Temporal Seismic Observation and Preliminary Hypocenter Determination of Aftershocks of the 2003 Bam Earthquake, Southeastern Iran

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We investigate the hypocenter distribution of aftershocks of the 26 December, 2002 Bam earthquake Mw 0.5 using a temporal seismic network installed for 1 month from 6 February, 2004. Preliminary hypocenters were determined using automatic phase-picking and calculating software. The epicenters are distributed linearly about 20km in length parallel 3.5km west of the Bam fault, and extend from the south of Bam city to the heavily damaged area of eastern Bam city including Arg-e-Bam. The hypocenters are distributed vertically or slightly leaning toward the east in the depth range from 0km to 15 km. Using the hypocenter distribution we propose a schematic 3-D structure model of the source fault distinguished from the Bam fault. Eastern Bam city is located just above the northern part of the source fault and also on the rupture propagation direction from the asperity. It may be a major reason why eastern Bam city suffered the heaviest damage.