An overview of the S-wave velocity (Vs) structural model of the Caribbean with a resolution of 2° 9 2° is presented. New tomographic maps of Rayleigh wave group velocity disper- sion at periods ranging from 10 to 40 s were obtained as a result of the frequency time analysis of seismic signals of more than 400 ray-paths in the region. For each cell of 2° 9 2°, group velocity dispersion curves were determined and extended to 150 s by adding data from a larger scale tomographic study (VDOVIN et al., Geo- phys. J. Int 136:324–340, 1999). Using, as independent a priori information, the available geological and geophysical data of the region, each dispersion curve has been inverted by the ‘‘hedgehog’’ non-linear procedure (VALYUS, Determining seismic profiles from a set of observations (in Russian), Vychislitielnaya Seismologiya 4, 3–14. English translation: Computational Seismology (V.I. Keylis- Borok, ed.) 4:114–118, 1968), in order to compute a set of Vs versus depth models up to 300 km of depth. Because of the non- uniqueness of the solutions for each cell, a local smoothness optimization has been applied to the whole region in order to choose a three-dimensional model of Vs, satisfying this way the Occam’s razor concept. Several known and some new main fea- tures of the Caribbean lithosphere and asthenosphere are shown on these models 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 predominant oceanic crust in the region; the presence of continental type crust in Central America, and the South and North America plates; as well as the fact that the bottom of the upper asthenosphere gets shallower going from west to east.
S-Wave Velocities of the Lithosphere–Asthenosphere System in the Caribbean Region
PANZA, GIULIANO
2012-01-01
Abstract
An overview of the S-wave velocity (Vs) structural model of the Caribbean with a resolution of 2° 9 2° is presented. New tomographic maps of Rayleigh wave group velocity disper- sion at periods ranging from 10 to 40 s were obtained as a result of the frequency time analysis of seismic signals of more than 400 ray-paths in the region. For each cell of 2° 9 2°, group velocity dispersion curves were determined and extended to 150 s by adding data from a larger scale tomographic study (VDOVIN et al., Geo- phys. J. Int 136:324–340, 1999). Using, as independent a priori information, the available geological and geophysical data of the region, each dispersion curve has been inverted by the ‘‘hedgehog’’ non-linear procedure (VALYUS, Determining seismic profiles from a set of observations (in Russian), Vychislitielnaya Seismologiya 4, 3–14. English translation: Computational Seismology (V.I. Keylis- Borok, ed.) 4:114–118, 1968), in order to compute a set of Vs versus depth models up to 300 km of depth. Because of the non- uniqueness of the solutions for each cell, a local smoothness optimization has been applied to the whole region in order to choose a three-dimensional model of Vs, satisfying this way the Occam’s razor concept. Several known and some new main fea- tures of the Caribbean lithosphere and asthenosphere are shown on these models 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 predominant oceanic crust in the region; the presence of continental type crust in Central America, and the South and North America plates; as well as the fact that the bottom of the upper asthenosphere gets shallower going from west to east.Pubblicazioni consigliate
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