ABSTRACT:

The moment tensors of large and intermediate earthquakes are routinely constrained by multiple agencies using long-period seismic signals. However, these conventional analyses simplify the rupture process of an earthquake as single point source, which might not be appropriate if the earthquake has a fault dimension comparably larger than the signal’s dominant wavelength or includes multiple subevents occurring on a multi-fault system. Such source complexity in terms of irregularity in the rupture propagation and in the distribution of moment release can adequately yield distinct seismic waves, and therefore might be deciphered through more carefully waveform modeling.

Here we develop a nonlinear Multiple Double Couple (MDC) inverse algorithm in the hope of resolving such complex rupture process.  This approach has been widely testified using long-period signals, teleseismic body waves and local broadband strong-motion records. As will shown in our study, we have successfully reproduced the earthquake fault geometry using multiple point source approximation. Such point source approximation provides more precise priori information for the subsequent finite fault inversion and assists us to detect possible dynamic triggering seismic event. The development of high-quality digital seismograph network and advances in parallel computational capability enable us to perform this quick and precise MDC and finite fault inversion, which therefore would play an essential role in the real-time earthquake hazard analysis.