HR: 0800h
AN: S41A-0253    [Abstracts]
TI: Lg and Pg Attenuation in the Middle East
AU: * Sandvol, E
AF: University of Missouri, Department of Geological Sciences, University of Missouri, Columbia, MO 65211, United States
AU: Bao, X
AF: University of Missouri, Department of Geological Sciences, University of Missouri, Columbia, MO 65211, United States
AU: Zor, E
AF: Earth Science Institute, Turkey, TUBITAK Marmara Research Center, Earth Science Institute, Kocaeli, 41470, Turkey
AU: Xie, J
AF: AFRL/VSBYE, 29 Randolph Rd. Hanscom AFB, Bedford, MA 01731, United States
AU: Mitchell, B J
AF: St. Louis University, Earth and Atmosphere Sciences, 329 Macelwane Hall, 3507 Laclede Ave., St. Louis, MO 63103, United States
AU: Schaff, D P
AF: Lamont-Doherty Earth Observatory, 61 Route 9W - PO Box 1000, Palisades, NY 10964- 8000, United States
AB: In order to construct reliable frequency-dependent Q models for both Lg and Pg phases, we have analyzed approximately 8000 waveforms from approximately 500 events recorded by 11 permanent and temporary networks throughout the Middle East. We have developed a frequency dependent-Q tomographic model for both direct Lg and Pg. In general, we found low Q within the plateau and high Q within the stable Arabian plate. We found that the Pg Q does not vary as much as Lg Q, however, the general trend is the same. The frequency dependent exponent for Lg is less than that of Pg in the Middle East. Resolution tests of 2x2 cell size for Q tomography in our work indicate that we have very good resolution throughout much of the Anatolian Plateau resolution of anomalies larger than 200km in the northern Arabian plate. We have begun the work on validating our Lg and Pg attenuation models. We are developing a catalog of ¡°amplitude ground truth¡± seismic events. We are applying these events to test whether path corrections from our attenuation models can successfully predict the source spectra (i.e., moment and corner frequency). In order to develop a catalog of events with reliable event spectra, a search was performed on 373 events at 89 stations in the Middle East to look for doublets and repeating earthquakes. Only one pair met the same criteria for repeating events as were used in China. This is 1% of the seismicity, as compared to 9% from all the currently available waveforms in China (1,301 events out of ~14,000). This difference may be due to the absence of magnitude 3.0s from the Middle East data set; these events would probably have a greater chance of having similar waveforms due to simpler rupture areas and closer proximity to one another. This catalog of similar waveforms will also allow us to calibrate and adjust our model to better predict reliable source spectra.
DE: 6982 Tomography and imaging (7270, 8180)
DE: 7203 Body waves
DE: 7205 Continental crust (1219)
DE: 7270 Tomography (6982, 8180)
DE: 8180 Tomography (6982, 7270)
SC: Seismology [S]
MN: 2007 Fall Meeting