by R.B. Darragh and A.F. Shakal
Darragh, R.B., and A.F. Shakal (1992). The Site Response of Two Rock and Soil Station Pairs to Strong and Weak Ground Motion. SMIP92
Seminar on Seismological and Engineering Implications of Recent Strong-Motion Data, p. 1-1 - 1-11.
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The site response to strong and weak ground motion depends largely on the subsurface conditions
at the soil site for the two rock-soil station pairs studied. The first station pair consists
of a soft-soil site and a sandstone/shale site (Treasure Island and Yerba Buena Island). For
strong motion, the soft-soil site is amplified by a factor of about 3 over the rock site from
0.5 to 2.0 Hz. The amplification is much higher for weak motion and suggests a dependence on
A second station pair near Gilroy consisting of a stiff-soil site and a sandstone site was
studied with contrasting results. Unlike the results for the soft-soil study above, the
estimated stiff-soil site response is not significantly different for strong and weak motion
from 0.5 to 2.0 Hz.