Tohoku J. Exp. Med., 2015 October, 237(2)

Invited Review

Aftereffects of Subduction-Zone Earthquakes: Potential Tsunami Hazards along the Japan Sea Coast

KOJI MINOURA,1 DAISUKE SUGAWARA,2 TOHRU YAMANOI3 and TSUTOMU YAMADA4

1Tohoku University, Sendai, Miyagi, Japan
2International Research Institute of Disaster Science, Tohoku University, Sendai, Miyagi, Japan
3Faculty of Science, Yamagata University, Yamagata, Yamagata, Japan
4Institute of Geology and Paleontology, Graduate School of Science, Tohoku University, Sendai, Miyagi, Japan

The 2011 Tohoku-Oki Earthquake is a typical subduction-zone earthquake and is the 4th largest earthquake after the beginning of instrumental observation of earthquakes in the 19th century. In fact, the 2011 Tohoku-Oki Earthquake displaced the northeast Japan island arc horizontally and vertically. The displacement largely changed the tectonic situation of the arc from compressive to tensile. The 9th century in Japan was a period of natural hazards caused by frequent large-scale earthquakes. The aseismic tsunamis that inflicted damage on the Japan Sea coast in the 11th century were related to the occurrence of massive earthquakes that represented the final stage of a period of high seismic activity. Anti-compressive tectonics triggered by the subduction-zone earthquakes induced gravitational instability, which resulted in the generation of tsunamis caused by slope failing at the arc-back-arc boundary. The crustal displacement after the 2011 earthquake infers an increased risk of unexpected local tsunami flooding in the Japan Sea coastal areas.

Key words —— aseismic tsunami; Japan Sea; numerical simulation; slope failing; subduction-zone earthquake

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Tohoku J. Exp. Med., 2015, 237, 91-102

Correspondence: Koji Minoura, Tohoku University, Sendai, Miyagi, Japan.

e-mail: minoura@m.tohoku.ac.jp