HR: 0830h
AN: S11D-0323    [PDF]
TI: Initial Results From the Las Vegas Valley Broadband Array Based on Differential Travel Time Residuals and Interstation Phase Velocities
AU: * McEwan, D J
EM: mcewand@unlv.nevada.edu
AF: Department of Geoscience, University of Nevada Las Vegas, 4505 Maryland Parkway, 4010, Las Vegas, NV 89154-4010 United States
AU: Snelson, C M
EM: csnelson@unlv.nevada.edu
AF: Department of Geoscience, University of Nevada Las Vegas, 4505 Maryland Parkway, 4010, Las Vegas, NV 89154-4010 United States
AU: Tkalcic, H
EM: tkalcic1@llnl.gov
AF: Lawerence Livermore National Laboratory, P.O. Box 808, L-206, 800 East Avenue, Livermore, CA 94551 United States
AU: Rodgers, A
EM: rodgers7@llnl.gov
AF: Lawerence Livermore National Laboratory, P.O. Box 808, L-206, 800 East Avenue, Livermore, CA 94551 United States
AB: Eight broadband seismometers, collectively known as the Las Vegas Valley Broadband array (LVVBB), were deployed by Lawrence Livermore National Laboratory (LLNL) and the University of Nevada Las Vegas (UNLV) in September 2002. The LVVBB array recorded data continuously from local and regional earthquakes as well as global teleseisms through late January 2003. The coverage area extends throughout the northeastern regions of the Las Vegas Valley; the area estimated to be the deepest portion of the Las Vegas basin based on gravity data. Differential travel time residuals were calculated through the cross-correlation of P-wave arrivals from global teleseisims to better constrain basin geometry and depth to basement. The calculated delay times show variations up to 0.5 s over distances of 15 km or less. The residual pattern is consistent across the basin and is associated with zones of thicker basin fill. This supports earlier models of the basin. A number of regional earthquakes originating in southern California are linearly aligned with the LVVBB array. Interstation phase velocities of Rayleigh wave propagation from these events are being used to create surface wave dispersion curves to assist in modeling the shear wave velocity structure of the region. Given the current models, average shear velocities of 0.96 km/s and 1.25 km/s characterize the change from shallow to deep sediments. These new results will further constrain the shear wave velocity in the study area, and aid in evaluating the behavior of basin fill for building construction. These studies contribute to the modeling of ground-motions in Las Vegas Valley and can be used to assess the Valley's response in the event of an earthquake or future nuclear testing at the Nevada Test Site.
DE: 7200 SEISMOLOGY
DE: 7212 Earthquake ground motions and engineering
DE: 7223 Seismic hazard assessment and prediction
DE: 7255 Surface waves and free oscillations
DE: 9350 North America
SC: Seismology [S]
MN: 2003 Fall Meeting