Strong-Motion Prediction by Semi-Empirical Method Based on Variable-Slip Rupture Model of Earthquake Fault

A variable-slip rupture model of a large-earthquake fault is taken into account in a semi-empirical method for predicting strong-ground motions. The source spectrum of the (p, q)-th sub-fault is represented by the omega-square model with two corner circular frequencies. The one is V_<pq>/D_<pq>, where V_<pq> is the maximum slip velocity and D_<pq> is the final slip, and the other is 2 β_<pq>λ_<pq>, where β_<pq> is the shear-wave velocity of the medium and λ_<pq> is the equivalent radius of the sub-fault. This new method is applied to the variable-slip rupture model of the 1923 Kanto earthquake obtained by Wald and Somerville (1995). The synthesized strong-ground accelerations are consistent with the seismic intensities reported by the Japan Meteorological Agency and with those estimated from the overturned tomb stones and the collapsed houses.