Moment Magnitude Estimation of Large Earthquakes Based on Long-Period Ground Motion Prediction Equations and Preassumed Fault Models

We proposed a simple method of moment magnitude estimation based on long-period (5-30 s) ground motion prediction equations (GMPEs). We constructed empirical fault models for different trial magnitudes. The source-to-site distance from the preassumed fault models to seismic stations was estimated. The best magnitude estimate was determined with reference to the minimum residual between the magnitude estimated from the GMPEs and the trial magnitude used to define the fault model. Using this method, the moment magnitudes of six large interplate earthquakes that occurred around the Japan Islands were estimated. The estimated magnitudes obtained in this study are in good agreement with those calculated from the global centroid moment tensor project. The method has potential to be used for rapid moment magnitude estimation of large earthquakes.