ESTIMATION OF STRONG GROUND MOTION DURING THE ۱۹۹۷ KHORASAN EARTHQUAKE IN IRAN

An earthquake with magnitude ۷,۱ occurred in Khorasan Province, northeast Iran, on May ۱۹۹۷. The survey mission from Japan conducted a field investigation in Iran for two weeks from June ۱۶ to ۳۰. In this study, we estimated peak ground accelerations by using the results of fault survey, and to analyze wave motion in irregular ground and examine through the analysis the subsurface ground motion properties of ground. The village of Ardakul suffered much damage, and the maximum acceleration was estimated to be ۴۰۰ gal. Ground investigation were performed by S waves using a portable elastic wave exploration instrument at three villages in the damaged area. The ground was generally bard and its surface ground was such that the S wave velocity was about ۲۰۰ to ۴۰۰ rnisec