HR: 1340h
AN: T53A-1413    [Abstracts]
TI: Rayleigh Wave Phase Velocity Structure of the Mariana Mantle Wedge From a Combined Array of Land Stations and OBSs
AU: * Pyle, M L
EM: mpyle@artsci.wustl.edu
AF: Washington University, One Brookings Drive Campus Box 1169, St. Louis, MO 63130 United States
AU: Wiens, D A
T53A-1413 AF: Washington University, One Brookings Drive Campus Box 1169, St. Louis, MO 63130 United States
AU: Shore, P J
T53A-1413 AF: Washington University, One Brookings Drive Campus Box 1169, St. Louis, MO 63130 United States
AU: Shiobara, H
T53A-1413 AF: Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Sugioka, H
T53A-1413 AF: IFREE, JAMSTEC, 2-15 Natsushima-Cho, Yokosuka, 237-0061 Japan
AB: We study the shear velocity structure of the upper mantle in the Mariana mantle wedge using Rayleigh wave phase velocities. We obtain interstation and average phase velocity curves from vertical component Rayleigh waves recorded at 10 broadband land stations and 47 ocean bottom seismographs deployed from June 2003 to May 2004. The ocean bottom seismographs show Rayleigh waves with excellent signal to noise ratios at periods from 15-100 seconds. To calculate the phase velocities we cross correlate the phase-matched filters for each station pair. The use of the phase-matched filter is advantageous because it allows for the isolation of the fundamental Rayleigh mode without the contamination of multiples and increases the signal-to-noise ratio. We use array analysis to determine the optimum back-azimuth correction for each event to correct for wavefront distortion from structure along the teleseismic paths outside the array. We then apply the back-azimuth correction to each station pair to determine the interstation phase velocity. Individual phase velocity measurements for pairs of stations are then used in a tomographic inversion to determine the phase velocity structure of the backarc at various periods. We use the average phase velocity across the array from events with a variety of back-azimuths to examine azimuthal anisotropy in the region. Preliminary results resolve slower velocities in the backarc and faster velocities in the forearc, as expected. We also investigate the use of noise correlation methods to determine Rayleigh wave phase and group velocities. This method may offer great advantages for short term deployments of broadband sensors since Rayleigh wave Green's Functions can be determined from noise correlation of only several months of data. Preliminary analysis shows that Rayleigh wave Green's Functions can be observed from noise correlation for many OBS and land station pairs.
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 7255 Surface waves and free oscillations
SC: Tectonophysics [T]
MN: Fall Meeting 2005