Trade-offs of Dynamic Parameters Inferred from 2D Dynamic Source Inversion Results

Dynamic rupture simulations have been performed in order to generate a physically consistent slip distribution. An attempt has been made to investigate the governing parameters of these simulations, called dynamic parameters, during historical earthquakes. However, it has been reported that the parameters are not estimated accurately when employing only the ground motion records because of trade-offs existing within the parameters. In this study, we apply a dynamic source inversion to 2D synthetic tests in order to discuss parameter trade-offs. The results of the sensitivity tests, which consist of numerous sets of inversions including a fixed stage and a released stage, imply trade-offs between the rupture parameter and the other parameters. From a detailed comparisons of the slip rates and the waveforms, it is seen that the growing between the rupture time and the peak time do not contribute well to the generated waveforms. From a simple 1D assumption, a weakening gradient is analytically related to the peak to rupture time with a -1 slope in the log-log plot. The estimated values from the synthetic tests almost mirror the values of the -1 slope.