断層モデルに基づく地震動応答スペクトル予測法と予測結果のばらつきに関する検討

Abstract

It is important to investigate the effect of the uncertainty of the condition of a fault model to the results of the ground motion prediction for scenario earthquake. In such investigation, many case studies of the ground motion prediction are required. In order to calculate the ground motions efficiently, we proposed the simple evaluation method of seismic response spectrum using a fault model. The proposed method using the simplification which assumed the random vibration can obtain easier the mean response spectrum than the calculation of a large number sample by the statistical Green's function method. Then, the effect of the uncertainty of the fault parameters to the result of the ground motion prediction for the scenario earthquake was investigated by the simulation based on many samples of fault model using the proposed method. Although the spatial distribution of the mean response spectrum was simple, the standard deviation of response spectrum showed complex spatial distribution. The standard deviation of response spectrum was large near a fault edge and at the points on the extension of a fault strike. Since the variability of the predicted response spectrum changes with locations of a calculation point, when evaluating the seismic hazard in consideration of the uncertainty of the fault parameters for the scenario earthquake, it is necessary to scrutinize the effect of the uncertainty for every target calculation point.