北海道大学地球物理学研究報告 = Geophysical bulletin of Hokkaido University;第73号

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強震動予測のためのスラブ内地震の特性化震源モデルの構築

岩田, 知孝;浅野, 公之

Permalink : http://hdl.handle.net/2115/44464
JaLCDOI : 10.14943/gbhu.73.129

Abstract

We study characterized source model for the strong motion prediction of intraslab earthquakes in the same manner as crustal earthquakes (Somerville et al., 1999) and interplate earthquakes (Murotani et al., 2009). We characterized the heterogeneous slip distributions of 11 events with MW 6.6-8.3 and determined rupture area(S), total asperity area(Sa), and average slip(D)with following the procedure proposed by Somerville et al.(1999). Assuming power of 2/3 dependency of S and Sa on seismic moment and that of 1/3 for D, we got the empirical relationships as follows, S(km2 )= 6.57×10-11×M0 2/3(Nm) Sa(km2 )= 1.04×10-11×M0 2/3(Nm) D(cm)= 2.25×10-5×M0 2/3(Nm) The stress parameters on and off asperities are estimated as 28.9 MPa and 4.6 MPa, respectively, from the asperity model by Boatwright(1988). We also summarized size and position of strong motion generation area(SMGA, Miyake et al., 2003)for intraslab earthquakes by broad-band ground motion simulations. We found SMGA corresponds to the asperity and the size of SMGA is equivalent to or a little bit smaller than the asperity size. Based on these characteristics, we propose the characterized source model of intraslab earthquakes for strong ground motion prediction. We confirmed the procedure by simulating strong ground motions for the 2001 Geiyo earthquake(MW 6.8, hypocentral depth=46 km). Using these empirical relationships, we constructed the characterized source models for the 2001 Geiyo earthquake and simulated ground motions at strong motion observation sites using the empirical Green's function method.

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