HR: 1340h
AN: T33B-0552    [Abstracts]
TI: Combined Inversion of Moment Tensors and Site Response - Application to the Northern Chile Subduction Zone
AU: * Schmedes, J
EM: jasch@crustal.ucsb.edu
AF: Institute of Earth Sciences, University of Potsdam, Postfach 60 15 53, Potsdam, 14415 Germany
AU: * Schmedes, J
EM: jasch@crustal.ucsb.edu
AF: Department of Geological Sciences & Instiute of Crustal Studies, University of California, Santa Barbara, 1140 Girvetz Hall, Santa Barbara, CA 93106-1100 United States
AU: Rietbrock, A
EM: A.Rietbrock@liverpool.ac.uk
AF: Department of Earth and Ocean Sciences, University of Liverpool, 4 Brownlow Street, Liverpool, L69 3GP United Kingdom
AU: Krueger, F
EM: kruegerf@geo.uni-potsdam.de
AF: Institute of Earth Sciences, University of Potsdam, Postfach 60 15 53, Potsdam, 14415 Germany
AU: Scherbaum, F
EM: fs@geo.uni-potsdam.de
AF: Institute of Earth Sciences, University of Potsdam, Postfach 60 15 53, Potsdam, 14415 Germany
AB: The information utilized to invert for seismic moment tensors consists of information extracted from seismograms recorded at different stations. In addition, the information of the earthquakes recorded at one station can be used to invert for site response. Hence, it is possible to perform a combined inversion for seismic moment tensors and site response. We utilize spectral amplitudes yielding a nonlinear cost function for the problem. Two approaches, one based on linearization and one hybrid, to solve the nonlinear system of equations are compared using synthetic data which mimic the real station-event geometry of a network which was temporarily installed in northern Chile. For each station in the data set we calculate synthetic seismograms resulting from velocity models with one sub-surface sediment layer. Furthermore, we investigate the influence of norms and constraints on the inverted solutions using the hybrid method. A comparison between moment tensor solutions inverted with a single event technique and the combined inversion is done. Finally, we invert 52 earthquakes which occurred in two planes of seismicity inside the upper region of the subducting lithosphere in northern Chile (M_w∈[2.3,4.5]). First motion polarities are utilized to check the inverted solutions and a bootstrap analysis is applied to quantify uncertainties. Again, a comparison between moment tensor solutions resulting from a single event inversion and the combined inversion is done. Site response amplitude spectra for P-waves are inverted for 31 stations in frequency bands of 0.7-1.5 Hz and 1.0-2.8 Hz. An interpretation of the inverted moment tensors is given by assuming that the observed events occurred in the crust and the upper mantle of the subducting lithosphere.
DE: 3260 Inverse theory
DE: 7215 Earthquake source observations (1240)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Tectonophysics [T]
MN: Fall Meeting 2005