On 26 December 2003, a destructive earthquake occurred in southeastern Iran, devastating the city of Bam and causing serious damage to the nearby villages. The death toll has been estimated to exceed 30,000. The highest intensity of shaking (VIII-IX) was observed at Barn city, where more than 90 percent of the buildings were demolished. The source of this shock was reported to have had right-lateral strike-slip mechanism faulting in the north-south direction. The earthquake was recorded on a regional network consisting of 50 strong-motion stations (SSA-2 Accelerographs), of which 30 were located within 1-300 km from the epicenter. The recorded peak ground accelerations range from 0.9 to 0.01 g. At the Bam station, the nearest station to the source, the short SP time of 0.9 sec clearly indicates that the source of this earthquake initiated underneath the city. Vertical and horizontal peak accelerations recorded at Bam are both about 0.9 g. The horizontal motions at this station are simple and have impulsive shape with a relatively short duration of less than 8 seconds of strong shaking. The motions in the east-west direction, perpendicular to the fault, are significantly larger than those in the north-south direction. It appears that the passage of the rupture front near the city was the main cause of such a strong shaking. A preliminary analysis of the strong-motion data indicates that a single and none-multiple source area probably characterizes this earthquake. The ML magnitude calculated from 46 horizontal components is 6.7. Spectral analysis of P and S waves recorded by the regional broadband stations gives Mw 6.7. Comparing the recorded peak horizontal accelerations with the attenuation relations derived for the eastern Iran, we estimate Ms 6.8. The earthquake was proceeded by a foreshock and was followed by as many as 50 aftershocks, most of which are confined in a short distance from Bam.

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