THE 26 DECEMBER 2003 EARTHQUAKE IN IRAN

Abstract

An earthquake occurred on December 26th, 2003 at 01:56 UTC (05:26 local time), near the city of Bam in the southeastern part of Iran (2). The earthquake’s coordinates were 28.99N and 58.29E, 10 km southeast of Bam (4). From the earthquake’s effects on the surface, experts presumed the epicenter to be directly under the city of Bam. According to the first information available, 41,000 people lost their lives and more than 30,000 people were injured. In Bam, 85% of all the buildings were destroyed or heavily damaged. The strongest aftershock, with a magnitude of M=5.1, occurred on the same day at 03:06 UTC. The magnitude of the earthquake was 6.5; scientists used the S-P waves after the first shock to estimate the depth which was 8 km (2). The macroseismic intensity was estimated at Io=IX EMS (12-degree European macroseismic scale). The intensities rapidly decreased in a direction perpendicular to the fault (Figure 2). According to USGS data, this was estimated to be a sheer fault with only a slightly vertical movement. Nevertheless, measured shocks show distinctive movement along the vertical component. The peak ground accelerations (PGA) for the horizontal component and the vertical component were between 0.7 to 0.8 g and 1.01 gs respectively (1). Besides the great amount of damage, the earthquake also caused several natural phenomena: landslides, liquefaction and sinkholes in the earth. A crack appeared between Bam and Beravat.