Seismic Evidence for an Active Southern Rio Grande Rift

Competing models exist to explain what caused the formation of the Rio Grande Rift (RGR), a large continental rift that spreads apart the continental lithospheres of the Great Plains and Colorado Plateau. When a rift system breaks apart continental crusts, it is classified as a continental rift and, in this case, the RGR is a primary example of a continental rift. There is a growing body of evidence, which shows that geologic activity still occurs in the RGR, with a continuation of faulting, seismicity and widening at a small rate. We map the crustal thickness and seismic velocity ratio to investigate the regional extension of the Southern Rio Grande Rift (SRGR) and better determine the nature of tectonic activity. In particular, we compute receiver functions and receiver functions stacks for 130 USArray and other seismic stations in the region, plus interpolate the results using the kriging interpolation scheme. We create a subsurface crustal scale model incorporating receiver function, gravity and magnetic information.  We find that the crustal thickness of SRGR thins in the south to east of the current rift, suggesting continuing southern RGR deformation and extension, and an uplifted lower and upper crust that suggests evidence for geothermal activity underneath the central basin of SRGR, highlighting that the rift is likely active.