Evaluation of generic reference rock site conditions for Israel

Reference rock site conditions have a major role in site response analysis and therefore should be selected carefully. For the case of standard engineering applications, site response of soft soil sites is frequently evaluated with respect to a generic reference rock, which is commonly defined as part of the building standard. Amendment Five of the Israeli Standard for Design Provisions for Earthquake Resistance of Structures (SI-413) uses the National Earthquake Hazards Reduction Program (NEHRP) site classification for different types of soils, defining the reference rock site as a site with average shear-wave velocity of the upper 30 m (V _S30) of 760 m=s. NEHRP classification is based on comprehensive studies conducted in the western United States, showing relatively good correlation to site response for that region but was never modified to fit Israeli local conditions. A new generic reference rock profile for Israel was assembled by compiling 43 local velocity profiles identified as rock profiles by their surface lithology, combined with an additional 141 deep velocity profiles that penetrate to depths of approximately 4 km. Following the formation of the generic rock profile, a continuous function representing the reference rock conditions for future seismic engineering applications in Israel was constructed. In addition, the amplification associated with the reference rock profile was calculated using multiple approaches.