Oblique convergence between the Caribbean (CAR) and North American (NOAM) plates near Hispaniola and the island’s observed clockwise rotation have led to competing hypotheses to explain its tectonics. Clockwise rotation of Hispaniola could be the result of slab edge push generated by (a) subducting NOAM plate, (b) two subducted lithospheric slabs, one southward-dipping from the NOAM plate and one northward-dipping from the CAR Plate at the Muertos Trough interacting at depth, or (c) collision with the carbonate Bahamas Platform. Any of these scenarios or a combination of them can cause intermediate-depth earthquakes. Examining the location of intermediate depth earthquakes along with regional tomography, recorded via a dense temporary network of seismic stations, has the potential to resolve differences between competing hypotheses.

A new 1D P velocity model was determined and then used as a starting model for iterative, nonlinear inversion for 3D structure. A catalog of over 2000 teleseismic events and 200 moderate-sized local events recorded by a total of 30 stations during the interval 2013-2017 is used. The catalog averages 25 P and S wave arrival picks per event with the largest local event magnitude being 5.8. While some events are located as deep as 185 km, over 80% are shallower than 35 km. The intermediate-depth earthquakes appear to be associated with a slow P velocity anomaly. The shape of the slow anomaly suggests a southward-dipping NOAM subducting slab with a change in dip from 30° to 50° at ~67 km depth. Deeper intermediate-depth earthquakes mark the leading edge of the feature we interpret to be the NOAM slab at ~100 km depth. A slow velocity zone extends to the surface beneath central Hispaniola and may be associated with the uplifted Cordillera Central, which includes Pico Duarte, the highest point in the Caribbean. There is no indication in the tomography of a northward-dipping CAR slab subducted beneath eastern Hispaniola.