Dependence of strong ground motion on magnitude-distance, site geology and macroseismic intensity for shallow earthquakes in Greece: I, Peak horizontal acceleration, velocity and displacement

Abstract

Strong motion data were used to study attenuation characteristics of horizontal peak acceleration, velocity and displacement. The data base consists of 105 horizontal components from 36 shallow earthquakes in Greece of magnitude 4·5 to 7·0, and of 16 horizontal components from four shallow subduction earthquakes in Japan and Alaska of magnitudes 7·2 to 7·5. The resulting equations are: ln a g = 3·88 + 1·12 Ms − 1·65 ln ( R + 15) + 0·41 S + 0·71 P ln v g = −0·79 + 1·41 Ms − 1·62 ln ( R + 10) − 0·22 S + 0·80 P ln d g = −5·92 + 2·08 Ms − 1·85 ln ( R + 5) −0·97 S + 1·23 P where a g is the peak horizontal acceleration in cm/sec 2, v g the peak horizontal velocity in cm/sec, d g the peak horizontal displacement in cm, Ms the surface wave magnitude, R the epicentral distance in km, S is equal to zero at ‘alluvium’ sites and equal to one at ‘rock’ sites, and P is equal to zero for 50 percentile values and equal to one for 84 percentile values. Furthermore, utilizing only the Greek data for which modified Mercalli intensities, I MM, were available around the recording stations, the following empirical relations are derived: ln a g = 0·28 + 0·67 I MM + 0·42 S + 0·59 P ln v g = −3·02 + 0·79 I MM − 0·04 S + 0·70 P ln d g = −5·82 + 0·96 I MM −0·49 S + 1·24 P The relations proposed here are compared with corresponding empirical relations derived previously for western United States, Japan and southern Europe.