HR: 0800h
AN: S41B-0564    [Abstracts]
TI: Ambient seismic noise and teleseismic tomography in the western USA: High-resolution 3-D model of the crust and upper mantle from Earthscope/USArray
AU: * Yang, Y
EM: yingjie.yang@colorado.edu
AF: Center of Imaging the Earth's Interior,University of Coloado at Boulder, 2000 colorado Ave., Boulder, CO 80309, United States
AU: Ritzwoller, M
EM: ritzwoll@anquetil.colorado.edu
AF: Center of Imaging the Earth's Interior,University of Coloado at Boulder, 2000 colorado Ave., Boulder, CO 80309, United States
AU: Moschetti, M
EM: morganm@ciei.colorado.edu
AF: Center of Imaging the Earth's Interior,University of Coloado at Boulder, 2000 colorado Ave., Boulder, CO 80309, United States
AU: Lin, F
EM: linf@colorado.edu
AF: Center of Imaging the Earth's Interior,University of Coloado at Boulder, 2000 colorado Ave., Boulder, CO 80309, United States
AB: This study applies two new complementary methods of surface wave tomography, ambient noise tomography (ANT) and two-plane wave teleseismic tomography (TPWT), to the rapidly accruing data resources in the western US, predominantly from the Transportable Array (TA) component of EarthScope/USArray. Ambient noise tomography (ANT) is based on the extraction of empirical surface-wave Green functions by cross-correlating long sequences of ambient seismic noise. Two plane-wave tomography (TPWT) interprets the variation in amplitude and phase of teleseismic surface waves observed across a regional seismic array in terms of phase velocity variations within the foot-print of the array. Both methods measure surface wave dispersion, but in complementary period bands: ANT (6 - 40 sec) and TPWT (25 - 150 sec). Used in combination, the methods produce surface wave dispersion maps (Rayleigh and Love wave, group and phase velocity) across the western US from about 6 sec to 150 sec period on a 25-50 km geographic grid. Using the combined phase velocity dispersions at periods from 6 sec to 150 sec, we perform 3-D shear velocity inversion to obtain a high-resolution shear velocity model from surface to ~150 km in the W. US. The model possesses a wealth of features. We list only three examples here: the high velocity slab subducting beneath the Cascades in northern California and Oregon overlain by a low velocity upper mantle wedge; a low velocity anomaly beneath the eastern edge of the southern Sierra Nevada and the adjoining Walker Lane region underlain by a high velocity anomaly; and the well-known high velocity anomaly associated with downwelling lithosphere beneath the Transverse Range.
DE: 7205 Continental crust (1219)
DE: 7255 Surface waves and free oscillations
DE: 7270 Tomography (6982, 8180)
SC: Seismology [S]
MN: 2007 Fall Meeting