Underwater faults make V.I. susceptible to tsunamis
Published: October 6, 2012
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Situated in a seismically volatile region, the Virgin Islands is vulnerable to tsunamis.
With underwater fault lines running between St. Thomas and St. Croix and also north of St. Thomas and Puerto Rico, the threat of a rare but deadly tsunami in the area is real, emergency managers say.
Other geological activity - volcanic activity and underwater landslides - in the greater Caribbean region also have the potential to generate tsunamis.
Tsunamis - massive waves created by a sudden large disturbance of ocean water, most often caused by an earthquake forcing an uplift in the sea floor - have struck the territory before.
In 1867, a series of tsunamis hit the Virgin Islands when a magnitude 7.5 earthquake shook the seabed between St. Thomas and St. Croix. Within minutes, the massive waves rushed ashore on both islands, killing a number of people.
Another deadly tsunami struck Puerto Rico in 1918 after an earthquake, killing dozens and doing extensive damage to that island's west end.
In both the 1867 and the 1918 tsunamis, the waves slammed into shorelines rapidly - within minutes of the earthquakes that generated them.
Although dramatic, tsunamis also are rare, and not all earthquakes under the ocean floor - even strong ones - generate tsunamis.
The territory experiences minor earthquakes on a regular basis, although many are not felt.
On Friday evening, VITEMA's VI-Alert System showed a list of 23 alerts it had issued on earthquakes in the Virgin Islands and Puerto Rico regions for the day. They ranged from a magnitude 2.6 to a magnitude 4.2.
Scientists who have spoken to The Daily News in the past recommended that in situations where there are not tsunami warning sirens, if you feel a strong earthquake - strong enough to knock you down and make it difficult to stand - and after 20 seconds, the ground still is shaking, that is a good indicator that the earthquake is close enough and strong enough to generate a tsunami.
In that situation, they recommend that people not wait for a tsunami warning, but move to higher ground as soon as is feasible.