Japan Geoscience Union Meeting 2016

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Oral

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

[S-SS27] Fault Rheology and Earthquake Physics

Thu. May 26, 2016 1:45 PM - 3:10 PM Convention Hall A (2F)

Convener:*Takeshi Iinuma(National Research and Development Agency Japan Agency for Marine-Earth Science and Technology), Yuko Kase(Geological Survey of Japan, AIST), Ryosuke Ando(Graduate School of Science, University of Tokyo), Wataru Tanikawa(Japan Agency for Marine-Earth Science and Technology, Kochi Instutute for Core Sample Research), Hideki Mukoyoshi(Department of Geoscience Interdisciplinary Graduate School of Science and Engineering, Shimane University), Chair:Takeshi Iinuma(National Research and Development Agency Japan Agency for Marine-Earth Science and Technology), Takanori Matsuzawa(National Research Institute for Earth Science and Disaster Prevention)

2:00 PM - 2:15 PM

[SSS27-21] The effect of heterogeneous crust on earthquakes:a case study of the 2011 North Nagano earthquake

*Takashi Miyatake1 (1.Earthquake Research Institute, University of Tokyo)

Keywords:crustal structure, fault stress, asperity

We investigated the effects of heterogeneous crustal structure on earthquake rupture of the 2011 North Nagano earthquake. Using a 3D crustal structure model (Matsubara et al.,2008) we calculate stress distribution by solving static equation of motion. The finite difference method with grid size of 0.1km is used, where the computational space is 100km x 100km x 50km. Displacement boundary condition is applied. Since absolute value of boundary displacement is unknown, relative values of stress components, and the stress ratio, i.e., (fault shear stress) / (fault normal stress) are discussed. Because (stress ratio) = (stress drop) / (normal stress) − dynamic frictional coefficient, the ration roughly indicates normalized stress drop. We found high stress ratio region seem to be overlapped the fault asperity. It suggests that the earthquake could have been created by a heterogeneous stress field generated from heterogeneous crustal structure.