HR: 1320h
AN: S43A-0979    [Abstracts]
TI: Seismic Wave Amplification in Las Vegas: Site Characterization Measurements and Response Models
AU: * Louie, J N
EM: louie@seismo.unr.edu
AF: Nevada Seismological Laboratory, University of Nevada, Reno, NV 89557 United States
AU: Anderson, J G
AF: Nevada Seismological Laboratory, University of Nevada, Reno, NV 89557 United States
AU: Luke, B
AF: Civil Engineering Department, University of Nevada, Las Vegas, NV 89154 United States
AU: Snelson, C
AF: Geoscience Department, University of Nevada, Las Vegas, NV 89154 United States
AU: Taylor, W
AF: Geoscience Department, University of Nevada, Las Vegas, NV 89154 United States
AU: Rodgers, A
AF: Energy and Environment Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94551 United States
AU: McCallen, D
AF: Energy and Environment Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94551 United States
AU: Tkalcic, H
AF: Energy and Environment Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94551 United States
AU: Wagoner, J
AF: Energy and Environment Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94551 United States
AB: As part of a multidisciplinary effort to understand seismic wave amplification in Las Vegas Valley, we conducted geotechnical and seismic refraction field studies, geologic and lithologic interpretation, and geophysical model building. Frequency-dependent amplifications (site response) and peak ground motions strongly correlate with site conditions as characterized by the models. The models include basin depths and velocities, which also correlate against ground motions. Preliminary geologic models were constructed from detailed geologic and fault mapping, logs of over 500 wells penetrating greater than 200 m depth, gravity-inversion results from the USGS, and USDA soil maps. Valley-wide refraction studies we conducted in 2002 and 2003 were inverted for constraints on basin geometry, and deep basin and basement P velocities with some 3-d control to depths of 5 km. Surface-wave studies during 2002-2004 characterized more than 75 sites within the Valley for shear velocity to depths exceeding 100 m, including all the legacy sites where nuclear-blast ground motions were recorded. The SASW and refraction-microtremor surface-surveying techniques proved to provide complementary, and coordinating Rayleigh dispersion-curve data at a dozen sites. Borehole geotechnical studies at a half-dozen sites confirmed the shear-velocity profiles that we derived from surface-wave studies. We then correlated all the geotechnical data against a detailed stratigraphic model, derived from drilling logs, to create a Valley-wide model for shallow site conditions. This well-log-based model predicts site measurements better than do models based solely on geologic or soil mapping.
UR: http://www.seismo.unr.edu/hazsurv
DE: 7219 Nuclear explosion seismology
DE: 7223 Seismic hazard assessment and prediction
DE: 7205 Continental crust (1242)
DE: 0905 Continental structures (8109, 8110)
DE: 0994 Instruments and techniques
SC: Seismology [S]
MN: 2004 AGU Fall Meeting