Source Reconstruction of the 1969 Western Sulawesi, Indonesia, Earthquake and Tsunami


Simultaneous Inversion of Ocean Bottom Pressure and Electromagnetic Tsunami Records for the 2009 Samoa Earthquake

Journal of Geophysical Research. Solid Earth


An earthquake-triggered submarine mass failure mechanism for the 1994 Mindoro tsunami in the Philippines: Constraints from numerical modeling and submarine geomorphology


Numerical estimation of a tsunami source at the flexural area of Kuril and Japan Trenches in the fifteenth to seventeenth century based on paleotsunami deposit distributions in northern Japan


Numerical experiments on tsunami flow depth prediction for clustered areas using regression and machine learning models


Probabilistic tsunami hazard assessment based on the Gutenberg Richter law in eastern Shikoku


Variation analysis of multiple tsunami inundation models


Impact of ionosphere on InSAR observation and coseismic slip inversion: Improved slip model for the 2010 Maule, Chile, earthquake


Frequency dispersion amplifies tsunamis caused by outer-rise normal faults

Although tsunamis are dispersive water waves, hazard maps for earthquake-generated tsunamis neglect dispersive effects because the spatial dimensions of tsunamis are much greater than the water depth, and dispersive effects are generally small. Furthermore, calculations that include non-dispersive effects tend to predict higher tsunamis than ones that include dispersive effects. Although non-dispersive models may overestimate the tsunami height, this conservative approach is acceptable in disaster management, where the goal is to save lives and protect property. However, we demonstrate that offshore frequency dispersion amplifies tsunamis caused by outer-rise earthquakes, which displace the ocean bottom downward in a narrow area, generating a dispersive short-wavelength and pulling-dominant (water withdrawn) tsunami. We compared observational evidence and calculations of tsunami for a 1933 M 8.3 outer-rise earthquake along the Japan Trench. Dispersive (Boussinesq) calculations predicted significant frequency dispersion in the 1933 tsunami. The dispersive tsunami deformation offshore produced tsunami inundation heights that were about 10% larger than those predicted by non-dispersive (long-wave) calculations. The dispersive tsunami calculations simulated the observed tsunami inundation heights better than did the non-dispersive tsunami calculations. Contrary to conventional practice, we conclude that dispersive calculations are essential when preparing deterministic hazard maps for outer-rise tsunamis.


Numerical simulation of urban inundation processes and their hydraulic quantities - Tsunami analysis hackathon theme 1 -

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.


Deep investigations of outer-rise tsunami characteristics using well-mapped normal faults along the Japan Trench


Synthesizing sea surface height change including seismic waves and tsunami using a dynamic rupture scenario of anticipated Nankai trough earthquakes


Modeling of a dispersive tsunami caused by a submarine landslide based on detailed bathymetry of the continental slope in the Nankai trough, southwest Japan


A nonlinear parametric model based on a power law relationship for predicting the coastal tsunami height


Motion and Speed of the Frail Elderly During Evacuation Process

Journal of Japan Society for Natural Disaster Science


NUMERICAL STUDY ON VARIABILITY OF TSUNAMI INUNDATION PROCESS INDUCED BY A GROUND LIQ-UEFACTION IN TOKUSHIMA CITY

液状化に伴う沈下を考慮した徳島県東部での津波浸水過程の数値的検討

A tsunami simulation with a ground liquefaction was conducted for the evaluation of an effect on the variability of the tsunami inundation process caused by the ground deformation. We developed a new correction method to calculate a change of ground elevation by a ground liquefaction using the result of the simplified method and the result of FEM by FLIP. The tsunami simulation was conducted by JAGRUS. As a result, the inundation process and the arrival time of Tsunami were changed by a ground liquefaction around small rivers and banking structures because the tsunami runs up through small rivers and is trapped by roads and rail tracks. There were areas where the arrival time of the tsunami reached at most 10 minutes earlier. The numerical results suggested that ground conditions could change the tsunami prediction result drastically and we should start to escape disaster as soon as possible.

