Seismic hazard in the San Fernando basin, Los Angeles, California: A site effects study using weak-motion and strong-motion data

Jamison H. Steidl, Luis F. Bonilla, & Alexei G. Tumarkin

Published 1995, SCEC Contribution #260

During the months that followed the 17 January 1994 M6.7 Northridge, California earthquake, portable digital seismic stations were deployed in the San Fernando, Los Angeles metropolitan region to recover aftershock data. One of the goals of this deployment was to examine the seismic hazard in this urban environment by way of site-specific amplification factors. We calculate amplification at 17 sites using a variety of the “standard” techniques and compare the results. We compare site response estimates which use the two horizontal components of ground motion as a complex signal with estimates which use only a single component or the geometrical mean of the site response estimate from each component. We compare whole record estimates of the site response with estimates which window the s-wave and coda-wave portions of the data. We also compare horizontal coda-wave with vertical coda-wave site response estimates. We find that the vertical coda-wave site response estimates tend to give larger amplification factors than horizontal coda-wave estimates. We also find that the vertical and horizontal coda-wave estimates produce larger amplification factors by 2.0 and 1.6 respectively when compared to the horizontal s-wave estimates.

Citation
Steidl, J. H., Bonilla, L. F., & Tumarkin, A. G. (1995). Seismic hazard in the San Fernando basin, Los Angeles, California: A site effects study using weak-motion and strong-motion data. Poster Presentation at Fifth International Conference on Seismic Zonation.