Earthquakes in Puerto Rico: Live Map & the 2020 Indios Swarm

Puerto Rico sits on the northern edge of the Caribbean plate, right next to the boundary with the North American plate, where subduction, strike-slip faulting and crustal extension all interact in a complex tectonic knot. Just north of the island lies the Puerto Rico Trench, the deepest point in the entire Atlantic Ocean at about 8,400 metres, formed where the North American plate begins to dive beneath the Caribbean plate.

The most damaging recent activity struck the island's south-west in a long seismic swarm that began in late December 2019 and peaked on 7 January 2020 with a magnitude 6.4 earthquake near Indios, off the coast close to Guánica and Ponce. One person died and hundreds of buildings were damaged or destroyed across the south-western municipalities, and the area kept recording thousands of aftershocks for months afterward — a pattern that surprised many residents used to hurricanes rather than earthquakes as the island's main hazard.

Puerto Rico's earthquake history includes an even larger event: the magnitude 7.3 San Fermín earthquake of 11 October 1918, centred in the Mona Passage west of the island, which triggered a tsunami that killed around 40 people along the north-west coast near Aguadilla and Mayagüez. The Puerto Rico Seismic Network, run by the University of Puerto Rico at Mayagüez, monitors the island around the clock, and both the trench to the north and the crustal faults beneath the island itself are considered capable of generating strong, damaging earthquakes.