Recorded Aftershocks by IIEES Strong Ground Motion Instruments

H. Hamzehloo & M. Zare
 

1.Recorded aftershocks by IIEES

One strong ground motion station is installed by International Institute of Earthquake Engineering after December 26, 2003 earthquake at Jahangardi Hotel close to citadel of Arg-e- Bam on shallow alluvium from January 3, 2004. Up to know this station have recorded 210 aftershock records. The maximum peak ground acceleration of 42 cm/sec2 was recorded for these 210 aftershocks at this station on January 3, 2004 (Fig.1).

Fig.1 Aftershocks recorded by IIEES.

2.Near field SH- wave analysis

The strong ground motion of the destructive December 26, 2003 Bam earthquake, which was recorded by Building and Housing Research Center, has been analysed to infer about the ruptur process and causative fault during this earthquake base on method given by Sarkar et.,al (2003). It is identified on these accelerograms the imprints of two asperities located on the main causative fault. The strike, dip and slip of these two subevents have been estimated using the SH spectral amplitude of near field data (Fig.2). The analysis shows that the rupture started from subevent S1 in the south of Bam and propagated  toward Bam to North. The maximum energy has been released by subevent S2, which is located below the Bam twon and caused widespread huge damage to Bam.

Fig.2 Location of two subevents and their fault plane solutions.
BHRC stations are shown by triangle.

Notice: The details of the analysis will be appeared in JSEE.