Current deformation along the northern Caribbean plate boundary from GNSS measurements in Cuba

Abstract

Global Navigation Satellite System (GNSS) measurements at episodic sites or continuously operating stations have been used in most actively deforming regions to determine strain rates, fault slip rates, and contribute to assessing regional seismic hazard. However, the central part of the northern Caribbean plate boundary in Cuba has so far been exempt from sufficient GNSS data to study these classic issues of plate boundary kinematics and the associated hazard. Here, we describe the first position-velocity GNSS solution for Cuba and its close surroundings, providing new information on the seismotectonics of the southern boundary of the North American plate. We find that (1) western and central Cuba are rigidly attached to the North American plate, with internal deformation – if any – that is <1 mm/yr, (2) eastern Cuba shows systematic east-trending residual velocities with respect to the North American plate at 2–4 mm/yr, (3) sites on the Cayman Ridge, although located <50 km from the Oriente fault, show negligible residual velocities with respect to the North American plate. A series of kinematic models shows that the data are best explained by a 10 mm/yr slip deficit between the Gonâve microplate and the North American plate accommodated on a vertical, left-lateral Oriente strike-slip fault with a 25 km locking depth along the eastern Cuban margin, and a much shallower locking depth further west along the Cayman Ridge segment of the Oriente fault, which is possibly creeping. The transition from deep to shallow locking coincides with a drastic change in seismicity distribution, possibly indicative of lateral variation in the stress state or fault rheology along the Oriente fault. Additional GNSS observations and longer time series will help consolidate these initial findings and determine whether and how other active faults may contribute to the seismotectonics of Cuba.