Caribbean plate boundary seismotectonic in the Lesser and Greater Antilles

Understanding processes that may be at the origin of major earthquakes in subduction zones is highly challenging, especially in the case of slowly converging areas. Here we compile several studies about the spatiotemporal variation of seismicity along the boundary of the Caribbean plate, which evolving from westward subduction in the Lesser Antilles to southward subduction in the Greater Antilles and oblique collision against the Bahamas platform in Cuba. Analysis of several clusters of seismicity associated with the computing of focal mechanisms show that:

- There is an increase in seismicity rate and cumulative seismic moment over the last two decades offshore Martinique island and, particularly, in the presumed rupture area of the major historical 1839 earthquake. This sustained seismicity is shared between extensive intermediate depth activity and a compressive seismic cluster located in the seismogenic zone of the subduction zone.

- The analysis of moment tensors for the Haiti upper lithosphere indicates that normal, thrust and strike-slip faulting are present but with a majority of thrust faulting. The mean P and T axes for the moment tensors indicated that the current compressional deformation is mainly N-S to NNE-SSW. Moreover, a dozen intermediate-depth earthquakes (>70 km) are located under Haiti, and tend to confirm the existence of a lithospheric slab inherited from southward subduction under the Greater Antilles.

- New moment tensors for earthquakes along the southeastern coast of Cuba from 2015 to the end of 2024 are consistent with the tectonic environment of the region. Reverse-oblique focal mechanisms and north dipping fault planes are predominant, particularly around the Santiago Deformed Belt, where insights of the underthrusting of the Gonâve Microplate beneath the Cuban Island are present.

- The eastward progression of major earthquakes (M > 6.8) along the northern boundary of the Caribbean plate in the past 20 years, characterized by strike-slip faulting, reflects the effect of a highly coupled region and the eastward motion of the plate. This trend suggests a potential temporary increase in seismic hazard along the southern coast of Cuba.

Overall, the strain accommodated along the Caribbean plate boundary seems to be highly partitioned between major structures that could produce strong earthquakes and multiple satellites faults that produce regularly low to medium events.