HR: 17:15h
AN: S14A-06 INVITED    [Abstracts]
TI: Reflectors Here, Reflectors There ... Reflectors Everywhere?
AU: * Lawrence, J F
EM: jfl77@stanford.edu
AF: Department of Geophysics Stanford University, 397 Panama Mall Mitchell Building 360, Stanford, CA 94305-2215, United States
AU: Shearer, S M
EM: pshearer@ucsd.edu
AF: IGPP, SIO, UCSD, IGPP 0225 9500 Gilman Drive, La Jolla, CA 92123-0225, United States
AB: Much of global seismology focuses on the direct waves (P and S), with less consideration for reflected waves from major interfaces like SS (reflected at the surface), and even less attention given to smaller amplitude reflected waves such as S660S (the underside shear-wave reflection off the 660-km discontinuity), which provide valuable constraints on mantle discontinuity structure. These phases are generally of such low amplitude that waveform stacking is required to increase their signal-to-noise. Here, we examine SS and ScS precursors respectively for bottom and topside mantle reflections using all the available data in the IRIS FARM database. Previous studies have shown that the globally coherent mantle reflectors are only imaged near 410, 520 and 660 km. However, the possibility remains that regional reflectors at other depths may be common, but they are too intermittent or have too much topography to appear in global data stacks. We search for robust regional reflectors by performing common bouncepoint stacks at 1 km depth intervals and 400 km lateral spacing. We apply weights based on the reflection angle and the signal-to-noise ratio of the direct SS and ScS phases and use bootstrap resampling to constrain the reliability of the imaged reflectors. We report on observed major and minor global reflectors as well as robust regional anomalies and compare our results with those obtained in other studies.
DE: 7203 Body waves
DE: 7218 Lithosphere (1236)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 7270 Tomography (6982, 8180)
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting