AbstractThe 2011 Great East Japan Tsunami exposed many hidden weaknesses in Japan's tsunami countermeasures. Since then, improvements have been made both structural measures (numerical simulations, coastal defense structures, building damage assessment and control forests) nonstructural (warning/observation evacuation). This review summarizes the lessons five-year time period after event. After five years, most of from applied, including more realistic simulations using very fine grids,...

The 2016 Fukushima earthquake and tsunami presented several new issues of generation mechanism propagation, as well organizational responses such evacuation procedures dissemination warning. This study focuses on explanations to public interest based the experiences during tsunami: (1) Despite Prefecture's proximity earthquake's epicenter, why was largest wave observed in neighboring Miyagi Prefecture? (2) Why second larger than first? (3) advisory elevated a warning (4) did intrusions into...

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 southern Sanriku Coast of Japan. The simulation verified using observed inundation processes heights, measured topographic deposition. Aerial video footage recorded by Iwate Prefectural Police also used. results show able predict spatial distribution volume erosion deposition Bay, as well processes. effects...

Detailed three-dimensional images of P and S wave velocity Poisson's ratio (σ) the crust upper mantle beneath Kyushu in SW Japan are determined, with a focus on source area 2016 Kumamoto earthquake (M 7.3) that occurred Beppu-Shimabara graben (BSG) where four active volcanoes many faults exist. The took place high-velocity low-σ zone crust, which is surrounded underlain by low-velocity high-σ anomalies mantle. This result suggests that, around earthquake, strong structural heterogeneities...

Abstract. Since the two devastating tsunamis in 2004 (Indian Ocean) and 2011 (Great East Japan), new findings have emerged on relationship between tsunami characteristics damage terms of fragility functions. Human loss to buildings infrastructures are primary target recovery reconstruction; thus, such relationships for offshore properties marine ecosystems remain unclear. To overcome this lack knowledge, study used available data from possible areas (Mangokuura Lake Matsushima Bay) Japan...

Interaction of surface/internal water waves with a floating platform is discussed nonlinearity fluid motion and flexibility oscillating structure. The set governing equations based on variational principle applied to one‐ or two‐layer interacting horizontally very large elastic thin plate the surface. Calculation results surface displacements are compared existing experimental data, where tsunami, in terms solitary wave, propagates across one‐layer plate. We also simulate internal due point...

岩手県陸前高田市における，2011年東北地方太平洋沖地震津波による大規模土砂移動を対象とした再現計算を実施した．その結果，津波の遡上過程や浸水高，地形変化量や海域における堆積土砂の分布傾向を，本計算が良好に再現することを示した．そして，津波による地盤の侵食は，従来の土砂移動を考慮しない解析と比較して陸域における遡上過程を早める効果を有することがわかった．また，2011年東北地方太平洋沖地震津波の第一波目の来襲により高田松原は消失し，特に，引き波時の強い戻り流れにより顕著に侵食されたことを明らかにした．こうした強い戻り流れは，対象地域の地理的特性によって引き起こされる場合がある．すなわち，平野部の奥行きが中規模である地域に津波が来襲する場合，強い戻り流れが生じ，地形変化が大規模化し得る．

Abstract. The 2004 Indian Ocean tsunami and the 2011 Tōhoku earthquake caused large-scale topographic changes in coastal areas. Whereas much research has focused on coastlines that have or had large human populations, little focus been paid to no infrastructure. importance of examining erosional depositional mechanisms events lies rapid reorganization must undertake immediately after an event. A thorough understanding pre-event conditions is paramount natural reconstruction environment. This...

To evaluate tsunami hazards with strong locality in urban areas, this study developed a novel inundation model based on nonlinear shallow water wave equations and porous body (PBM). By applying kinematic boundary condition that includes both porosity surface permeability of the medium, proposed could accurately incorporate geometric effects such as flow anisotropy caused by distributions buildings. The PBM demonstrated good accuracy for heights around buildings near coastline conventional...

津波氾濫・土砂移動・漂流物移動による複合現象を予測・評価するために津波統合モデルを開発し,狭窄部を有する湾に特有の複合的な津波被害拡大のシナリオを明らかにした.宮城県気仙沼市では,湾狭窄部の侵食により,特に湾奥における津波ハザードが拡大したことがわかった.その結果,船舶の漂流距離は長距離化した.更に,木造家屋の被害実績と数値解析結果に基づき,建物被害関数を推定したところ,土砂移動の影響により200~1800棟(被害実績の5~40%)の木造家屋が流出したと推定された.また,従来手法に基づく津波被害関数では,当該地域における被害規模の推定精度は良好である一方,沿岸付近の被害を過小評価し,内陸では過大評価になることがわかった.

