This research proposes a new model of slab geometry beneath the Dominican Republic (DR), which faces the most significant seismic risk in the region, based on the relocation of earthquakes dating from 1964 to Aug. 2010, using the Modified Joint Hypocenter Determination (MJHD) method. Subduction thrust events represent the higher seismic risk for Hispaniola and the Septentrional (SFZ), Camu, and Enriquillo Plantain Garden (EPGFZ) faults show the seismic risk of strike slip earthquakes, where the SFZ represents the most imminent risk.
We found that the North American and Caribbean slabs converge beneath the central area of DR, between 69.9˚W – 69.3˚W. In our model we explain that the deeper area (69.1˚W – 68.2˚W) in southeastern Hispaniola belongs to the Caribbean slab as it evidences continuity of seismicity of Caribbean slab and as the available focal mechanisms of the down–dip extension type, while earthquakes deeper than 110 km belong to the subducting Atlantic slab in the previous model. The Wadati – Benioff zone in the southeastern part of the island of Hispaniola reaches around 180 km in depth.
We also found that the seismogenic slab on northwest of DR reaches until SFZ, while northeast extend beyond this limit. The Camu Fault was responsible for the 2003 Puerto Plata Earthquake (Mw 6.4), with multiples gaps around these two faults.
We also relocated the 1946 Northern Hispaniola Earthquake (Mw 7.9) and almost two years of aftershocks related with this mainshock. The area of the aftershocks distribution for 1946 Northern Hispaniola Earthquake was confirmed as being between 70.4˚W – 68.4˚W and 18.9˚N – 20.0˚N.