CARIBBEAN:
Keeping a Look-Out for Tsunamis
Patricia Grogg

HAVANA,  (IPS) - Fear of a tragedy similar to the one caused in Asia by the tidal wave in the Indian Ocean just after Christmas in 2004 has alarms buzzing in the Caribbean, where moves are afoot to establish an Early Warning System (EWS) for tsunamis.

Scientists working on the project are convinced that the occurrence of tsunamis in the region is entirely possible, and they emphasise the importance of complementary prevention and risk mitigation programmes alongside the EWS.

"As well as investing in satellite systems, buoys and probes, people must be trained and educated. Prevention is essential to reduce the risk of a disaster," Enrique Arango, an expert at the Cuban National Seismological Research Centre (CENAIS), told IPS.

All over the world, statistics indicate that natural phenomena are causing increasingly large losses of human lives and material damages, owing to the increase of population density in coastal areas, and the social and economic vulnerability of many island territories.

Arango warned that "a technocratic view of the problem could lead to the conclusion that a disaster can be avoided simply by implementing an EWS," which is a network of seismic and wave sensors on land and sea, linked by radio to a satellite that transmits continuously to a monitoring centre.

This centre issues an automatic alert if an earthquake capable of generating tidal waves is detected, or if an unusual wave pattern signals the creation of a tsunami.

"The problem is not merely to issue a tsunami warning. Risk evaluation and risk management must be worked on in parallel, which means diagnosing and eliminating existing vulnerabilities, and not creating new ones in the danger areas," Arango said.

A regional alert system needs to include seismological, oceanographic and civil defence services, interconnected in real time. The population must be educated and prepared, and because of the speed of the tidal wave, it must be taken into account that places close to the epicentre will receive their warning too late.

More than 220,000 people died in Asia and parts of Africa in late December 2004 as a result of the tsunami, a Japanese word for the enormous waves formed as a result of undersea earthquakes or volcanic eruptions.

The tsunami was produced by an earthquake registering a magnitude of nine on the Richter scale, with its epicentre close to the Indonesian island of Sumatra. After the tsunami, many islands and coastal countries began to study the risks and develop local prevention and contingency programmes.

But implementing a regional EWS will require more resources, and will depend above all on the good will and real capacity for participation of many countries and institutions with disparate interests.

"To a certain extent this makes it difficult to create a regional EWS in a short time that satisfies all countries equally," said Arango, who said it was important for Cuba to be part of this network, even though the main threats to his country were really hurricanes or earthquakes.

The expert said that CENAIS has a network of seismological stations with technical equipment capable of detecting earthquakes in the Caribbean and along the Pacific coast of Central America, which it is willing to share with the planned EWS.

Since the 15th century there have been between 30 and 40 tsunamis in the Caribbean, caused by undersea earthquakes, landslides resulting from the quakes, or volcanic eruptions in the Lesser Antilles.

In Arango's opinion, the data indicate that there is a real risk of new tidal waves. One of the danger points is Kick-'em-Jenny, an active underwater volcano about eight kilometres from the small island of Grenada, which has erupted more than 10 times since its discovery in 1939.

"The islands located on the arc of the Lesser Antilles are exposed to the greatest danger, because the tectonic process at work there is subduction, which is when one tectonic plate slides under the edge of another. That's when the strongest earthquakes happen, and they frequently generate tsunamis," Arango said.

The expert said that this process is similar to that which occurs in the Indian Ocean, and in the "Ring of Fire" bordering the Pacific coast from Asia to America, where a large number of tectonic plates are undergoing subduction and other movements, and there is high seismic activity.

Subduction leads to the formation and development of active volcanoes, which can erupt and cause tsunamis, like the eruption of Mont Pelée on the island of Martinique in 1902, he said.

The tsunami risk for Central American countries is far greater on the Pacific coast than on their Caribbean shores. One of the worst tsunamis was in Nicaragua in 1992, which caused the deaths of 170 people.

The southeast of Cuba is prone to earthquakes because of its proximity to the contact zone between the North American plate, to which the island of Cuba belongs, and the Gonave microplate, located between Cuba, Jamaica and Haiti. Along the fault line known as the Cuban Margin (falla Oriente), these two plates slide horizontally past each other at a rate of 20 mm a year.

However, this sliding type of movement is very unlikely to cause earthquakes of high enough magnitude to generate a tsunami that would be catastrophic for Cuba or any nearby country.

The most likely source of tidal waves produced by an earthquake near Cuba is the subduction zone located north of the islands of Hispaniola and Puerto Rico.

In mid-March, Venezuela played host to the second meeting of the Intergovernmental Coordination Group for the Tsunami and Other Coastal Hazards Warning System for the Caribbean and Adjacent Regions (ICG-C).

This meeting, that followed a previous conference in Barbados in January 2006, decided to create an information centre and to study the feasibility of making Venezuela or Puerto Rico the headquarters of the EWS.

The vast majority of Latin American and Caribbean countries with a coastline do not have advanced systems for measuring earthquakes on the sea bed. They are practically entirely dependent on the Pacific Tsunami Warning System, based in Hawaii.