According to USGS, Puerto Rico and surrounding areas in the Caribbean have been rocked by 8 earthquakes in the last 24 hours, including two rated over a 4.0 magnitude event. Despite the shaking, there is no threat of tsunami around Puerto Rico, the Virgin Islands, or the U.S. east coast at this time.
Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases. According to the National Ocean Service, the speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters. While tsunamis are often referred to as tidal waves, this name is discouraged by oceanographers because tides have little to do with these giant waves. This recent seismic activity around Puerto Rico was not substantial enough to generate a tsunami.
According to USGS, earthquakes have rocked Pedasi, Guanica, Boca de Yuma, with most, including the strongest, striking at Guanica, where a magnitude 4.4 struck yesterday. Earthquakes of this magnitude can create damage. However, there have been no reports of injuries at this time.
Most of the recent earthquakes in Puerto Rico and the Virgin Islands aren’t far from the epicenter of a strong earthquake that hit in January 2020. That 6.4 created extensive damage in Puerto Rico, including widespread power failures across much of the island. An earthquake swarm started here in December 2019 and unrest has continued since.
These earthquakes are occurring near the northern edge of the Caribbean Plate, a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off of the north coast of South America. The Caribbean Plate borders the North American Plate, the South American Plate, the Nazca Plate, and the Cocos Plate. The borders of these plates are home to ongoing seismic activity, including frequent earthquakes, occasional tsunamis, and sometimes even volcanic eruptions.
The U.S. Government holds annual tsunami drills for the U.S. East and Gulf Coasts each spring with a variety of international agencies and partners. While Hawaii, Alaska, and the U.S. West Coast are more prone to earthquakes and tsunami, catastrophic tsunami could occur on the east coast too from seismic activity here.
