HR: 0800h
AN: S41A-0239    [Abstracts]
TI: High Resolution Receiver Functions From the Southern Great Basin, Nevada
AU: * Dean, A M
EM: adean@mines.edu
AF: Colorado School of Mines, Department of Geophysics 1500 Illinois St, Golden, CO 80401, United States
AU: Schulte-Pelkum, V
EM: vera_sp@cires.colorado.edu
AF: University of Colorado Boulder, CIRES/Department Geological Sciences 2200 Colorado Ave UCB 399, Boulder, CO 80309, United States
AU: Biasi, G P
EM: glenn@seismo.unr.edu
AF: University of Nevada Reno, Seismological Laboratory MS 174, Reno, NV 89557, United States
AU: Sheehan, A F
EM: afs@cires.colorado.edu
AF: University of Colorado Boulder, Department Geological Sciences Campus Box 399, Boulder, CO 80309, United States
AB: The crustal structure based on teleseismic receiver functions from the 30 station short period Southern Great Basin Digital Seismic Network is our focus. The Southern Great Basin Seismic Network is centered on the proposed high level nuclear waste facility at Yucca Mountain, Nevada, on the western edge of the Nevada Test Site. There are approximately thirty 3-component seismometers in the Yucca Mountain region, some of which are located in the Nevada Test Site. Yucca Mountain is located in the Basin and Range physiographic province, and geology in the immediate vicinity consists mostly of Miocene ash flow tuffs. A large north to south variation in Bouguer gravity is centered at latitude 37N, just north of Yucca Mountain, with a 50 mGal variation in Bouguer gravity over 50 km. We seek to determine whether there are crustal thickness variations that correspond to the dramatic gravity variations over these short spatial scales. Radial and transverse component receiver functions for P arrivals are calculated from approximately 400 teleseismic events coving a wide backazimuthal range using a time-domain iterative deconvolution method. A conversion consistent with a sediment layer is seen at a few stations, creating a more complex velocity model for the area. The sediment layer also produces multiple reverberations, interfering with the useful signal. From moveout plots the Moho is visible around four seconds at most stations along with a midcrustal boundary near two seconds at a number of stations. We see large variation with backazimuth of the converted arrivals with polarity changes on both the radial and transverse components, suggesting scattering and complex crustal structure. Robust features are made visible by interstation stacking. Throughout the area we find little variation in crustal thickness, suggesting an origin of the gravity anomaly other than simple crustal thickness. Velocity models from past refraction experiments were used to migrate the observed interfaces to depth. Some of the more interesting azimuthal signals are also discussed.
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: 2007 Fall Meeting