[H-DS06] Tsunami and tsunami forecast

[HDS06-12] Numerical simulation of the 2009 Suruga Bay earthquake tsunami by multiple submarine landslides

*Hideaki Yanagisawa¹, Ikuo Abe², Toshitaka Baba³, Ken Ikehara⁴ (1.Department of regional Management, Faculty of Liberal Arts, Tohoku Gakuin University, 2.Faculty of Social and Environmental Studies, Department of Social and Environmental Studies, Tokoha University, 3.Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 4.Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology)

Keywords:Tsunami, Submarine landslide, Multiple landslides, The 2009 Suruga Bay earthquake, Numerical simulation, Topographic change

The tsunami generated by the 2009 Suruga Bay earthquake with M6.5 recoded a 62 cm (negative wave) and 36 cm water level at Yaizu and Omaezaki port, respectively. This event damaged the water intake pipe on seabed, which could be swiped about 1 km downstream by a mud flow. Although some researchers had tried to simulate the tsunami by earthquake fault models, their results had underestimated the tsunami height. To amplify numerical results, not only earthquake fault model but also the landslide model has been proposed based on the evidence of a mud flow and submarine topography. However, previous models cannot reproduce some characteristics of tsunami tide records in the Suruga Bay. Thus, we try to reproduce characteristics of tsunami tide records using landslide-tsunami integrated model (two-layer model) based on simplified scenarios with referring to the topographic change before and after the event. As results, we clarified that multiple landslides at submarine slope off Yaizu and Oikawa port caused the characteristics of the 2009 event. The results well repoduce not only long-wave component but also short-wave component recorded at the Omaezaki port. This result intends observed short-wave component is one of the unique characteristics of landslide-induced tsunami. From these results, we concluded that the 2009 tsunami event was amplified by multiple submarine landslide.