the inhabitants. It was clarified that the first wave attacked the coast within five minutes at most of the surveyed villages. The crust was uplifted west of the Cape of Batumanuk, and subsided east of it. In the residential area of Wuring, which is located on a sand spit with ground height of 2 meters, most wooden houses built on stilts collapsed and 87 people were killed even though the tsunami height reached only 3.2 meters. In the two villages on Babi Island, the tsunami swept away all wooden houses and killed 263 of 1,093 inhabitants. Tsunami height at Riang-Kroko village on the northeastern end of Flores Island reached 26.2 meters and 137 of the 406 inhabitants were killed by the tsumani. Evidence of landslides was detected at a few points on the coast of Hading Bay, and the huge tsunami was probably formed by earthquake-induced landslides. The relationship between tsunami height and mortality was checked for seven villages. The efficiencies of trees arranged in front of coastal villages, and coral reefs in dissipating the tsunami energy are discussed.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BIRKHAUSER VERLAG AG  

Numerical analysis of the 1999 Flores Island, Indonesia earthquake tsunami is carried out with the composite fault model consisting of two different slip values. Computed results show good agreement with the measured runup heights in the northeastern part of Flores Island, except for those in the southern shore of Hading Bay and at Riangkroko. The landslides in the southern part of Hading Bay could generate local tsunamis of more than 10 m. The circular-are slip model proposed in this study for wave generation due to landslides shows better results than the subsidence model, It is, however. difficult to reproduce the tsunami runup height of 26.2 m at Riangkroko, which was extraordinarily high compared to other places. The wave propagation process on a sea bottom with a steep slope, as well as landslides, may be the cause of the amplification of tsunami at Riangkroko. The simulation model demonstrates that the reflected wave along the northeastern shore of Flores Island, accompanying a high hydraulic pressure, could be the main cause of severe damage in the southern coast of Babi island.

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Language：Japanese   Publisher：Tohoku University  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/proce1989.40.181

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On December 12,1992,5 : 29 a.m. UTC (1 : 29 p.m. local time), a magnitude M7.5 (USGS) earthquake struck the eastern region of Flores Island, Indonesia. A highly cooperative international survey team was formed, consisting of twenty scientists and engineers. Our Japanese team visited Indonesia on December 25,1992 to January 10,1993 and managed the field survey on earthquake and tsunami disasters. The first tsunami was reported to reach the shore of Flores Island within five minutes after the earthquake, because it is characterized as an extremely near-source event. About 1,000 people were killed by the tsunami. The maximum runup height measured is 26.2m at Kroko. Through the questionnaire the human behavior at the moment of tsunami attacking was studied. The lessons from the tsunami disaster will be useful for the Tokai tsunami prepardness in Japan.

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Other Link： http://id.nii.ac.jp/1141/00112665/

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DOI： 10.2208/proce1989.40.171

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Language：Japanese   Publisher：東北大学  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/proce1989.46.381

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Language：Japanese   Publisher：独立行政法人防災科学技術研究所  

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Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.1997.0_291_1

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Language：Japanese   Publisher：独立行政法人防災科学技術研究所  

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Language：English   Publisher：BIRKHAUSER VERLAG AG  

A source model for the 1993 Hokkaido Nansei-Oki tsunami must satisfy certain conditions. Such conditions are presented in this paper, and two methods are used to determine the best source model for this event. A trial-and-error method selects DCRC-17a as the best among 24 different models. This model has three fault planes dipping westward. To reproduce well the tide gauge records at two locations, an inversion analysis is used to modify the dislocation of DCRC-17a.

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Language：Japanese   Publisher：地震学会  

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DOI： 10.2208/proce1989.39.231

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