BAM, IRAN EARTHQUAKE OF 26 DECEMBER 2003, MW6.5: A STUDYON THE STRONG GROUND MOTIONS

摘要

The Bam earthquake of 26 December 2003 (Mw6.5) occurred at 01:56:56 (GMT, 05:26:56 local time)around the city of Bam in the southeast of Iran. The Bam earthquake of 26/12/2003 (Mw6.5) hasdemolished the city of Bam, having a population of about 100000 at the time of the earthquake. The Bamfault - which was mapped before the event on the geological maps - has been reactivated during the26/12/2003 earthquake. It seems that a length of about 10km (at the surface) of this fault has beenreactivated, where it passed exactly from the east of the city of Bam. The fault has a slop towards the westand the foci of the event was located closed to the residential area (almost beneath the city of Bam). Thiscaused a great damage in the macroseismic epicentral zone; however the strong motions have beenattenuated very rapidly, specially towards the east-and west (fault normal) direction. The verticaldirectivity effects caused the amplification of the low frequency motions in the fault-normal direction aswell as the greater amplitude of the motion on the vertical direction.