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Preprints Archive: Abstract of IC2010032 (2010)

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S-wave's velocities of the lithosphere-asthenosphere system in the Caribbean region

by O'Leary Gonzalez, Jose Leonardo Alvarez, Bladimir Moreno and Giuliano F. Panza

Document info: Pages 25, Figures 9.

An overview of the S-wave velocity (Vs) structural model of the Caribbean is presented with a resolution of 2$^\circ$ox2$^\circ$. As a result of the frequency time analysis (FTAN) of more than 400 trajectories epicenter-stations in this region, new tomographic maps of Rayleigh waves group velocity dispersion at periods ranging from 10 s to 40 s have been determined. For each 2$^\circ$x2$^\circ$ cell, group velocity dispersion curves were determined and extended to 150 s adding data from a larger scale tomographic study (Vdovin et al., 1999). Using, as independent a priori information, the available geological and geophysical data of the region, each dispersion curve has been mapped, by non-linear inversion, into a set of Vs vs. depth models in the depth range from 0 km to 300 km. Due to the non-uniqueness of the solutions for each cell a Local Smoothness Optimization (LSO) has been applied to the whole region to identify a tridimensional model of Vs vs. depth in cells of 2$^\circ$x2$^\circ$, thus satisfying the Occam razor concept. Through these models some main features of the lithosphere and asthenosphere are evidenced, such as: the west directed subduction zone of the eastern Caribbean region with a clear mantle wedge between the Caribbean lithosphere and the subducted slab; the complex and asymmetric behavior of the crustal and lithospheric thickness in the Cayman ridge; the diffused presence of oceanic crust in the region; the presence of continental type crust in the South America, Central America and North America plates, as well as the bottom of the upper asthenosphere that gets shallower going from west to east.

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