HR: 1340h
AN: S43C-1025    [Abstracts]
TI: Geophysical Investigation of the California Wash Fault, Nevada
AU: * Salda\~{n}a, S C
EM: ssaldana@physics.unlv.edu
AF: University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154 United States
AU: Snelson, C M
EM: csnelson@unlv.nevada.edu
AF: University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154 United States
AU: Taylor, W J
EM: wjt@unlv.nevada.edu
AF: University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154 United States
AU: Hirsch, A C
EM: GeoAAronH@hotmail.com
AF: University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154 United States
AB: The California Wash Fault, located in the central Basin and Range province, is a zone of steeply W-dipping normal faults with probable Holocene scarps capable of generating M 6-7 earthquakes (Bidgoli et al., 2003). The fault zone is located ~70 miles northeast of Las Vegas, a highly populated area. If an earthquake were to occur along this fault zone, there are implications for strong ground motions in the Las Vegas basin as well as small towns closer to the fault zone (Bidgoli et al., 2003). The seismic hazard is increased because the local fault-controlled basins, including the Las Vegas basin, contain significant amounts of sand and clay, which have been identified as having increased amplification with strong ground motion. This seismic amplification in basin sediments could potentially cause a great amount of damage to buildings and other structures in and around the Las Vegas metropolitan area (Bidgoli et al., 2003). To better understand the seismic hazards and the fault zone geometry, a seismic reflection survey was conducted during the summer of 2004 along a part of the California Wash fault zone previously mapped and logged to show evidence of Holocene paleoseismicity. The reflection survey maps a shallow portion of the subsurface and images two strands of the fault. Twenty-four seismic recorders were set out along a profile normal to the strike of the fault at four meter intervals and seismic waves were generated by a hammer source. A total survey area of 40 meters by 92 meters was acquired across the fault zone. Seismic Processing Workshop (SPW) was used to processes the reflection data. The interpretation of these data confirms (1) the location of the California Wash fault; (2) that the fault dips steeply, 75 degrees WNW; and (3) that the fault is listric at depth. The vertical displacement along the profiles is 5 m and is consistent with recent magnetic and geologic studies conducted at the same location. An additional step in the analyses of these data will be to determine a velocity model in the survey area and re-process the reflection data with better resolved velocity values. These data will then be integrated with the existing magnetic and geologic interpretations of the area to better understand and characterize the seismic hazard.
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2004 AGU Fall Meeting