Japan Geoscience Union Meeting 2015

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International Session (Oral)

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

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

Mon. May 25, 2015 11:00 AM - 12:45 PM IC (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), Chair:Yoshihiro Ito(Disaster Prevention Research Institute, Kyoto University), Yasuhiro Yamada(Japan Agency for Marine-Earth Science and Technology)

11:30 AM - 11:45 AM

[SSS02-09] Rupture dynamics inferred from early stage of the 2011 great Tohoku-oki earthquake

Ryosuke ANDO1, *Takahiko UCHIDE2 (1.School of Science, University of Tokyo, 2.Geological Survey of Japan, AIST)

Keywords:Tohoku-oki earthquake, dynamics, rupture, friction, inversion, simulation

The occurrence of the 2011 M 9.0, Japan, Tohoku-oki earthquake gives us a unique opportunity to investigate the detailed process of the initiation and propagation of a rupture during a gigantic earthquake. It is observed that the mainshock of the Tohoku-oki earthquake was triggered by the M7 foreshock with time delay of two days occurred near the hypocenter of the mainshock. Therefore, it is expected that the early stage of the mainshock rupture reflects perturbations caused by the foreshock. In order to test this hypothesis, we examine the stress changes during the dynamic rupture propagation of this event. We used the kinematically inverted slip profile obtained by Uchide (2013), JGR, which conducted the multi-scale seismic slip inversion focusing on the first few ten seconds of the mainshock; he showed that the slip profiles around the hypocenter exhibited high-speed rupture propagations. We calculate the dynamic stress changes on the fault plane given the inverted slip profile by applying the 3-D elasto-dynamic boundary integral equation method (Ando and Okuyama, 2010, GRL). The calculated stress changes shows generally the slip weakening behavior consistent with the occurrence of the high speed rupture. The obtained stress change also shows heterogeneous distribution over the fault area, which might reflect the stress perturbation existed before the mainshock.