Expected ground shaking intensities from a magnitude 7 earthquake on the Monte Vista-Shannon and Santa Clara thrust faults, Santa Clara Valley, Santa Clara County, California
Campbell Kenneth, W.; Thenhaus Paul, C.; Sangines Eugenia, M.; Seligson Hope, A.
Book - Pacific Section, Society of Economic Paleontologists and Mineralogists 76: 161-172
1995
Accession: 018888279
Recent earthquakes in thrust fault zones are focusing attention on active thrust belts as posing potential seismic risk in the San Francisco Bay Area. An estimate of peak ground accelerations and Modified Mercalli Intensities expected to occur within Santa Clara Valley, Santa Clara County, California, from an hypothesized magnitude 7 earthquake on the Monte Vista-Shannon thrust fault is presented. We find that the strong ground shaking throughout the valley from such as event is expected to result in peak accelerations in excess of 0.5g with values possibly as high as 1g, and Modified Mercalli intensities in excess of IX with values possibly as high X to XI. These estimates of ground shaking are generally as high or higher than those expected from large-magnitude earthquakes on the Hayward and San Andreas faults. Furthermore, the occurrence of these hypothesized earthquakes within the valley can be expected to result in surface rupture, liquefaction, landslides, and areas of extremely high ground shaking caused by the near source effects of source directivity (focusing) and radiation pattern. Based on the results of this study, we suggest that planners, regulators, and facility owners consider the safety and economic impacts of a major earthquake on one or more thrust faults within Santa Clara Valley in addition to those that can occur on the Hayward and San Andreas faults in their earthquake hazard mitigation strategies.