徳島市を対象に，液状化による地盤沈下を考慮した津波浸水計算を行い，液状化による津波浸水過程への影響を評価した．地盤沈下量は，中央防災会議による予測結果を有限要素解析(FLIP)の結果を用いて補足することで求めた．津波浸水予測にはJAGRUSを用いた．その結果，津波の浸水過程と到達時刻は，液状化による沈下を考慮した場合，内陸に向かう小河川の近くや，道路や鉄道線路といった人工地形の周辺で変化した．このような浸水過程の変動特性を有する場所では，津波到達時刻が最大で10分程度早まることもあった．これは特定の条件下での解析結果であるため，可能性の一つではあるが早期避難の重要性を改めて示す結果である．

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)

土木学会論文集B2(海岸工学)


Development of semi-real-time tsunami monitoring and calculation system on ocean-bottom stations off the Kii peninsula, southwest Japan


新地球シミュレータによる高分解能・量的津波シミュレーョン

新地球シミュレータによる高分解能・量的津波シミュレーョン

ハイパフォーマンスコンピューティングと計算科学シンポジウム論文集

ハイパフォーマンスコンピューティングと計算科学シンポジウム論文集


Parallel-algorithm Extension for Tsunami and Earthquake-cycle Simulators for Massively Parallel Execution on the K Computer

The International Journal of High Performance Computing Applications


Large-scale, high-speed tsunami prediction for the great Nankai trough earthquake on the K computer


Time reverse imaging for far-field tsunami forecasting: 2011 Tohoku earthquake case study, Geophys


Tsunami waveform inversion for sea surface displacement following the 2011 Tohoku earthquake: Importance of dispersion and source kinematics

Journal of Geophysical Research. Solid Earth


Parallel Implementation of Dispersive Tsunami Wave Modeling with a Nesting Algorithm for the 2011 Tohoku Tsunami


Advanced Real Time Monitoring System and Simulation Researches for Earthquakes and Tsunamis in Japan, in V. S.-Fandiño et al. (ed.)

Post-Tsunami Hazard Restoration and Reconstruction


Development and application of an advanced ocean floor network system for meagthrust earthquakes and tsunamis'', Seafloor Observatories


The possibility of deeper or shallower extent of the source area of Nankai Trough earthquakes based on the 1707 Hoei tsunami heights along the Pacific and Seto Inland Sea coasts, southwest Japan


Tsunami Inundation Modeling of the 2011 Tohoku Earthquake Using Three-Dimensional Building Data for Sendai, Miyagi Prefecture, Japan

Tsunami Events and Lessons Learned, Advances in Natural and Technological Hazards Research


Near-field tsunami amplification factors in the Kii Peninsula, Japan for Dense Oceanfloor Network for Earthquakes and Tsunamis (DONET)


Micro-bathymetric Evidence for the Effect of Submarine Mass Movement on Tsunami Generation During the 2009 Suruga Bay Earthquake, Japan

Submarine mass movements and their consequences, Advances in Natural and Technological Hazards Research


Discovery of Submarine landslide Evidence Due to the 2009 Suruga Bay Earthquake


Dispersive tsunami of the 2010 Chile earthquake recorded by the high-sampling-rate ocean-bottom pressure gauges


Afterslip distribution following the 2003 Tokachi-oki earthquake: An estimation based on the Green's functions for an inhomogeneous elastic space with subsurface structure


長期湛水被害からの災害対応・復旧のあり方に関する研究―南海地震による高知市を事例として―


2009年8月11日に駿河湾で発生した地震による深層水取水管の被災とその要因

2009年8月11日に駿河湾で発生した地震による深層水取水管の被災とその要因

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)

土木学会論文集B2(海岸工学)


Ocean-bottom pressure variations during the 2003 Tokachi-oki earthquake

Nonlinear Wave Dynamics, World Scientific


Validation and Joint Inversion of Teleseismic Waveforms for Earthquake Source Models Using Deep Ocean Bottom Pressure Records: A Case Study of the 2006 Kuril Megathrust Earthquake


The Effect of the Great Barrier Reef on the Propagation of the 2007 Solomon Islands Tsunami Recorded in Northeastern Australia


Development of Long-period Ground Motions from the Nankai Trough, Japan, Earthquakes: Observations and Computer Simulation of the 1944 Tonankai (Mw 8.1) and the 2004 SE Off-Kii Peninsula (Mw 7.4) Earthquakes


Effect of elastic inhomogeneity on the surface displacements in the northeastern Japan: Based on three-dimensional numerical modeling


