The Lesser Antilles arc is approximately 850 km long, with a radius of
curvature about 450 km. The magmatic arc splits north of Martinique with
the outer arc islands, known as the Limestone Caribbes, having a calcareous
cover, and the inner arc containing young volcanic islands. The recent
or active volcanic islands are known as the Volcanic Caribbes.
The Puerto Rico trench is the topographical expression of the subduction
of the Atlantic plate under the Caribbean plate. These plates converge
at a rate of 2 cm per year, with the subducting slab presently being located
at 120-180 km below the present line of volcanoes.
The Puerto Rico trench terminates on the eastern side of the Lesser Antilles
and progressively rises southward into the Barbados accretionary prism.
The accretionary prism is the result of sediment being scraped off the
Atlantic plate and being "piled" up in trench as the plate is being subducted.
Plate locations in the Caribbean region
Topography and bathymetry of the Caribbean
A closer look at the island types (sedimentary or volcanic) and trench