The first sign of a tsunami is not always the sea receding from the shoreline. Roy Watlington, professor of physics at the University of the Virgin Islands, shared this and other helpful tips regarding earthquakes and tsunamis at his Tuesday evening, January 8, presentation at the St. John Historical Society’s January meeting at the Nazareth Lutheran Church.
Tsunamis are primarily a result of earthquakes, which occur when energy is released due to friction between two of the earth’s plates. The Caribbean has its own plate, defined by Caribbean islands to the east and South American volcanoes to the west. The Caribbean plate is “very aggressive,” according to Watlington.
“We get our share of earthquakes,” he said.
1867 Quake, Tsunami
Recent local earthquake history shows several quakes, including a magnitude 5.9 on November 29 and a 5.4 on December 18 of last year. Earthquakes of less than 6.2 are not expected to directly generate tsunamis, according to the professor.
The Virgin Islands has, however, experienced an earthquake of a high magnitude and a resulting tsunami. On November 2, 1867, the V.I. was recovering from an October 29 hurricane which claimed the lives of nearly 600 island residents. At 2:50 p.m. on November 2, a quake thought to be between 7.2 and 7.5 in magnitude rattled the Virgin Islands, and just five minutes later, a wall of water traveling nearly 221 miles per hour slammed into the surrounding islands.
The wave came in and out several times leaving vessels beached, including the USS Monongahela, a ship anchored in Frederiksted that assisted in the movement of diplomats who were working on the possible purchase of the then-Danish West Indies by the U.S.
“After the tsunami, aftershocks continued keeping the level of fear high,” said Watlington. “Sailors helped to rebuild Frederiksted using ship’s sails to make tents, because people were afraid to sleep in what houses were left.”
The 1867 tsunami also struck Coral Bay, as documented by a member of the Moravian church. People were “startled” and “driven out of their houses,” according to the account.
Greater Loss of Life Today
“The sea struck terror into many hearts,” according to the Moravian’s account, which is published in Watlington’s book, “Disaster and Disruption in 1867.”
Just 20 people died in the quake and tsunami, however should the same event occur today, the loss of life would be much greater, according to Watlington.
“Today, we have cruise ship passengers and we are a large regional exporter of petroleum products,” he said. “We have a shoreline industry, where public spaces and habitation raise concern. During the business day, thousands of Virgin Islanders join visitors in populating at-risk shorelines, where back then, many lived and worked inland and upland.”
In addition to the risk for greater loss of life, a devastating event such as a tsunami would likely cause significant damage to the local economy. In 1996, the general fund was down 8.1 percent due to Hurricanes Marilyn and Bertha.
The V.I. experiences earthquakes quite often, but most are of a low magnitude. The frequency of earthquakes could mean the Caribbean plate is letting off energy slowly — or, it could imply the “next big one is coming,” explained Watlington.
While a warning system for earthquakes is not feasible, tsunami warning systems are being set up across the globe, an effort that picked up steam following the devastating December 2004 tsunami in Indonesia.
How to Be Tsunami Ready
Deep-ocean Assessment and Reporting of Tsunamis buoys have been deployed in the Caribbean, however the buoys’ current placement does not much help the V.I., as they are not located in the area from which the islands can most expect a tsunami to originate.
Currently, the Alaska Tsunami Warning System has jurisdiction over the Virgin Islands, however a proposed Caribbean Tsunami Warning Center would be responsible and accountable locally 24/7, explained Watlington.
“Spontaneous responsiveness will save people’s lives,” said the professor. “If you feel an earthquake strong enough to knock you off balance, go upland. If you seem foolish running, at least you’ll be alive and foolish.”
Watlington strongly advises residents not to run down to the shoreline to observe the sea being drawn out before a tsunami, as this phenomenon only occurs in 50 percent of tsunamis. The other 50 percent of the time, the wave will make landfall first and then retreat.
There are several steps the V.I. can undertake to become “Tsunami Ready” — a National Weather Service program being considered by the V.I. Territorial Emergency Management Agency which helps communities reduce the potential for disastrous tsunami-related consequences, including:
– Implement a response system and escape routes
– Develop a worst-case scenario plan for cruise ships and tankers
– Relocate schools and densely occupied public buildings from sea level
Local earthquake activity can be monitored with almost immediate results at both the Puerto Rico Seismic Network, redsismica.uprm.edu/english/ and the U.S. Geological Survey, earthquake.usgs.gov.