SEE6 / 1 / IIEES REGIONAL SITE EFFECT ZONATION OF QESHM ISLAND (IRAN) H. Gerivani 1 , E. Haghshenas 2 , R. Safaeian Amoly 3 , A. Shafiee 4 1 Ph.D. Student, Department of Engineering Geology, Ferdowsi University of Mashhad, Mashhad, Iran (h.grivani@iiees.ac.ir) 2,4 Assistant Professor, International Institute of Earthquake Engineering and Seismology, Tehran, Iran (hagshen@iiees.ac.ir ), (Shafieea@iiees.ac.ir) 3 M.Sc. Graduate, Geothecnic Research Center, IIEES, Tehran, Iran (r.s.amoly@iiees.ac.ir) ABSTRACT Regional site classification based on the criteria introduced by Borcherdt (1994), NEHRP (1994 - 2000), UBC (1997), IBC (2000, 2003) and Seed et al. (2001), with the aim of estimation of earthquake ground motion at the surface, have been done for the Qeshm Island located at Persian Gulf (south of Iran), as a part of an exhaustive study on earthquake hazard in this Island. Three steps including: site classification base on engineering geological map of Qeshm Island, determining amplification factor of each class of sites and preparing distribution map of peak ground acceleration (PGA) for return period of 475 year by overlapping peak bedrock acceleration (PRA) and site classification maps, were conducted. Furthermore, the data of a temporary seismological network (including 17 stations) and some single station microtrmor measurement were used as a verifying factor. The result, shown as a map of site classification and a PGA map, show the relative importance of the effect of local site conditions in seismic ground motion for whole part of the Island. Keywords: Zonation, Site Effect, Qeshm Island, Engineering Geology, Microtremore. 1. INTRODUCTION Ground shaking and its associated damage to engineered structures can be strongly influenced, not only by source and path effects, but also by surface and sub-surface geological and topographical conditions in the vicinity, known as “local site effects”. Evidence of this can be found in the 1990 Manjil–Rudbar and the 2003 Bam earthquakes, two major seismic events in Iran in the past two decades that resulted in a large number of casualties. Although these cities had comparatively low populations, the lack of suitable development and earthquake risk management led to high human and physical costs. These tragedies prompted the government to implement earthquake risk mitigation measures, including seismic hazard zonation and microzonation of vulnerable cities, to facilitate urban planning. ﺷﺸﻤﻴﻦ ﺑﻴﻦ ﻛﻨﻔﺮاﻧﺲ زﻟﺰﻟﻪ اﻟﻤﻠﻠﻲ زﻟﺰﻟﻪ ﻣﻬﻨﺪﺳﻲ و ﺷﻨﺎﺳﻲ 6 th International Conference on Seismology and Earthquake Engineering