High precision slip distribution of the 1944 Tonankai earthquake inferred from tsunami waveforms: Possible slip on a splay fault


New discoveries in dynamics of an M8 earthquake -Phenomena and their implications from the 2003 Tokachi-oki earthquake using a long term monitoring cabled observatory


A cause of rupture segmentation and synchronization in the Nankai trough revealed by seismic imaging and numerical simulation

Journal of Geophysical Research. Solid Earth


Transient thermal response in ocean bottom pressure measurement


Offshore geodetic data conducive to the estimation of the afterslip distribution following the 2003 Tokachi-oki earthquake


Contiguous rupture areas of two Nankai Trough earthquakes revealed by high-resolution tsunami waveform inversion


Compound fault rupture during the 2004 off the Kii Peninsula earthquake ( M 7.4) inferred from highly resolved coseismic sea-surface deformation


Tsunami source of the 2004 off the Kii-Peninsula earthquakes inferred from offshore tsunami and coastal tide gauges


Earthquake swarms preceding the 2000 eruption of Miyakejima volcano, Japan


A numerical simulation of earthquake cycles along the Nankai trough in southwest Japan: Lateral variation in frictional property due to the slab geometry controls the nucleation position


Intra-plate seismicity in the subdcuting Philippine Sea Plate, southwest Japan: magnitude-depth correlations

Physics of the Earth and Planetary Interiors


Tsunami magnitude determined from ocean-bottom pressure gauge data around Japan


The slip distribution of the 1946 Nankai earthquake estimated from tsunami inversion using a new plate model


The 1946 Nankaido earthquake and segmentation of the Nankai Trough


The Influence of Philippine Sea Plate Structure on Great Nankai Trough Earthquakes Inferred from the Rupture Process of the 1946 Nankai Earthquake

1946年南海地震震源過程から推定された南海トラフ巨大地震に対するフィリピン海プレート形状の影響(<特集>次の南海トラフ巨大地震に備えて)

By carefully analyzing the source process of the 1946 Nankai earthquake and its correlation with plate boundary structure, we attempt to explain the occurrence pattern of historical earthquakes in the Nankai Trough, in which great earthquakes tend to rupture separately either the western or eastern portions of the Nankai Trough. The source process of the 1946 earthquake consists of two major subevents, each corresponding to segments A and B, defined by Ando (1975), which have long been thought to correspond to units of earthquake rupture in the western Nankai Trough. Furthermore, rupture in each subevent begins near the eastern edge of the respective segment, where there are pronounced contortions of the plate boundary : a subducting seamount chain off Cape Muroto and a rapid change in subduction angle beneath the Kii Peninsula. We suggest that these seismotectonic features of the plate boundary shape control to some extent the pattern of great earthquake occurrence in the Nankai Trough.


Deformation of a seamount subducting beneath an accretionary prism: Constraints from numerical simulation


Numerical Experiments of ShearDeformation with Frictional Heating

摩擦熱を考慮した剪断変形のシミュレーション

We develop a thermal-mechanical model for describing the formation of shear zones. We consider shear deformation of a two-dimensional rectangular region composed of a viscous fluid under a constant velocity at the boundary. Viscosity of the material is assumed to depend only on temperature for simplicity. In order to enhance the shear deformation, we included a small inclusion whose viscosity differs from that of the surrounding material. We carried out time-marching simulations and monitored the evolution of temperature and strain around the inclusion. Our results show that the deformation localizes in a narrow region when sufficient heat is generated by viscous dissipation. In the zone of localized deformation, temperature increases by several hundred degrees owing to strong dissipative heating. We found that the zone of localized deformation develops in the region where the greatest heat is generated at the initial stage of evolution. The zone of localized deformation pierces the inclusion when the inclusion is weaker than the surrounding material, while it develops away from the inclusion when the inclusion is stiffer than the surrounding material. These findings, though qualitatively, suggest that heating by viscous dissipation may play an important role in the formation of decollements around subducted seamounts.

