scholarly journals TSUNAMI INUNDATION SIMULATIONS IN URBAN TOPOGRAPHY

Author(s):  
Takuya Miyashita ◽  
Nobuhito Mori

The inundation of the 2011 Tohoku Earthquake Tsunami showed complex behavior over the land. According to the surveys of the Tohoku Earthquake Tsunami in 2011, the behavior of tsunami in urban areas was different from that in rural areas and the damage was not only dependent on the inundation heights but also the local momentum. The buildings are commonly excluded and smoothed off in the topography in the conventional inundation simulation but it’s important to understand the local characteristics of tsunami run-up in urban areas. The purpose of this study is to understand and validate numerical models of tsunami in the urban area.

2016 ◽  
Vol 32 (4) ◽  
pp. 1989-2007 ◽  
Author(s):  
Kohji Tokimatsu ◽  
Michitaka Ishida ◽  
Shusaku Inoue

A simulation of the tsunami run-up during the 2011 Great Tohoku Earthquake was performed to investigate the mechanisms and differences in overturning failures of buildings in Onagawa, based on a two-dimensional (2-D) shallow water equation with video evidence recorded in the town as reference. The time histories of inundation depth and flow velocity predicted by the analysis enable one to develop a simplified method to estimate the hydrodynamic and buoyant forces acting on a building, as well as its factors of safety against sliding, uplift, and overturning in the time domain. This method was applied to five well-documented cases of buildings that did or did not overturn during the tsunami. Results showed that the proposed method is capable of predicting the differences in building performance qualitatively, including the likelihood, time, and direction of toppling. The results also suggested that the seaward overturning of one building is likely due to its specific topographical location with a hill closely behind that makes the tsunami load significantly less during run-up than during backwash.


2016 ◽  
Vol 10 (05) ◽  
pp. 1640020 ◽  
Author(s):  
Masaharu Isshiki ◽  
Mitsuteru Asai ◽  
Shimon Eguchi ◽  
Hideyuki O-Tani

The 2011 off the Pacific coast of Tohoku Earthquake was one of the most powerful earthquakes on record in Japan and the huge tsunami caused by the earthquake inflicted extensive damage to the coastal areas of the Tohoku region. To form safe coastal areas, countermeasures against disaster should be developed considering not only tangible infrastructures including breakwater and bridges but also intangible measures including education on disaster prevention and the development of hazard maps. The tsunami run-up analysis is expected to play a role as one of the countermeasures against tsunami. In this research, we aim to establish a tool to effectively analyze the tsunami run-up in urban areas based on the Smoothed particle hydrodynamics (SPH) method. And then, we propose a series of pre-process procedures to develop a detailed geography analysis model that reflects the geography, elevation, and exterior shapes of buildings by referring to 3D location information and digital elevation model data obtained from a geographical information system. Finally, we established a photorealistic visualization method so that citizen can understand the tsunami phenomenon intuitively.


2015 ◽  
Vol 124 (2) ◽  
pp. 177-192 ◽  
Author(s):  
Nobuhisa MATSUTA ◽  
Yasuhiro SUZUKI ◽  
Nobuhiko SUGITO ◽  
Takashi NAKATA ◽  
Mitsuhisa WATANABE

2013 ◽  
Vol 8 (4) ◽  
pp. 573-583 ◽  
Author(s):  
Yusuke Suga ◽  
◽  
Shunichi Koshimura ◽  
Ei-ichi Kobayashi ◽  
◽  
...  

Drifting ship due to tsunami inundation flow may cause additional damage in harbor area. Many drifting ships were found in the 2011 Great East Japan earthquake tsunami and these caused various problems (damage of ships themselves, striking other structures and obstacle for restoration). In this sense, it is very important for disaster prevention to predict the drifting motion of a large ship by tsunami current. This study aims to simulate the drifting motion of ships by the 2011 Tohoku earthquake tsunami in Kesennuma harbor, Miyagi Prefecture. First, we simulated the hydrodynamic features of the 2011 tsunami by numerical simulation. Secondly, we analyzed the drifting motion of large ships using the result of tsunami numerical simulation. In the analysis, several test cases were conducted by changing parameter and initial position of the ship. Then we verified the results of the ship drifting simulation by comparing with actual grounding position of ships. Throughout the comparisons and verifications, we found the grounding position by the simulation was generally consistent with actual position of ships. Although it is necessary to verify the drifting route of ships, the results suggest that this model is beneficial for future disaster prevention.


Author(s):  
Hideo Matsutomi ◽  
Fumiko Konno

For the sophistication of the tsunami load, future and historical tsunami scale evaluations, the dependency of the density of tsunami inundation water with sediment on the hydraulic quantities, and then the dependencies of the tsunami run-up distance, sediment deposit distance, mean sediment deposit thickness on the density of the tsunami inundation water are examined through a devised small-scale hydraulic experiment. Within the experimental range of this study, it is verified that the density of the tsunami inundation water depends on the Froude number of the incident tsunami inundation flow and the sediment grain size, and the relative tsunami run-up distance (= the run-up distance of the inundation water with sediment/the run-up distance of the inundation water without sediment (= fresh water)), ratio of the tsunami sediment deposit distance to the tsunami run-up distance, ratio of the mean tsunami sediment deposit thickness to the tsunami sediment deposit distance depend on the density of the tsunami inundation water, and four empirical expressions for those dependencies are proposed.


2012 ◽  
Vol 7 (sp) ◽  
pp. 476-484 ◽  
Author(s):  
Takaaki Uda ◽  
◽  
Kazuya Sakai ◽  
Yukiyoshi Hoshigami ◽  
Yasuhito Noshi ◽  
...  

The massive earthquake with a magnitude of 9.0 occurred at 14:46 on March 11, 2011, with an epicenter 130 km offshore from the Oshika Peninsula in Japan’s northeastern Miyagi Prefecture. After the earthquake, large tsunamis were generated owing to abrupt crustal subsidence and uplift, which inundated Japan’s eastern Pacific Ocean coastline. We carried out field observations to investigate the deformation of a previous river-mouth bar by comparing oblique photographs, and investigated the damage to seawalls and the tsunami inundation depth on the Iwama-Sanuka coast, located north of the Same River in southern Fukushima Prefecture. Here, the results of the field observations on the deformation of the sandy beach and the inundation of the Iwama-Sanuka coast are reported.


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