HR: 0800h
AN: S51E-1063    [Abstracts]
TI: Receiver Function Analysis of the upper mantle Beneath Northern California
AU: * Brown, S
S51E-1063 AF: Texas Tech, Dept. of Geosciences Texas Tech University, Lubbock, TX 79415 United States
AU: Gurrola, H
EM: harold.gurrola@ttu.edu
AF: Texas Tech, Dept. of Geosciences Texas Tech University, Lubbock, TX 79415 United States
AB: We will present results from common midpoint stacking of receiver functions to image the upper mantle beneath Northern California using data from the Berkley Seismic Network (BSN) and the EarthScope Big Foot stations. The BSN includes a very dense distribution of stations in and round the Bay area thinning to only a handful of stations near the Oregon boarder. The results discussed in this abstract were based on images using receiver functions that were low pass filtered at 0.2, 0.4, 0.6 and 0.8 Hz. Depth variations to the 660 km discontinuity beneath this region does not appear to correlate with any surface tectonic features. The 660 km discontinuity beneath the southern part of this region, 34 to about 39 degrees, exhibits a second phase near the 720 km depth similar to that observed by Simmons and Gurrola, 2000 beneath southern California. The 660 north of 39 degree latitude does not appear to have this deeper phase. The 410 km discontinuity is deepest, implying high temperatures, to the northwest beneath the Modoc and Basin and Range regions. The 410 is shallowest to the west beneath the Northern California coast which implies lower temperatures. There appears to be a strong 220 km discontinuity beneath the northern part of the image but the geometry of this feature suggests that it may be the base of the subducting lithosphere. The later interpretation of this feature together with the presence of a shallower lithspheric phase are consistent with a westward dipping lithospheric plate about 100 km thick.
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7218 Lithosphere (1236)
SC: Seismology [S]
MN: Fall Meeting 2005