" Tsunamis and the Eastern Caribbean "
THE UNIVERSITY OF THE WEST INDIES, SEISMIC RESEARCH UNIT
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St.
Augustine, Trinidad and Tobago, W.I. --December 28th, 2004
A
tsunami is an ocean wave or series of waves caused by an abrupt disturbance
of the ocean floor that displaces a large mass of water. Tsunamis are
caused either by tectonic earthquakes (earthquakes generated by the movement
of plates) occurring both in and out of the region, or volcanic events
such as dome collapses/landslides or the eruption of submarine volcanoes.
While it is possible for the region to be hit by a tsunami such as the
one recently experienced in Asia, scientists currently believe that there
is a very low probability of this phenomenon occurring.
In
the past 500 years there have been four earthquake-generated tsunamis
to affect the Caribbean, none of which was more than 1m in amplitude.
In total about 350 people were killed by these events. These tsunamis
occurred as a result of earthquakes in:
- May,
1842, Haiti – An intense local tsunami was believed to have killed
up to 200 people in the town of Port-de-Paix
-
November, 1867, Virgin Islands – Death toll about 20, all in the
Virgin Islands
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October, 1918, Puerto Rico – Death toll about 29 in Puerto Rico
-
August, 1946, Dominican Republic – An intense local tsunami which
mainly affected the town of Matanzas where up to 100 people were killed
In
July 2003, a major dome collapse from the Soufriere Hills Volcano in Montserrat
caused a tsunami that was experienced in Guadeloupe at about 1m high and
in some parts of Montserrat at 4m in amplitude.
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While
recent events in Asia have caused much concern over the Caribbean’s
vulnerability to tsunamis, it is important to note that all oceans can
experience tsunamis but there are more large, destructive tsunamis in
the Pacific Ocean because of the many major earthquakes along the margins
of the Pacific Ocean and also because dip-slip earthquakes (which involve
vertical rather than lateral ground motion) are more common in the Pacific
than elsewhere. As a result of the immediacy of the tsunami hazard to
countries in the Pacific, there is currently a tsunami early warning system
in that region. There is no tsunami warning system in the Caribbean.
The
first sign of an approaching tsunami is usually a significant retreat
of the sea. As a result, the trailing waves pile on top of the waves in
front of them, thereby significantly increasing the height of the wave
before hitting the shore. Although a tsunami advances much slower as it
approaches land, its momentum is powerful enough to cause severe destruction.
If you are close to the sea and the water retreats by an abnormal amount,
move to high ground at once.
While
it is possible that the region could be affected by earthquake-generated
tsunamis, scientists currently believe that the more immediate threats
posed by earthquake hazards such as collapsing buildings, falling electricity
lines, ruptured gas lines, rock slides and/or landslides on mountains
and hillsides (as recently witnessed in Dominica, Trinidad, the British
Virgin Islands and the Cayman Islands) are more of a present danger to
the region. Greater focus should, therefore, be placed on ensuring that
effective public education programmes are undertaken to sensitize the
public to these hazards and serious consideration should be given to constructing
sound earthquake-resistant buildings.
For
updates on these and other geologic events occurring in the region please
visit the Seismic Research Unit’s website at www.uwiseismic.com.
Based at the University of the West Indies in St. Augustine Trinidad,
the Seismic Research Unit is the agency responsible for monitoring earthquakes
and volcanoes throughout the English-speaking Eastern Caribbean.
For more info, log on to www.uwiseismic.com
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