The 2020 Magnitude 7.7 Earthquake Northwest of Jamaica

On January 28, 2020, at 19:10 UTC, a magnitude 7.7 earthquake struck 123 km NNW of Lucea, Jamaica, at a depth of 14.8 km. This event stands as the strongest recorded in the region since 2000. The quake resulted from strike-slip faulting along the boundary between the Caribbean and North American tectonic plates, where lateral motion accommodates regional plate convergence.

Jamaica occupies a position within the Gonâve microplate, a fragment caught between the larger Caribbean and North American plates. The island experiences frequent seismic activity due to transform faults that accommodate eastward motion of the Caribbean plate relative to North America at rates of approximately 19–20 mm per year. The 2020 rupture occurred on a segment of the Oriente fault system, consistent with the region’s history of left-lateral strike-slip events.

Historical records document damaging earthquakes affecting Jamaica since the 17th century, including the destructive 1692 Port Royal event and the 1907 Kingston earthquake, both linked to nearby fault segments. Modern instrumental data confirm ongoing seismicity along the plate boundary, with the 2020 event notable for its size and offshore location, which limited direct structural damage on land while generating felt shaking across Jamaica, Cuba, and parts of the southeastern United States.

Following the mainshock, aftershock activity remained elevated for weeks, consistent with patterns observed after other large strike-slip earthquakes in the Caribbean. No significant tsunami was generated, owing to the event’s strike-slip mechanism and moderate focal depth.

Regional Tectonic Setting

The northern Caribbean plate boundary comprises a complex system of faults, including the Septentrional-Oriente fault zone and the Enriquillo-Plantain Garden fault zone. These structures have produced multiple magnitude-7+ events over the past century. Jamaica’s geology reflects this tectonic regime through uplifted carbonate platforms and active fault scarps visible in the landscape.

Seismic Hazard Context

Seismic hazard assessments for Jamaica incorporate both historical and instrumental catalogs. The 2020 earthquake underscores the potential for infrequent but high-magnitude events along offshore faults, informing updates to building codes and preparedness strategies in the northern Caribbean.

References
USGS Earthquake Hazards Program event page for the 28 January 2020 M7.7 Jamaica earthquake
Global Centroid Moment Tensor (GCMT) catalog
Caribbean tectonic framework studies from the U.S. Geological Survey Professional Papers