HR: 1340h
AN: T53A-1412    [Abstracts]
TI: 3-D Seismic Tomography of the Mariana Mantle Wedge From the 2003-2004 Passive Component of the Mariana Subduction Factory Imaging Experiment
AU: * Barklage, M
EM: mitchb@seismo.wustl.edu
AF: Washington University, 1 Brookings Dr. Campus Box 1169, St. Louis, MO 63130 United States
AU: Conder, J
T53A-1412 AF: Washington University, 1 Brookings Dr. Campus Box 1169, St. Louis, MO 63130 United States
AU: Wiens, D
T53A-1412 AF: Washington University, 1 Brookings Dr. Campus Box 1169, St. Louis, MO 63130 United States
AU: Shore, P
T53A-1412 AF: Washington University, 1 Brookings Dr. Campus Box 1169, St. Louis, MO 63130 United States
AU: Shiobara, H
T53A-1412 AF: Earthquake Research Institute University of Toyko, 1-1-1 Yayoi Bunkyo-ku, Toyko, 113-0032 Japan
AU: Sugioka, H
T53A-1412 AF: IFREE JAMSTEC, 2-15 Natsushima-Cho, Yokosuka, 237-0061 Japan
AB: High-resolution 3D P-wave velocity structure of the Mariana island-arc and back-arc is determined from body-wave arrival times recorded by 48 ocean bottom seismographs and 20 land based seismometers deployed from June 2003-May 2004. We use ~10,000 P-wave arrival times from ~500 of the largest local events that occurred during the recording period to invert for the seismic velocity structure. Outgoing teleseismic arrival times reported by the PDE bulletins are also used to further constrain the structure and earthquake locations. Additionally, incoming teleseismic arrival times from large teleseismic events are determined using multi-channel cross correlation, providing travel time data that is insensitive to local earthquake locations. An iterative procedure was used during the inversion, in which earthquakes are relocated and rays are retraced through the structure between each iteration via a bending method. Preliminary results reveal some interesting features that will provide constraints on geodynamic processes of the Mariana subduction factory. The slab anomaly is resolved down to depths of 600 km. A slow velocity anomaly of ~8% is present within the upper 150 km beneath the Mariana back-arc spreading center. Slow velocity anomalies are also found within the upper 100 km beneath the active volcanic arc and in the uppermost fore-arc mantle. Slow upper mantle velocities in the uppermost fore-arc could be indicative of widespread serpentinization of the mantle. The deeper portion of the forearc (50-100 km depth) shows fast velocities, indicating cold, unserpentinized mantle.
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8180 Tomography (6982, 7270)
SC: Tectonophysics [T]
MN: Fall Meeting 2005