Current deformation in Hispaniola from InSAR--derived surface velocities

Bryan Raimbault , Romain Jolivet, Eric Calais , Steeve Symithe, Christian Emmanuel

The oblique convergence between the Caribbean and North American plates is accommodated, in Hispaniola, by left-lateral strike-slip on two major left--lateral fault systems and by intra-arc shortening. We apply a Persistent Scatterer Interferometry (PSInSAR) approach to Sentinel-1 data using six tracks acquired between 2016 and 2023 to generate time series of interseismic velocities over the entire island. We merge the resulting ascending and descending tracks with GNSS--derived velocities to determine a spatially-continuous 3D velocity field that documents deformation gradients across large fault systems. The Enriquillo fault fits a single locked--fault model, while the Septentrional one likely involves several sub--faults. Strain in southeastern Haiti and the southwestern Dominican Republic is well modeled by the J\'er\'emie-Malpasse-Bahoruco oblique reverse fault-system , which represents a significant, but overlooked, regional hazard source.