Evaluation of Generalized Site Response Functions for Typical Soil Classes (B,C,and D) in Taiwan

Abstract

Empirical amplification functions for site classes B, C, and D in Taiwan were evaluated as the ratio between Fourier amplitude spectra of recorded accelerograms and spectra modeled for a hypothetical very hard rock (VHR) site. The approach allowed testing applicability of various spectral models in the studied region. More than 1,000 acceleration records obtained during 21 intermediate-sized and large earthquakes (M_L>5.5), including the M_L 7.3 (M_W 7.6) Chi-Chi earthquake (21 September 1999) and the large aftershocks (M_L 6.8), were used. The evaluated amplification functions were compared with independent data, which were obtained recently for Taiwan, the western United States, and Greece. The prominent influence of geologic and geomorphologic factors on site amplification functions for the considered cases of rock (Class B), soft rock or very dense soil (Class C), and stiff soil (Class D) sites has been observed for the Taiwan region.