The Comparison of Earthquake Rupture Processes along Sumatra-Andaman Subduction Zone Revealed by CNDSN

Following the occurrence of September 12, 2007 earthquake, more and more seismologists keep eye on the Sumatra-Andaman subduction zone because a sequence of great earthquakes in this particular region have occurred during the past four years. Back-projection method by Ishii et al. (2005) is very successful in imaging the progression of the transient rupture front of the 2004 great Sumatra earthquake. This paper we present our results based on the newly built China National Digital Seismic Network (CNDSN) by using the Back-projection method. CNDSN consists of 48 real-time transmission broadband seismic stations at 500-600 km spacing. Despite of being sparse, it can play an equivalently important role as other dense regional networks (e.g., Hi-Net in Japan and GRSN in Germany) in deciphering earthquake rupture processes with a specifically designed imaging condition. Our results showed that: (1) those earthquakes had extra long duration of P wave indicating long rupture length; (2) among all the source parameters, the moment magnitude or its equivalent, seismic moment, source mechanism, focal depth as well as the earthquake rupture process, the last one plays a key role in the tsunami generation process. We carried out a comparison study on the characteristics of the rupture process of the tsunamigenic earthquakes occurred from 2004 to 2007. This research fits for the urgent need of studies on the rupture process for prevention and mitigation of tsunami disaster.