Estimation on site-amplification from different methods using strong motion data obtained in Tangshan, China

Introduction It has been known that each soil type responds differently when it is subjected to ground mo-tion from earthquakes. So, the study of local site effects on seismic ground motions is one of the most important goals of earthquake engineering. It is practical importance to develop methods for assessing the nature and potential of sediment amplification, especially when choosing the location and design of critical and essential facilities. At present, however, the method by which site …

Estimation on site-amplification from different methods using strong motion data obtained in Tangshan, China

A seismic observation array for strong motions was deployed to estimate seismic source, propagation path and local site effects in Tangshan, China. We compared site response from the S-wave inversion and those from other tech-niques, such as traditional direct spectral ratios of S waves and receiver-function of S waves. From the inversion, we found that S-wave quality factor, i.e. QS-value, is approximately satisfied with the relation of QS=67f 1.1 in the range of frequency from 0.5 Hz to 32 Hz and that the source spectra follow the w-2 model of seismic source for low fre-quencies less than about 12 Hz. From the comparison of site responses estimated by the different methods for each soil site, we found that all the methods can extract the same predominant peaks from the responses, the amplifications from direct S-wave spectral ratios are well correlated with those from the S-wave inversion within a factor of 2 to 3, while the correlation between the amplifications from S-wave receiver-function and those from the S-wave inversion is not good, especially for high frequencies more than 8 Hz.