The April 12 quake, which registered a magnitude of 4.0, wasn’t particularly strong or unusual, but its precise location was intriguing, he says. Though “no one but for a few lobsters felt anything,” he says, the earthquake occurred along the edge of the continental shelf, a setting similar to the Grand Banks earthquake of 1929, a temblor measuring 7.2 in magnitude that was felt as far away as New York City. That quake created what is called a “submarine slide.” Forty-eight cubic miles of sediment from the continental shelf sheared off, and the tsunami created by this displacement claimed 29 lives in Newfoundland.

“I think the possibility that a similarly large earthquake could occur off the East Coast of the U.S. has to be considered,” says Canadian seismologist Allison Bent. But the question is whether such an earthquake would produce a tsunami. The majority of earthquakes in the region are “strike-slip,” meaning the movement is horizontal. These, she explains, generally don’t produce tsunamis. The probability of a submarine slide is low, but, she adds, “not zero.”

Even if such an event occurred, there would be no time for a meaningful warning, says George Pararas-Carayannis, president of the Tsunami Society International.