WASHINGTON — Puerto Rico has felt hundreds of aftershocks after the Jan. 7 magnitude 6.4 earthquake. And throughout history, earthquakes are not an unheard-of occurrence on the island. This is because of plate tectonics.

Puerto Rico and the adjacent islands surrounding it are sitting on the convergence between two tectonic plates. The islands are on the edge of the Caribbean Plate, which extends to the south in the Caribbean Sea, while the North American Plate is just north of the island.

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