Bulletin of the Earthquake Research Institute, University of Tokyo


堤体基礎の地震動脆弱性が津波氾濫解析に与える影響に関する検討

堤体基礎の地震動脆弱性が津波氾濫解析に与える影響に関する検討

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)

土木学会論文集B2(海岸工学)


2次元差分法による津波遡上 解析における建築物・堤防のモデル化忠実度が与える差異

Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE))

土木学会論文集A1(構造・地震工学)


Social Implementation of Tsunami Prediction System on Wakayama by Using DONET Information

DONET観測情報を活用した 津波予測システムの社会実装-和歌山県の事例-

High possibility of occurrence of earthquake with M9 or lager in the Nankai subduction zone was pointed out by Cabinet Office of Japanese government. Local governments along the area revised estimation of tsunami damages and attempt to reconstruct action plans for the disaster prevention. However, according to Cabinet office of Japanese government, the coastal area near the rupture zone receives huge tsunami within a few minutes after the earthquake happens. To take actions against the severe situation, we need a high-speed, and high-accurate tsunami prediction system. Baba et al. (2014) investigated the possibility for use of a concept of tsunami amplification in the early tsunami prediction. They computed tsunami waveforms at the twenty pressure gauges of dense ocean floor network system for earthquakes and tsunamis (DONET) and at prediction points near shore. They found clear correlations between them because tsunami height basically depends on the topography (bathymetry) during its propagation. In this study, an early tsunami prediction system using the concept of tsunami amplification was societally implemented in 6 regional areas in Wakayama Prefecture. We constructed a tsunami database that contains pre-computed tsunamis offshore and nearshore from 1506 earthquake scenarios may occur in the Nankai subduction zones. The new system detects first arrivals of earthquake and tsunami from DONET data in real time, and calculate average value of absolute observed pressure values among twenty DONET stations. The value is used to select an appropriate scenario from the tsunami database. Prediction accuracy of the system was also investigated by using cases of the 1944 Tonankai earthquake and the scenario earthquake provided by the Cabinet office. As a result, we found that predicted inundation area to be overestimated as the safety of the prediction.

南海トラフの沈み込み帯において，M9クラス巨大地震とそれにともなう巨大津波の発生の可能性が内閣府により指摘されて久しい．この津波被害想定によると，地震域近傍の沿岸地域では地震発生から数分後に巨大な津波が到達してしまうため，津波防災に向けた行動計画の再構築や人的被害軽減のための迅速な対応策の検討が極めて重要になる．その対応策のひとつとして，高速かつ高精度な即時津波予測が有効と考えられる．本研究では，地震と津波観測に向けた稠密海底観測網(DONET)による沖合観測網を利用した即時津波予測システムを構築し，和歌山県沿岸6地域において実装を行い，その有効性の検討を行った．本システムにより，地震と津波の初動到達時間を即時評価できること，沿岸津波高や浸水域の即時予測が可能であることを示した．さらに，1944年昭和東南海地震の事例と内閣府のM9クラス巨大地震の波源シナリオを用いて本システムの予測精度を検証した．本システムで即時予測される沿岸津波高や浸水域面積はやや過大評価傾向にあるものの，おおむね安全側の予測結果となり，津波防災上有効なシステムであることを示した．

Journal of Japan Society for Natural Disaster Science


Selection of Tsunami Observation Points Suitable for Database-Driven Prediction


Tsunami Analysis Method with High-Fidelity Crustal Structure and Geometry Model


Real-Time Tsunami Prediction System Using DONET


Preliminary Study on Long-Term Flooding After the Tsunami.


Natural Hazards and Earth System Sciences


Accurate numerical simulation of the far-field tsunami caused by the 2011 Tohoku earthquake, including the effects of Boussinesq dispersion, seawater density stratification, elastic loading, and gravitational potential change


Maximum tsunami height prediction using pressure gauge data by a Gaussian process at Owase in the Kii Peninsula, Japan, Mar


徳島市を対象とした津波による流入水の堤外排水シミュレーション

徳島市を対象とした津波による流入水の堤外排水シミュレーション

土木学会論文集B2(海岸工学)


非線形分散波理論による2011年東北地方太平洋沖地震津波の計算

非線形分散波理論による2011年東北地方太平洋沖地震津波の計算


Interview Investigation about Evacuation Behavior of Residents in the Naka River Area in the Typhoon No.1411 and No.1511

2014年台風11号と2015年台風11号における那賀川流域住民の避難行動に関するヒアリング調査

平成27年自然災害フォーラム論文集

平成27年自然災害フォーラム論文集