New York- A tsunami triggered by a volcanic eruption on an island off the coast of Africa could result in mountainous waves up to 75 feet high crashing into New York and other East Coast cities, scientists are warning.

A 12-mile-wide chunk of the Cumbre Vieja volcano on the Canary Islands rattled loose during a previous eruption and is at risk of smashing into the Atlantic Ocean, triggering what could be one of the largest tidal waves in recorded history, researchers told Britain’s Royal Institution earlier this month.

“It’s not a matter of if, but when,” said Prof. Bill McGuire, director of the Benfield Grieg Hazard Research Centre at University College in London.

In the deep seas, a tidal wave created by such a landslide would travel at the speed of a jetliner – up to 600 mph – meaning U.S. coastal cities would have eight to 10 hours of warning before a mountainous wall of water reared up on its shores, McGuire said.

“Once it’s happened, it would be extremely difficult to evacuate all those people out in time,” McGuire told the Daily News.

The Cumbre Vieja volcano on the island of La Palma has been the most active volcano on the Canary Islands. A 1949 eruption shook loose the western flank of the 6,300-foot volcano that is now at risk of tumbling into the sea. The last eruption happened in 1971 on the southern tip of the island.

A similar catastrophe was responsible for the death of more than 2,000 people in Papua New Guinea on July 17, 1998, when a magnitude 7 earthquake triggered a landslide that in turn touched off a 50-foot-tall tsunami.

Other experts agreed that Cumbre Vieja could trigger a similar event.

“If you peel off a side of a volcano and let it slide into the deep ocean, yes, it’s going to generate a tidal wave. And from that location it will travel to the U.S.,” said John Mutter, a seismologist at Columbia University’s Lamont-Doherty Earth Observatory.

But without close monitoring of the volcano, it’s impossible to predict whether the next eruption will be next week or decades away, Mutter said.

“They are seldom periodic. You’re not going to be able to set your clock by it,” he said.

If it does happen, however, computer models have shown the tidal wave could pack a devastating punch, said Philip Watts, a private engineer in Long Beach, Calif., who has helped researchers estimate the impact of tsunamis.

“The good news is this wave might break while traveling over the continental shelf and lose a lot of its energy by the time it reaches the shoreline,” Watts said. “But there will still be places where it will hit considerably hard.”

McGuire noted that such a tsunami could travel several miles inland, wreaking havoc on all in its path.

“The waves would be hitting all along the East Coast of North America,” McGuire said. For every 300 feet of shoreline, the waves would dump “the same amount of energy as generated by the collapse of the World Trade Center.

“We need to get advanced warning because in the Eastern U.S. and the Caribbean, we have to get an enormous number of people away from the coastline,” he said.