HR: 0830h
AN: S41A-03    [Abstracts]
TI: Simultaneous Inversion of Fundamental Mode and Overtone Group and Phase Speed Maps
AU: * Anderson, D K
EM: dewey.anderson@colorado.edu
AF: Center for Imaging the Earth's Interior, Department of Physics University of Colorado Campus Box 390, Boulder, CO 80309-0390 United States
AU: Ritzwoller, M H
EM: ritzwoll@merckx.colorado.edu
AF: Center for Imaging the Earth's Interior, Department of Physics University of Colorado Campus Box 390, Boulder, CO 80309-0390 United States
AU: Shapiro, N M
EM: nshapiro@fignon.colorado.edu
AF: Center for Imaging the Earth's Interior, Department of Physics University of Colorado Campus Box 390, Boulder, CO 80309-0390 United States
AU: Trampert, J
EM: jeannot@geo.uu.nl
AF: Department of Earth Sciences University of Utrecht, POB 80021 Utrecht, 3508 TA The Netherlands,
AU: van Heijst, H J
EM: hendrik.vanheijst@shell.com
AF: Shell International Exploration and Production, PO Box 60 2280 AB Rijswijk The Netherlands,
AB: The lateral resolution of fundamental mode Rayleigh and Love wave dispersion maps has been improving steadily so that, at present, broadband tectonic-scale maps are available across much of the globe. As bandwidth has increased to include periods below 20 sec, the vertical resolution of shear wave speeds in the crust and upper mantle has also improved dramatically. Fundamental mode measurements, however, provide only relatively weak constraints on structures deeper than about 200 km. Observations of overtone phase speeds provide a useful complement to the fundamental mode observations, and push strong structural constraints to depths through the transition zone. We present the results of a simultaneous inversion of fundmental mode group and phase speeds with phase speed measurement from the first five overtone branches. The inversion is performed in two steps. In the first step, dispersion maps for each wave type are constructed on a grid of periods (e.g., ranging from 16 sec to 150 sec for the Rayleigh and Love wave group speeds). Finite frequency sensitivity kernels are used to construct all maps. In the second step, the dispersion maps are subjected to a Monte-Carlo inversion to estimate the range of seismic models of the crust, upper mantle, and transition zone consistent with the measurements. We discuss the power and limitations of this method, in particular the ability of the overtone measurements to reduce uncertainties in the resulting model.
DE: 7200 SEISMOLOGY
DE: 7218 Lithosphere and upper mantle
DE: 7255 Surface waves and free oscillations
DE: 8180 Tomography
SC: Seismology [S]
MN: 2005 Joint Assembly