Can a Tsunami Strike the Atlantic Coast?

Can a tsunami strike the coast of New Jersey, North Carolina, or Florida? The question crossed my mind as I was doing research for my action/adventure novel TSUNAMI, even though the book is set in the Pacific.

The answer is yes, a tsunami hitting the Atlantic Coast is possible, but much less likely than one striking Alaska, Hawaii, or the Pacific Northwest. When it comes to the kinds of natural events that start tsunamis -- undersea earthquakes, submarine landslides, and volcano eruptions -- the Atlantic is a much tamer ocean than the Pacific. The Pacific basin is encircled by the notorious Ring of Fire with its hundreds of active volcanoes and dozens of dangerous, earthquake-prone subduction zones. The Atlantic has far fewer geological areas capable of posing a genuine tsunami threat. But there are some, and they should be taken seriously.

The one most talked about is the Cumbre Vieja volcano in the Canary Islands, 3000 miles from Boston and 3700 miles from Miami. In 1949, a flank of the volcano split off, creating a 3-ft. rift, the flank sliding down 3 feet toward the ocean before it stabilized. Earthquakes and a buildup of pressure inside the volcano were associated with the event. The concern is that another earthquake or eruption could dislodge the entire flank and send as much as 300 cubic miles of debris plunging into the ocean. One school of thought suggests that such a monster landslide would start a tsunami capable of reaching the eastern seaboard of the United States 5 or 6 hours later.

Even if such an event were to happen, many geologists dispute the notion that it would send a killer tsunami smashing into the East Coast of the U.S. The height of the initial wave would be enormous, but the length between waves would be relatively short, meaning its ability to maintain its energy while travelling long distances would be minimized. Undersea earthquake-generated tsunamis typically have long wavelengths, or distance between waves in the train, and can travel long distances without significant loss of energy. In contrast, landslide-initiated tsunamis tend to have short wavelengths and are usually confined to local areas where they can be highly destructive. In 1883, the Krakatau eruption dumped millions of tons of debris into the ocean and started a 135-ft. tsunami that did incredible damage to Sumatra and neighboring islands but did not affect other areas.

To sum it up, there are two points of view. One maintains the collapse of a chunk of Cumbre Vieja into the ocean could endanger the Atlantic Coast of the U.S. with a major tsunami, while the other view holds that the dynamics of wave formation make such a result unlikely.

The only true subduction zone close to the East Coast is the Puerto Rico Trench, which runs for 1000 miles from Puerto Rico eastward past the Lesser Antilles and out into the Atlantic Ocean. The deepest point in the Atlantic at 28,200 feet lies in The Puerto Rico Trench. Along this trench, the Caribbean tectonic plate is subducting, or sliding under, the North American Plate. This is not as large or active a subduction zone as most of those in the Pacific, but undersea earthquakes have occurred there, resulting in tsunamis that affected the islands in the Caribbean. The last tsunami in the area happened in 1918 when 32 people died in Puerto Rico and the Virgin Islands.

Mt. Pelee on Martinique is one of several active volcanoes in the Lesser Antilles arc. The 1902 eruption of Mt. Pelee is one of the largest on record. It is possible that volcanic debris from future eruptions could crash into the ocean and start a localized tsunami.

Submarine landslides at the edge of the continental shelf along the Atlantic Seaboard might also start tsunamis that could impact coastal cities. In 1929, a 7.2 magnitude earthquake off Newfoundland started an undersea landslide down the continental shelf. The resulting tsunami swept ashore and killed 8 people.

The Atlantic Tsunami Warning System was installed in 2006, comprising five Deep Ocean Assessment and Reporting of Tsunami (acronym DART) buoy stations. Single stations are located off Charleston, Miami, and New Orleans. Two are positioned off Puerto Rico near the Puerto Rico Trench. All provide real time detection of undersea disturbances capable of starting tsunamis that could impact the Atlantic, Caribbean, and Gulf Coasts. Plans call for the addition of at least two more DART stations.

If you live in a low-lying area on the Atlantic Coast, be aware that a tsunami is always a possibility, and be prepared to evacuate on a moment's notice as directed by local authorities.