宮城県岩沼市における海岸林の津波減衰・減災機能，並びに，海岸林と複数の防災施設との組み合わせによる減衰機能について，津波数値解析に基づき検討した．まず，海岸林が発揮し得る，浸水深や流速の減衰効果，津波到達時間の遅延効果および建物・人的被害率の低減効果を評価した．次に，現況の多重防御整備事業が，2011年東北津波に対しても一定の津波減衰効果を有することを確認し，垂直避難場所としての避難丘やそれらを結ぶ園路といった防災施設を多段的に整備することにより，特に，背後地における流速の低減および津波到達時間の遅延に対して効果的であり，樹木倒伏の抑制にも繋がることがわかった．避難丘については，防潮堤の背後近くでの整備が有効であった．これら防災施設の特性を吟味し組み合わせることが津波減衰に対して有効である．

Numerical solutions of surface and internal solitary waves are obtained through a new method, where advection equations on physical quantities including surface/interface displacements velocity potential solved to find convergent by applying the Newton-Raphson method. The nonlinear wave derived using variational principle adopted as fundamental in present study. Surface proposed method compared with corresponding theoretical solutions, well numerical Euler equations, verify accuracy...

狭窄部を有する宮城県気仙沼湾における東日本大震災の津波・土砂移動を対象として,津波土砂移動モデルによる侵食及び堆積の過小評価の要因を推定し,従来モデルの改善を図った.湾狭窄部では強い非定常流れが生じていたことが数値的に確認された.そのため,従来の飽和浮遊砂濃度モデルでは巻上砂量が過剰に抑制され,地形変化の過小評価の一因になったと推定された.そこで,Log-wake則による実験式とカルマン数の変化を導入した,強い非定常流れに適用可能な飽和浮遊砂濃度式を提案した.岩盤層の取扱いや湾奥での堆積土砂量には依然課題が残ったが,提案した飽和濃度式は期待通り機能し,地形変化の再現性が改善された.強い非定常流れが生じ得る複雑地形の地形変化の再現性のみならず,浸水範囲や被害評価等の精度向上にも繋がると期待される.

Abstract Tsunamis generated by atmospheric pressure waves due to a volcanic eruption were investigated based on both the proposed estimation formulas and numerical calculations. First, assuming linear shallow water conditions, for maximum possible amplitude resonance distance. Second, fundamental properties of tsunamis examined numerically using nondispersion weak dispersion models. Based results, ridge shelf can amplify beyond limits Proudman resonance. The estimated determined amplitudes...

The internal waves in the two-layer systems have been numerically simulated by solving set of nonlinear equations consideration both strong nonlinearity and dispersion waves. After comparison between numerical results BO solitons, as well experimental data, propagating over uniformly sloping beach are including cases mild long slopes. show remarkable shoaling after interface touches critical level. In lower layer, horizontal velocity becomes larger than local linear celerity shallow water...

A set of nonlinear surface/internal-wave equations, which have been derived on the basis variational principle without any assumptions concerning wave nonlinearity and dispersion, is applied to compare numerical results with experimental data surface/internal waves propagating through a shallow- or deep-water region in tank. Internal over submerged breakwater uniformly sloping beach are also simulated. The internal progressive shows remarkable shoaling when interface reaches critical level,...

How can the global tsunami amplitude distribution caused by air pressure waves from 2022 Tonga eruption be explained? We first propose estimation formulas expressing maximum possible and resonance distance of tsunamis. The clarify both static dynamic effects in Proudman resonance. Then, based on these formulas, we present hazard maps world's oceans for different wave speeds, considering water depths. also indicate excitation length each path. Using maps, identify ocean regions that trigger...

Abstract. The 2004 Indian Ocean Tsunami and the 2011 Great East Japan earthquake tsunami caused large-scale topographic changes in coastal areas. Whereas much research has focused on coastlines that have or had large human populations, little focus been paid no infrastructure. importance of examining erosional depositional mechanisms events lies rapid reorganisation must undertake immediately after an event. Through understanding precursor conditions to this is paramount reconstruction...