HR: 0800h
AN: S51A-0982    [Abstracts]
TI: Seismic imaging of a subducted ridge, southern Chile
AU: * Miller, M
EM: mrm33@cam.ac.uk
AF: Bullard Laboratories, Dept Earth Sciences, University of Cambridge, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Bataille, K
EM: klaus@depto.sismos.udec.cl
AF: Departamento Ciencias de la Tierra, Universidad de Concepcion, Cabina No 12 - Casilla, Concepcion, 160C Chile
AU: Priestley, K
EM: keith@esc.cam.ac.uk
AF: Bullard Laboratories, Dept Earth Sciences, University of Cambridge, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Iwamori, H
EM: hikaru@eps.s.u-tokyo.ac.jp
AF: Department of Earth and Planetary Sciences, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033 Japan
AU: Calisto, I
EM: calisto@depto.sismos.udec.cl
AF: Departamento Ciencias de la Tierra, Universidad de Concepcion, Cabina No 12 - Casilla, Concepcion, 160C Chile
AB: Recent thermal modeling suggests that subduction of an active spreading ridge or a young oceanic plate can cause extensive magmatism, generating granitic melts and metamorphism which may lead to a significant volume of new continental crustal material. We report on a seismic experiment designed to constrain a number of input parameters to this thermal modeling such as the geometry of the subducting plate and the fine scale seismic velocity and attenuation structure. The simple plate geometry of the Chile triple junction makes it an ideal place to study the effects of ridge subduction. We have installed a network of 60 broadband seismometers in southern Chile just east of the triple junction to study the seismicity, the plate geometry and the velocity and attenuation structure of this region. The seismographs are installed from La Tapera (~44.6°S) in the north to Villa O'Higgins (~48.3°S) in the south. Here we report preliminary results from this seismic network. Local events in this region fall into three categories - those associated with the Liquie-Ofqui fault, those associated with the ridge subduction and a concentration of events beneath Volcano Hudson. The joint inversion of short period surface wave dispersion and receiver function data show the existence of a pronounced crustal low velocity zone beneath western Lago General Carrera region which coincides with the projected location of the most recent subducted ridge segment.
DE: 7205 Continental crust (1219)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 7245 Mid-ocean ridges
DE: 7280 Volcano seismology (8419)
SC: Seismology [S]
MN: Fall Meeting 2005