Leif Wennerberg
L. Margheriti
Hsi-Ping Liu
Linda C. Seekins
1996
<div id="130404452" class="article-section-wrapper js-article-section js-content-section " data-section-parent-id="0"><p>We compare microtremor data to weak-motion<span> </span><i>S</i>-wave and coda recordings at sites in San Francisco in order to clarify the range of applicability of microtremor data to ground-motion prediction. We also compare<span> </span><i>S</i>-wave results to coda results. For each type of data, we compute spectral ratios of motions from two soil/rock station pairs and from an uphole/downhole pair in the Marina district. We compute horizontal/vertical ratios (Nakamura's method) at a soil site, a rock site, and the surface and borehole instruments. In the station-pair analyses, microtremor data show amplifications at the same fundamental frequency as<span> </span><i>S</i><span> </span>waves, but the frequencies of other peaks do not agree. The amplification at frequencies higher than 2 Hz is greater in the microtremor data. Station-pair ratios of coda data generally show spectral peaks occurring at the same frequencies, but with levels varying from one to four times the amplification from<span> </span><i>S</i>-wave ratios. Nakamura's method of analyzing microtremors agrees better with<span> </span><i>S</i>-wave station-pair results than the microtremor station-pair method over a limited frequency band that varies from station to station.</p></div>
application/pdf
10.1785/BSSA0860030627
en
Seismological Society of America
Site amplification at five locations in San Francisco, California: A comparison of S waves, codas, and microtremors
article