Eastern Caribbean Earthquakes
The Eastern Caribbean is an example of an island arc system formed at a convergent plate boundary (more specifically, at a subduction zone, where two tectonic plates meet and the denser plate is forced beneath the lighter plate). This is the main cause of the volcanic and seismic activity in the Eastern Caribbean.
Most of the earthquakes occurring in the Eastern Caribbean are either tectonic or volcanic in origin. Tectonic earthquakes are generated when plates move as accumulated strain energy is released. Volcanic earthquakes are generated by the movement of magma within the lithosphere (rock). Since magma is less dense than the surrounding rock, it rises to the surface, breaking the rock as it moves, thereby generating earthquakes. In fact, more than 75% of the world’s earthquakes occur at convergent plate boundaries. The countries of the Eastern Caribbean are therefore, highly susceptible to earthquakes.
One striking example is that of Trinidad in 1766; although the population was small and the economy minuscule, the effects of the earthquake were devastating enough to cause the inhabitants to petition the King of Spain to allow settlement from other, non-Spanish, Caribbean islands. Prior to this event, there was another major earthquake in Jamaica (N.W Caribbean) in 1692 which resulted in the death of over 2,000 persons and destroyed 90% of the then capital, Port Royal. In fact, it is clear that such major earthquakes are likely to cause even more damage if they were to occur now or in the future because of increasing population sizes coupled with large-scale poorly planned urban centres and unregulated construction. A clear example of this was Haiti’s 2010 magnitude 7.0 earthquake which devastated Port-au-Prince and resulted in the deaths of more than 200,000 persons.
Although there are considerable variations in the level of activity, no island in the region is completely free from the threat of earthquakes.
How are earthquakes and volcanoes formed in the Eastern Caribbean
Actual earthquake disasters in the Eastern Caribbean over the past 300 years
|Year||Location and Magnitude||Effects|
|1690||Close to Antigua. M > 8||Considerable destruction in Antigua, St. Kitts, Nevis, Montserrat. Casualties and economic cost unknown. Read an eyewitness account of this event. Please note that the document is written in old English.|
|1766||Between Trinidad and Venezuela. M > 8||Total destruction of all masonry buildings in Trinidad. Complete destruction of the economy. Casualties and cost unknown.|
|1839||Close to Martinique. M ~ 6.5||About 400 dead. Severe damage in St. Pierre and almost total destruction of Fort-de-France.|
|1843||Between Antigua and Guadeloupe||Considerable destruction in all islands from Saba to Dominica. Nearly 2,000 deaths, mainly in Guadeloupe. Considerable economic disruption in all islands. Read extensive eyewitness accounts of this earthquake.|
Near Misses during the period 1900 – Present
|Year||Location and Magnitude||Effects|
|1906||M > 7 North-west of St. Lucia.||Severe damage in Saint Lucia and Martinique. No deaths.|
|1918||M = 6½ North-west of Trinidad.||Most masonry buildings in Port of Spain destroyed.|
|1953||M = 7¾Depth 175 km North-east of St.Lucia||Felt at damaging intensities in Saint Lucia, Barbados and St. Vincent. Little serious damage because there were few large buildings at the time. Since then there has been very large-scale development of multi-storey hotels in all islands, particularly in Saint Lucia within 50 km of the epicentre.|
|1954||M = 6½ North of Trinidad||In Port of Spain good quality masonry structures collapsed. The number of similar structures has increased since then by a factor of more than ten. There has been considerable unplanned development on reclaimed land close to the epicentre and the population has doubled. A repeat of this event would be disastrous. An increase in magnitude by one unit would be catastrophic. The effect of a repeat of the 1766 earthquake is unimaginable.|
|1974||North-West of Antigua||Damage in all nearby islands. Increase in vulnerability.|
|2004||M=6.3 Northeast of Dominica||Felt throughout Dominica as well as Guadeloupe, Montserrat, St. Maarten, Antigua, Nevis and St. Vincent. Structural damage in Dominica. One death in Guadeloupe.|
|2007||M=7.3 North of Martinique||Felt over an area between Guyana in the south, Colombia and Puerto Rico in the west and Anguilla in the north. Significant damage was restricted to the immediate vicinity of the earthquake. In Martinique, one person suffered a heart attack and died, one building collapsed and one hospital and some schools reported other less severe damage.|
|2018||M=6.9 Gulf of Paria||Strongly felt throughout Trinidad and Tobago, with felt reports coming from as far north as Dominica and as far south as Suriname. Shaking from the earthquake, in Trinidad and Tobago, was reported to have persisted for periods in the range 45-90 s. there was significant ground failure in a landslide prone farming area in Los Iros, Trinidad.|
Map of earthquakes greater than magnitude 6.9 (1500-1900)
Map of earthquakes greater than magnitude 5.0 (1900-2019/07)
This information clearly indicates that Eastern Caribbean earthquake activity carried on unchanged through the 20th and 21st centuries. During the 20th and 21st centuries, the vulnerability of all islands to major earthquakes increased enormously because of continuous population growth and changes in building and land use practices. At the beginning of the 20th century, most buildings in the region were made of wood or similar materials, which have a high intrinsic earthquake resistance. High-rise buildings and the use of reclaimed land were also uncommon. However, the current situation on every island is such that most buildings are made of masonry or concrete and there are numerous high-rise buildings, of which a high proportion are built in areas which were under the sea less than a century ago, i.e.reclaimed land.