The Puerto Rico trench
The movement of tectonic plates beneath the ocean can create waves that travel much farther than those caused by submarine landslides, because they involve the movement of a much larger volume of water, with longer waves that don't quickly dissipate, ten Brink said. The most dangerous earthquakes are those at subduction zones, where one plate dives beneath another.
While the most infamous subduction zones are found around the Pacific Ring of Fire — such as the one that set off the massive 2011 Japan tsunami — there is indeed a subduction zone capable of creating tsunamis near the East Coast. In the northeast Caribbean, the area called the Puerto Rico trench features a subduction zone.
When the 2004 Indian Ocean tsunami hit, ten Brinks' group received funding from the U.S. government to study the tsunami potential of the Puerto Rico trench. Although its work is still ongoing, his group has found that much of the fault doesn't appear capable of creating an earthquake and tsunami large enough to cause big problems for the East Coast. But a tsunami originating there could cause significant destruction in the Caribbean. [Album: Monster Waves]
University of Puerto Rico researcher Zamara Fuentes, who isn't involved in ten Brinks' research, said one quake in this region in 1918 created a tsunami that killed 116 people on Puerto Rico. Fuentes studies sediment cores around the Caribbean to look for evidence of past tsunamis. Based on historical records, the USGS says 27 tsunamis in the Caribbean have caused fatalities and extensive damage since the 16th century.