The Bam (Iran) Earthquake of December 26, 2003: From an engineering and seismological point of view

This paper is devoted to studying the destructive Bam earthquake from an engineering seismological point of view. On December 26, 2003 a large earthquake of magnitude 6.7 (Ms) shook the Bam district located in southeastern Iran. About 80% of buildings totally collapsed. Several dozen villages were destroyed and tens of them were severely damaged. More than 45,000 people were killed, and 30,000 were injured. According to the macroseismic data, focal depth of the event was estimated at 7±2 km. The event was associated with a 9 km surface rupture of the Bam fault. The maximum residual strike-slip displacement is 5 cm, which is left-lateral. The highest recorded peak ground acceleration is at Bam station (0.98 g vertical and 0.87 g horizontal), located about 1.5 km from the surface rupture. The macroseismic analyses show that the epicenter of the quake is 1.5 km east of Bam. All of the masonry buildings totally collapsed in the epicentral area. Many semi-engineered structures were heavily damaged and some of them collapsed. Engineered structures, constructed according to the seismic code of Iran, have shown very good structural behavior without significant damage. Finally, the earthquake intensity at the epicenter is determined as IX+ on the MSK scale, which strongly decreases with distance from the surface ruptures.