Automatic Inversions of Strong‐Motion Records for Finite‐Fault Models of Significant Earthquakes in and Around Japan

Abstract

AbstractAutomatic and rapid imaging of earthquake rupture process is a difficult task but critical for postearthquake response and possible tsunami early warning. We have developed an automatic system for finite‐fault inversion based on the iterative deconvolution and stacking (IDS) approach, in which we screen the waveforms and update the fault size automatically. Strong‐motion seismograms are used in offline tests to invert for the rupture processes of 34 significant earthquakes in 2008–2017 in and around Japan with magnitudes MW ≥ 6.0 occurred onshore and MW ≥ 6.5 offshore. Rupture model of an earthquake, including moment magnitude, source time function, slip distribution, rupture velocity, and stress drop, is obtained in ~1.5 min on a desktop PC. The moment magnitudes we obtained are consistent with those published by other agencies. The slip distributions, rupture directions, and velocities also agree well with those released by the Japan Meteorological Agency. In all test cases, our results show that the automatic inversion of strong‐motion data can provide reliable major source parameters without manual revision, which demonstrates great potential for emergency response and tsunami early warning purposes. The automatic inversion system developed in this work can also be used to build catalogs of finite‐fault models for moderate to strong earthquakes in other areas where the moment tensor solutions and near‐field waveform data are available.