3-D shear wave velocity model of Mexico and South US: bridging seismic networks with ambient noise cross-correlations (C¹) and correlation of coda of correlations (C³)

This work presents an innovative strategy to enhance the resolution of surface wave tomography obtained from ambient noise cross-correlation (<it>C</it>1) by bridging asynchronous seismic networks through the correlation of coda of correlations (<it>C</it>3). Rayleigh wave group dispersion curves show consistent results between synchronous and asynchronous stations. Rayleigh wave group traveltimes are inverted to construct velocity–period maps with unprecedented resolution for a region covering Mexico and the southern United States. The resulting period maps are then used to regionalize dispersion curves in order to obtain local 1-D shear velocity models (<it>V</it><inf><it>S</it></inf>) of the crust and uppermost mantle in every cell of a grid of 0.4°. The 1-D structures are obtained by iteratively adding layers until reaching a given misfit, and a global tomography model is considered as an input for depths below 150 km. Finally, a high-resolution 3-D <it>V</it><inf><it>S</it></inf> model is obtained from these inversions. The major structures observed in the 3-D model are in agreement with the tectonic-geodynamic features and with previous regional and local studies. It also offers new insights to understand the present and past tectonic evolution of the region.