Seismological Aspects of the 2003 Bam, Iran, Earthquake and Its Aftershock Analysis

Abstract

The source mechanism derived from the inversion of long-period body waves revealed that the earthquake occurred on a north-south trending strike-slip fault with a thrust component. According to the source model estimated in this study, the 2003 Bam, Iran, earthquake was a multiple event formed by two subevents. The rupture following subevent one started at a depth of about 8 km. However, the depth of subevent two is about 10 km. The total seismic moment estimated from inversion processes is 8.34×1018Nm. The pulse duration of subevent one and subevent two was determined from source time function as 1.7 s and 0.8 s, respectively. Corner frequency and source radius have been calculated by using major pulse duration. The corner frequency and source radius are 0.187 Hz and 5.47 km, respectively. The aftershock events distributed along a 30 km north-south striking fault. The focal depths of aftershocks distribution show a nearly vertical alignment of aftershocks located between 6 and 20 km depth. The focal mechanism solutions of aftershocks indicate right-lateral strike-slip faulting on a north-south trending fault, parallel to the previously known Bam fault trace in the east of Bam.