Source fault structure of the 2003 Bam earthquake in Iran,inferred from the Magnetotelluric and Aeromagnetic studies

摘要

Early in the morning on 26 December 2003 the ancient city of Bam in the south east of Iran,well known in the world for its historic citadel Arg-e-Bam,was shaken by a destuctive,Mw 6.6 earthquake. Even in the long and terrible earthquake history of Iran,where events of this nature are not rare,this one was especially desguctive This earthquake Surface displacement pattern revealed that slip occurred along an Lmknown fault. Surface geology of the region suggests thick aquifer that covers all the area To detect the subsurface geological features such as any hidden fault that caused the earthquake, the aeromagnetic and magnetotelluric methods might be very useful Aeromagnetic maps suggest a trend ofNW-SE for magnetic lineaments in the area One of them is a fault in Bam fault zone To study the Bam'S fault zone,MT data haye been collected on an east-west profile approximately perpendicular to the local strike of the faults 2D inversion and interpretation along this profile showed a zone with low resistivity at the depth of 2-8 Km that obviously ruptured Down there is a zone with lower resistivity hasn't been fractured yet This zone is consistent with the depth of aftershocks Near surface low anomalies refer to aquifer surrounding the fault branches