HR: 17:20h
AN: S44A-05 INVITED     [Abstracts]
TI: Subduction of the Chile Ridge Imaged by Teleseismic Travel-time Inversion
AU: * VanDecar, J C
EM: vandecar@dtm.ciw.edu
AF: Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Road NW, Washington, DC 20015, United States
AU: Russo, R M
AF: University of Florida, Department of Geological Sciences, Gainesville, FL 32611, United States
AU: Mocanu, V I
AF: University of Bucharest, Department of Geophysics, Bucharest, Romania
AU: Gallego, A
AF: University of Florida, Department of Geological Sciences, Gainesville, FL 32611, United States
AU: Comte, D
AF: Universidad de Chile, Departamento de Geofisica, Santiago, 651-1227, Chile
AU: Murdie, R E
AF: Vienna International Centre, Wagramer Strasse 5, Vienna, 1400, Austria
AU: van der Lee, S
AF: Northwestern University, Department of Geological Sciences, Evanston, IL 60208, United States
AB: Making use of teleseismic data recorded at 46 seismic stations deployed in southern Chile from December 2004 to February 2007 (see the Chile Ridge Subduction Project; http:seismology.geology.ufl.edu/chile), we present a preliminary inversion for the mantle P-wave velocity structure beneath the region. The area covered by the network (42-46 degrees South and 72-78 degrees West) lies above the projected position of the subducted Chile ridge, which separates the Nazca and Antarctic oceanic plates. Because the Nazca plate subducts nearly 5 cm/yr faster than the Antarctic plate, the trailing edge of the last Nazca lithosphere formed before the ridge subducts has been inferred to separate steadily from the leading edge of the Antarctic lithosphere, forming progressively larger slab windows with depth. We use the teleseismic inversion to test models for such slab windows. The P-wave relative delay times are obtained via a multi-channel cross correlation of band-passed waveforms for each teleseismic event. These data are then inverted using an iterative, robust, non-linear scheme which parameterizes the 3-D velocity variations as splines under tension constrained at over 30,000 nodes beneath the region.
UR: http:seismology.geology.ufl.edu/chile
DE: 7200 SEISMOLOGY
DE: 7203 Body waves
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 7270 Tomography (6982, 8180)
SC: Seismology [S]
MN: 2007 Joint Assembly