ANALYSIS OF SEISMIC INTENSITIES OBSERVED IN ISRAEL

Macroseismic data of earthquakes felt in Israel and also recorded inst rumentally are analyzed. The analysis yields the following empirical r elations: I = 0.2 + 1.6M - 2.5 log(r) - 0.003r, sigma = 0.7, r(2) = R( 2) + 15(2), M = 2.5 + 0.5I(E), sigma = 0.3, I-E = 1.6M - 3.5, sigma = 0.5, M = 0.3 + 2.1 log D, sigma = 0.4, where M is the local magnitude, I is the expected seismic intensity (MSK-scale), R is the epicentral distance, I-E is the average seismic intensity in the focal area (with in 20 km), and D is the radius of the area in which seismic intensitie s of grade III or more were observed. sigma is the one standard deviat ion. Using macroseismic observations in Israel following distant-earth quakes and by using the empirical attenuation function (see above), an attempt is made to identify areas within Israel with unusual response . The results indicate a poor correlation between the intensity respon se of a site and its geological and geotechnical properties.