HR: 17:40h
AN: S44B-07    [Abstracts]
TI: Attenuation Tomography of Western North America Using USArray Body Waves
AU: * Wysession, M E
EM: michael@wucore.wustl.edu
AF: Washington University, Dept Earth and Planetary Sci, Campus Box 1169, St Louis, MO 63130, United States
AU: Heeszel, D
EM: davidh@levee.wustl.edu
AF: Washington University, Dept Earth and Planetary Sci, Campus Box 1169, St Louis, MO 63130, United States
AU: Lawrence, J F
EM: jlawrence@ucsd.edu
AF: Stanford University, Dept Geophysics, 397 Panama Mall, Mitchell Bldg 360, Stanford, CA 94305, United States
AU: Huhmann, B
EM: blhuhman@artsci.wustl.edu
AF: Washington University, Dept Earth and Planetary Sci, Campus Box 1169, St Louis, MO 63130, United States
AB: We present P- and S-wave attenuation models for western North America, using the latest up-to-date EarthScope USArray seismic data. Tomographic models of P and S waves are done separately, using a least-squares inversion with a volume parameterization beneath the USArray stations. We find that there is strong correlation between the P and S models, as well as with corresponding velocity models, which match up well with the tectonic structure of the western US. For instance, both show high-attenuation beneath Nevada down to 150 km, in agreement with previous attenuation models done with techniques like Lg-wave attenuation. The seismic attenuation measurements are found in a relative sense, through a multi-waveform cross- correlation method that compares the t* value of a set of like phases (such as S, ScS, SS, P, PP, sS, pP, etc.). The process is automated, so that large numbers of phases can be analyzed quickly. This automation involves removing waveforms with low signal-to-noise ratios by making sure that they reasonably correlate with some minimum number of other phases. This is done in both the time and spectral domains. We also determine velocity anomalies using the same data set, and use the relative t* values to correct the travel-time delays, as we did in Fisher et al. [2003]. In addition, we also use differential t* values by comparing different phases from the same seismograms (like ScS/S, SS/S, PP/P, etc.), as we did in Lawrence and Wysession [2006]. As USArray moves across the country, we will continue to extend our tomographic imaging eastward.
DE: 7203 Body waves
DE: 7205 Continental crust (1219)
DE: 7218 Lithosphere (1236)
DE: 7270 Tomography (6982, 8180)
DE: 8162 Rheology: mantle (8033)
SC: Seismology [S]
MN: 2007 Fall Meeting