Comparisons of Shear-Wave Slowness in the Santa Clara Valley, California, Using Blind Interpretations of Data from Invasive and Noninvasive Methods

Abstract

Many groups contributed to a blind interpretation exercise for the deter- mination of shear-wave slowness beneath the Santa Clara Valley. The methods in- cluded invasive methods in deep boreholes as well as noninvasive methods using active and passive sources, at six sites within the valley (with most investigations being conducted at a pair of closely spaced sites near the center of the valley). Although significant variability exists between the models, the slownesses from the various methods are similar enough that linear site amplifications estimated in several ways are generally within 20% of one another. The methods were able to de- rive slownesses that increase systematically with distance from the valley edge, cor- responding to a tendency for the sites to be underlain by finer-grained materials away from the valley edge. This variation is in agreement with measurements made in the boreholes at the sites.