Seismic hazard along the southern boundary of the Gônave microplate: block modelling of GPS velocities from Jamaica and nearby islands, northern Caribbean

Abstract

We use block modelling of GPS site velocities from Jamaica and nearby islands, including Hispaniola, to test alternative plate boundary geometries for deformation in Jamaica and estimate slip rates along the island's major fault zones. Relative to the Caribbean Plate, GPS sites in northern Jamaica move 6.0 ± 0.5 mm yr−1 to the WSW, constituting a lower bound on the motion of the Gônave microplate across its southern boundary in Jamaica. Obliquely convergent motion of all 30 GPS sites on and near Jamaica relative to the island's ∼E—W-trending strike-slip faults may be partitioned into 2.6 ± 0.6 mm yr−1 of ∼N—S shortening across submarine faults south of Jamaica and 5–6 mm yr−1 of E—W motion. Guided by geological and seismic information about the strikes and locations of faults in Jamaica, inverse block modelling of the regional GPS velocities rejects plate boundary configurations that presume either a narrow plate boundary in Jamaica or deformation concentrated across a restraining bend defined by the topographically high Blue Mountains of eastern Jamaica. The best-fitting models instead place most deformation on faults in central Jamaica. The 4–5 mm yr−1 slip rate we estimate for the Plantain Garden fault and Blue Mountain restraining bend of southeastern Jamaica implies significant seismic hazard for the nearby capital of Kingston.