Destructive strong motion estimation during the old inland large earthquakes based on empirical heterogeneous source model

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Most of the uncertainties in predicting strong ground motion is to model source heterogeneities of future earthquakes. An available method we propose for characterizing the heterogeneous slip distribution on the fault plane is based on the empirical source characterization derived from the slip models of the crustal earthquakes by Somerville et al. (1999). Areas of asperities having large slips are defined based on the slip models derived from waveform inversion of longer ground motion recordings than 1 second. Using this method, we can specify asperities with uniform slip on the fault surface whose sizes are constrained by the entire seismic moment of an earthquake. We need to investigate the effectiveness of the asperity models through the simulations of broad-band strong ground motions. In this study, the validity and applicability of the source models composed of some asperities and background (off asperities) for strong ground prediction are examined through the simulation of strong ground motions during the 1945 Mikawa earthquake and the 2000 Tottori-ken Senbu earthquake in Japan.In the simulation of the Mikawa earthquake, we have obtained that the distributions of the synthetic peak velocity and instrumental seismic intensity roughly correspond to the distribution of the seismic intensity estimated from the observed collapse ratio of wooden houses. Furthermore, the peak velocity of the corresponding synthetic waveform is close to 150 cm/sec, and compatible to the 1995 Hyogo-ken Nanbu earthquake and the 1948 Fukui earthquake.Resultantly, we found that the asperity models are available for estimating broad-band strong ground motions, and that the destructive strong motions in the area of the intensity 7 have velocity amplitude larger than 150 cm/sec.