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Deep Shear Wave Velocity Measurements in the Las Vegas Basin

Principal Investigator: Barbara Luke, University of Nevada Las Vegas

This project will utilize the NEES "Liquidator" seismic vibrator and associated data acquisition equipment in Las Vegas during November 4-9, 2008, as it is transported to another project in Southern California (Jacobo Bielak, PI). It will be used in a surface wave testing campaign, to complement an existing project to characterize seismic response of the Las Vegas Valley. The equipment will be used to fill a vital data gap between shallow depths that are accessible with existing UNLV test equipment, and great depths that have been imaged through seismic refraction/reflection using explosive testing and group-wave velocity measurements from teleseisms. The overall purpose of the data collection campaign is to map shear wave velocities (VS) to support earthquake site response analyses. An auxiliary benefit of the testing is the opportunity to work with the trained experts that operate the NSF equipment and the instrumentation that accompanies it, to learn best practices for operation of our own small scale "minivib" vibroseis.

We perform SASW-style surface wave testing with the Liquidator. We plan to use NEES' data acquisition equipment in combination with our own. We intend to test at up to five sites in the Las Vegas Valley and Pahrump. Criteria for test sites include: (1) co-location with deep datasets already collected, thereby filling a continuous profile from surface to kilometer(s) deep; (2) co-location with measurements already made or planned using UNLV's minivib, to validate test processes and outcomes and to extend the VS profile to greater depth; (3) co-location with previous passive-source seismic measurements, to assess relative quality and depth capabilities, and (4) co-location with lithologic datasets.