SHALLOW SHEAR-WAVE STRUCTURE AND ITS EFFECTS ON BUILDING DAMAGE AT STRONG MOTION STATIONS IN TAIWAN BASED ON MICROTREMOR MEASUREMENTS

In order to examine the local site effects on the strong motion records of the 1999 Chi-Chi earthquake in Taiwan, microtremor measurements are conducted using arrays of sensors at 11 strong motion stations. Shallow shear wave velocity profiles of these stations are estimated based on an inverse analysis of both microtremor dispersion characteristics and H/V spectra. Equivalent linear analysis is conducted using the estimated Vs profiles. It is shown that local soil conditions including nonlinear soil behavior might have had significant effects on the ground motion and performance of buildings during the earthquake.