M.R.Ghayamghamian - International Institute of Earthquake Engineering and seismology,P.O.Box

The presence of 2D or 3D near-surface geological irregularities such as alluvial valleys or sedimentary basins may remarkably change the amplification characteristics at a site. The quantification of seismic sites effects on such irregularities can be challenging task in strong ground motion estimation, especially if numerical simulations are to be avoided for lack of sufficient detailed geological and geophysical data. An alternative approach to the identification of resonant response on sedimentary valleys and basin relies on utilizing empirical approach. In empirical approach, the spectral analysis of earthquake and microtremor data can be applied to identify the basic features of 2D response. To this end, the earthquake data recorded by IIEES seismic network is analyzed to investigate local 2D or 3D site effects in Bam city. the reference site technique is employed to identify frequency dependent site amplification characteristics in different sites. furthermore, the non-stationary spectrum is also calculated for main shock of Bam earthquake to investigate the possibility of appearance basin-induced surface wave or edge effect at the sites.

2D/3D site effects , non-stationary spectrum , basin-induced surface wave , edge effects , reference site technique