From transcurrent faulting to frontal subduction: A seismotectonic study of the Northern Caribbean Plate Boundary from Cuba to Puerto Rico

Abstract

Recent marine and onland geophysical and geological investigations along the northern Caribbean plate boundary call for a review of its tectonic interpretation, in the light of a new compilation of the seismological data avalaible from Cuba to Puerto Rico. We show that the shallow seismicity in the northeastern Caribbean is concentrated along an east‐west trending lineament corresponding to the trace of the major strike‐slip fault system. The most intense seismicity is located around restraining bends such as southern Cuba and northern Hispaniola. The stress and strain distribution deduced from focal mechanisms and microtectonic analysis lead us to infer a small N‐S convergence component associated with the major eastward strike‐slip motion of the Caribbean plate versus North America. Earthquake distribution and focal mechanisms suggest the existence of a lithospheric slab inherited from the frontal subduction under the Lesser Antilles diping down under Puerto Rico and eastern Hispaniola. We propose a model in which this slab is disconnected from the Atlantic oceanic lithosphere by transcurrent faulting along the plate boundary.