Soil site response Original Research Article

The response of stiff quaternary soil sites to strong earthquake shaking is an important factor in the development of seismic siting criteria for nuclear power plants. Analytical methods for estimating this site response are in common use, but there is need for empirical verification of these modeling techniques. There are two dense 3-D strong motion arrays installed and operating in California to directly measure the response of stiff quaternary soil to earthquake shaking. These are the Hollister Earthquake Observatory and the Borrego Valley Downhole Arrays. Site response measurements from these arrays, along with detailed geotechnical and geophysical site investigations, will provide important calibration and confirmation of site response modeling techniques used for seismic siting criteria development. This paper presents an overview of the two arrays and initial results of the measurements.