Broadband Ground Motion Simulations of Mega-Thrust Subduction Earthquakes Based on Multi-Scale Heterogeneous-Source Model


Abstract eng:
Six segments for the region off the coast of Tohoku from Middle Sanriku-Oki to Ibaragi-Oki were indicated with seismic activities of past 400 years by the Headquarter of Earthquake Research Promotion, Japan (HERP) before the 2011 Mw 9 Tohoku earthquake. Long-term forecasts for individual segments in this region were done so that Mw 7–8.4 earthquakes would occur within those segments, having different recurrence times from one to the other. The information about the source process and ground motions of this earthquake was obtained by dense networks of geophysical instruments including strong-motion, teleseismic, tsunami, and geodetic sensors. Most of slip distribution inverted from long-period records such as geodetic and tsunami data are placed at depths shallower than the hypocenter toward the trench. On the other hand, shortperiod seismic energy obtained by the back-projection method was generated mainly from the down-dip areas near the coasts of Pacific coast. We also estimate a short-period source model for generating strong ground motions from this earthquake by comparing the observed records from the mainshock with synthetic motions based on an asperity source model and the empirical Green’s function method. We find the segmentation controls the characteristics of ground motions from the rupture process inversion of near-field strong motion records as well as earthquake occurrence in the source region of this event. The period-dependent source behavior of this earthquake can be interpreted by a multi-scale heterogeneous earthquake model. Recent other Mw 9.0 class subduction earthquakes such as the 2004 Mw 9.1 Sumatra earthquake and the 2010 Mw 8.8 Maule earthquake are known to have almost the same period-dependent source model mentioned above. Then, we propose an improved idea for recipe of predicting strong ground motions for mega-thrust subduction earthquakes based on the multi-scale heterogeneous-source model.

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Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
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 Record created 2017-01-18, last modified 2017-01-18


Original version of the author's contribution as presented on USB, paper 3019.:
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