When we think of tsunamis, we often think of an asteroid hit in one of the oceans or an earthquake in a faraway place like Indonesia, where they certainly have occurred before. Recall the Great Asian Tsunami of 2004.

But actually, the threat is much closer to home.

One speaks here of Puerto Rico.

Just off its northern shore in a trench that is both the deepest part of the entire Atlantic Ocean and also a hotbed of seismic activity, witnessed just last week with a magnitude-five on March 31.

At least fifty earthquakes have struck along the Puerto Rican Trench region north of the Virgin Islands since April 1, with six reported Good Friday morning.

An epic quake in that trench could produce catastrophic local tsunami impacts for places such as San Juan and Arecibo, and recent USGS work found evidence of a very large prehistoric tsunami affecting Puerto Rico between about 1470 and 1530.all of Puerto Rico.

It could send a tsunami to parts of the East Coast, including Virginia Beach. Mid-Atlantic coastline seems most at risk, but parts of Florida could also feel it as could places such as Dukes County, Massachusetts, where a magnitude 9.0 event in the trench could send a tsunami with an estimated arrival time of about four hours and thousands of people in the inundation zone.