What Causes Tsunamis?


Earthquake-induced movements of the ocean floor most often generate tsunamis. Landslides, volcanic eruptions and even meteorites can also generate a tsunami. If a major earthquake is felt, a tsunami could reach the beach in a few minutes, even before a warning is issued. Areas at greatest risk are less than 25 feet above sea level and within one mile of the shoreline. Most deaths caused by a tsunami are because of drowning.  Associated risks include flooding, contamination of drinking water, fires from ruptured tanks or gas lines, and loss of vital community infrastructure (police, fire and medical facilities).


The 2004 Indian Ocean tsunami could rank as the most devastating on record. More than 200,000 people lost their lives, many of them washed out to sea. The most damaging tsunami on record before 2004 was the one that killed an estimated 40,000 people in 1782 following an earthquake in the South China Sea.

Tsunamis in the Caribbean

In the past 500 years there have been ten confirmed earthquake-generated tsunamis in the Caribbean Basin, with four causing fatalities. An estimated 350 people in the Caribbean were killed by these events.

All known sources capable of causing tsunamis occur within striking distance of the Eastern Caribbean, and there are also distant sources across the Atlantic. Since the islands lie in an area of relatively high earthquake activity for the Caribbean, the most likely tsunamis to affect the region are those which can be triggered by shallow earthquakes (<50km depth), in the region, greater than magnitude 6.5. The recurrence rate for tsunamis in the Caribbean is approximately one destructive tsunami per century for local earthquakes and one destructive tsunami per 200 years for distant earthquakes.

Currently, there is no tsunami warning system for the Caribbean, however, an interim arrangement exists with the Pacific Tsunami Warning Centre. Scientists at the Seismic Research Unit at the University of the West Indies St. Augustine campus in Trinidad and Tobago, together with other regional agencies such as the Caribbean Disaster Emergency Management Agency (CDEMA), are in the process of developing a warning system but it may be several years before this is complete.


Contributing sources Jamaican
Office of Disaster Preparedness and Emergency Management
CDEMA