HR: 17:00h
AN: T34B-05 INVITED    [Abstracts]
TI: The Subducted Chile Ridge Imaged with 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
EM: rrusso@ufl.edu
AF: University of Florida, Department of Geological Sciences, Gainesville, FL 32611, United States
AU: Mocanu, V I
EM: mocanu@gg.unibuc.ro
AF: University of Bucharest, Department of Geophysics, Bucharest, 70139, Romania
AU: Gallego, A
EM: agallego75@gmail.com
AF: University of Florida, Department of Geological Sciences, Gainesville, FL 32611, United States
AU: Comte, D
EM: dcomte@dgf.uchile.cl
AF: Universidad de Chile, Departamento de Geofisica, Santiago, 651-1227, Chile
AU: Murdie, R E
EM: ruth.murdie@ctbto.org
AF: Vienna International Centre, CTBTO P.O. Box 1200, Vienna, 1400, Austria
AU: van der Lee, S
EM: suzan@earth.northwestern.edu
AF: Northwestern University, Department of Geological Sciences, Evanston, IL 60208, United States
AB: We present a teleseismic travel-time inversion for upper-mantle velocity structure beneath the Chile triple junction region. Data were recorded at 46 seismic stations deployed in southern Chile from December 2004 to February 2007 (for details, see the Chile Ridge Subduction Project, http://seismology.geology.ufl.edu/chile). 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. The 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.. We image a high-velocity slab in the upper mantle dipping steeply to the East, which we associate with the subducted Nazca oceanic lithosphere, and a distinct low-velocity anomaly at the projected location of the subducted Chile ridge.
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: Tectonophysics [T]
MN: 2007 Fall Meeting