HR: 0800h
AN: T51D-1383    [Abstracts]
TI: Pliocene - Quaternary Faults and Potential Seismic Hazards in Southern Nevada
AU: * Taylor, W J
EM: wjt@unlv.nevada.edu
AF: Deprtment of Geoscience, University of Nevada, 4505 Maryland Parkway, Las Vegas, NV 89154-4010 United States
AU: Wagoner, J
EM: wagoner1@llnl.gov
AF: Lawrence Livermore National Laboratory, Earth Science Division, P.O. Box 808 L-221, Livermore, CA 94551 United States
AU: dePolo, C M
EM: cdepolo@unr.edu
AF: Nevada Bureau of Mines and Geology, University of Nevada, Reno, Reno, NV 89557 United States
AU: Luke, B
EM: bluke@egr.unlv.edu
AF: Department of Civil & Environmental Engineering, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154-4015
AU: Louie, J
EM: johnlouie@paradise.net.nz
AF: Nevada Seismological Laboratory and Department of Geological Sciences, Mail Stop 174, University of Nevada, Reno, Reno, NV 89557 United States
AB: Known Quaternary faults in the Central Basin & Range Province (CBR) have a southern limit at about 35 degrees 30' N latitude, south of Las Vegas, NV. The boundary is generally aligned with the southern end of the Sierra Nevada and strike-slip faults, such as those in Death Valley, that accommodate the right-lateral motion transferred from the plate boundary to east of the Sierra Nevada. Between ~8-4 Ma, the time range when the right-lateral motion was transferred to the east, CBR tectonism changed from rapid extension, low-angle normal faulting, and strike-slip faulting in the center to strike-slip faulting in the west and slower extension along normal faults in the middle and eastern CBR. Timing data from known <6-4 Ma CBR normal faults near the southern limit of Quaternary faulting show synchronicity with strike-slip faults in the southern Walker Lane and Eastern California shear zone on the west. Excellent examples of young faults in southern Nevada lie in Las Vegas basin and eastward to Mesquite. Our detailed stratigraphic and fault model of Las Vegas basin combined with shear-wave data shows significant ground shaking would occur there as a result of large magnitude earthquakes on almost any CBR fault. Faults in southern Nevada with documented Holocene activity include the normal-slip California Wash and Black Hills faults, and the strike-slip Mead Slope, Rock Valley, Pahrump Valley and Amargosa Valley faults / fault zones. The latter two faults aid in accommodating the step-over of some plate boundary slip from the San Andreas fault to faults east of the Sierra Nevada. Potential earthquake magnitudes for these faults range from ~M6.5-7.2 based on surface rupture lengths and documented single-event offsets. The <6-4 Ma central CBR faults appear to accommodate a change in shape of the rock volume between the strike-slip faults on the west and the Colorado Plateau to the east. We suggest that the shape change results from NW-motion of strike-slip fault blocks in the west and deformation on long segmented normal faults in the east.
DE: 8036 Paleoseismology (7221)
DE: 8109 Continental tectonics: extensional (0905)
SC: Tectonophysics [T]
MN: Fall Meeting 2005