Crust and Upper Mantle Structure in the Caribbean Region by Group Velocity Tomography and Regionalization

Abstract

An overview of the crust and upper mantle structure of the Central America and Caribbean region is presented as a result of the processing of more than 200 seismograms recorded by digital broadband stations from SSSN and GSN seismic networks. By FTAN analysis of the fundamental mode of the Rayleigh waves, group velocity dispersion curves are obtained in the period range from 10 s to 40 s; the error of these measurements varies from 0.06 and 0.10 km/s. From the dispersion curves, seven tomographic maps at different periods and with average spatial resolution of 500 km are obtained. Using the logical combinatorial classification techniques, eight main groups of dispersion curves are determined from the tomographic maps and eleven main regions, each one characterized by one kind of dispersion curves, are identified. The average dispersion curves obtained for each region are extended to 150 s by adding data from the tomographic study of [3] and inverted using a non-linear procedure. As a result of the inversion process, a set of models of the Swave velocity vs. depth in the crust and upper mantle are found. In six regions, we identify a typically oceanic crust and upper mantle structure, while in the other two the models are consistent with the presence of a continental structure. Two regions, located over the major geological zones of the accretionary crust of the Caribbean region, are characterized by a peculiar crust and upper mantle structure, indicating the presence of lithospheric roots reaching, at least, about 200 km of depth.2

Lithospheric structure below seismic stations in Cuba from the joint inversion of Rayleigh surface waves dispersion and receiver functions

“…The final model for each station is chosen according to the following two criteria: (i) it is the solution with the best percentage of fit for the RFs (see Table 3 and an example of RF fit in Fig. 5), and (ii) it corresponds to a dispersion curve whose difference with the experimental data at each period is within their corresponding experimental errors and the standard error with respect to observed group velocities (Table 3) is less than 0.045 km s –1 , that is equal to the value of rms used by Gonzalez et al (2007).…”

“…Van Der Hilst 1990; Montagner & Kennett 1996) and, more recently, by using the surface wave dispersion analysis (e.g. Vdovin et al 1999; Gonzalez et al 2007, 2011).…”

“…Considering the availability of surface wave's dispersion data in the Caribbean region (Gonzalez et al 2007, 2011) and the recent teleseismic recordings of the stations in Cuba, we perform a joint inversion of RFs and surfaces wave dispersion to constrain, in the region below the seismic stations, the distribution of shear wave velocity versus depth in the lithosphere–asthenosphere system. Where possible, the new results are compared with the ones available in literature.…”

Surface wave tomography across Afar, Ethiopia: Crustal structure at a rift triple-junction zone

“…The tomography method of Yanovskaya and Ditmar [1990]was used to estimate 2D group velocity maps from the observed source‐receiver dispersion measurements on a 0.5 by 0.5 degree grid. This method is a generalization to 2D of the 1D inversion approach of Backus and Gilbert [1968] and has been applied in several papers [e.g., Ritzwoller and Levshin , 1998; González et al , 2007]. The density of paths, the azimuthal coverage, and the average path length control the resolution of the data set.…”