長大な逆断層による内陸地震の断層モデルのパラメータの設定方法の提案

Abstract

We proposed a new procedure for evaluating the parameters of the asperity models for predicting strong ground motions from inland earthquakes caused by long reverse faults. The evaluation formula of averaged dynamic stress drops obtained by Irie et al. (2013)1) for surface ruptured faults 15 to 300 km long was adopted in our procedure, because the evaluation formula of the averaged static stress drops for circular cracks, commonly adopted in existing procedures, could not be applied to surface ruptured faults or long faults. The averaged dynamic stress drop was estimated to be 24 bars from the data of the ruptured areas and the seismic moments of actual earthquakes, and the dynamic stress drop on the asperities was estimated to be 187 bars from the data of the short-period levels and the seismic moments of actual earthquakes. These results led that the asperity areas were 11 % of the entire ruptured areas.