Moment Tensor Inversion of Some Events of Qeshm Island Earthquake Sequences Using INSN Broadband Data

Document Type : Technical Note




Regional moment tensor inversion of the mainshock and three aftershocks of earthquake series in and around Qeshm island in the Persian Gulf has been carried out using high quality broadband data from Iran National Seismic Network (INSN). The events which have been recorded at regional distances by stations of INSN have started to jolt the island and the mainland Iran in two sequences starting in November 2005 with a Mw=5.9 event and yet with another series of events in June 2006 with a Mw=5.8 earthquake. The results of the analysis for the main shock and three aftershocks from the two above mentioned earthquake series are presented. From the focal mechanism solutions, it appears that a mainly south-north trending compressional axis prevails. Apart from a major aftershock in the first earthquake series which shows the strike-slip mechanism with small normal component of slip, the main shock and the other two aftershocks show large component of reverse faulting along causative faults trending NEE-SWW to SE-NW. The horizontal components of main compressional axes deduced from obtained solutions suggest south-north directions which are in accordance with the expected axes of shortening.