Assessing earthquake potential and fault activity from a newly estimated high-resolution geodetic velocity field in Hispaniola

Abstract

The transpressive plate boundary between the Caribbean and North American plates in Hispaniola is a complex system of strike-slip faults, subduction zones, fold-and-thrust belts, and normal faulting. Tectonic deformation studies in this region have traditionally relied on sparse Global Navigation Satellite System (GNSS) networks. Here we present a new assessment of deformation in Hispaniola using a dense 3D velocity field generated by integrating existing GNSS observations with new Interferometric Synthetic Aperture Radar (InSAR) velocities. Our InSAR processing approach utilizes phase linking, statistically-based multi-looking, and wrapped phase time-series estimation to mitigate noise, and a spatial covariance model of the troposphere to reduce its effect on the time-series estimation. We use the resulting high-resolution velocity field to calculate strain rates and model crustal faulting in Hispaniola. Strain rate tensors show a transpressional tectonic regime consistent with expectations from the regional tectonics. Modeling results indicate that the Septentrional-Oriente Fault zone is nearly fully locked with moment accumulation consistent with a Mw 7.9 earthquake every 300 years, while the Enriquillo-Plantain Garden Fault is almost fully creeping at the western end of the fault and has a much lower moment accumulation rate.