Japan Geoscience Union Meeting 2015

Presentation information

International Session (Poster)

Symbol S (Solid Earth Sciences) » S-SS Seismology

[S-SS02] Frontier studies on subduction zone megathrust earthquakes and tsunamis

Mon. May 25, 2015 6:15 PM - 7:30 PM Convention Hall (2F)

Convener:*Kyuichi Kanagawa(Graduate School of Science, Chiba University), Demian Saffer(Dept. of Geosciences, The Pennsylvania State University, USA), Michael Strasser(Geological Institute, Seiss Federal Insitute of Technology ETH Zurich), Yasuhiro Yamada(Depertment of Urban Management Engineering, Kyoto University), Shuichi Kodaira(Institute for Research on Earth Evolution Japan Agency for Marine-Earth Science and Technology), Ryota Hino(International Research Institute of Disaster Science, Tohoku University), Kohtaro Ujiie(Graduate School of Life and Environmental Sciences, University of Tsukuba), Yoshihiro Ito(Disaster Prevention Research Institute, Kyoto University)

6:15 PM - 7:30 PM

[SSS02-P01] Investigation of the Behavior of Shallow Parts of Mega-Thrust Earthquake Faults Based on Dynamic Rupture Simulations

*Kenichi TSUDA1, Toru ISHII2, Sachio OGAWA1, Takahide WATANABE1, Hiroaki URATANI3, Satoshi IWASE3, Jean paul AMPUERO4 (1.Ohsaki Research Institute, 2.Shimizu Corporation, 3.Chubu Electric Power Company, 4.Seismological Lab, California Institute of Technology)

Recent inter-plate mega-thrust earthquakes, such as the 2011 Off the Pacific Coast of Tohoku earthquake (Tohoku Earthquake, Mw 9.0), the 2010 Maule, Chile earthquake (Mw 8.8) and the 2004 Sumatra earthquake (Mw 9.2), revealed some special features of ruptures, such as very large slip (order of several ten meters) and limited short period seismic radiations close to the trench. However, the mechanical origin of these phenomena has not been clarified yet.
In this study, we carry out simulations of the rupture process of large mega-thrust earthquakes based on dynamic models to understand the behavior of shallow parts of the faults. The model is governed by a slip-dependent friction law (Ida, 1972). The simulations employ the 3D Spectral Element Method (Galvez et al., 2014), which is numerically stable and accurate even for subduction models with low dipping angle. Based on these simulations, we explored some possible hypothesis for the generation of large slip on the shallow parts of the faults: large stress drop and thermal pressurization (e.g., Bletery et al., 2014). The results of our dynamic simulations provide useful clues to understand more generally the behavior of shallow parts of the mega-thrust earthquake faults.