After the recent devastating loss of life from the DecemberIndonesian tsunami, geophysicists are searching for otherareas where the same kind of disaster may be lurking due topotential underwater earthquake activity. Now they saythere's a real danger that the Caribbean will be next.
Scientists say that several natural phenomena could triggergiant tsunamis, with effects felt in the islands of theGreater and Lesser Antilles and along the east and Gulfcoasts of the United States. These areas, which wererelatively sparsely populated when the last waves hit, nowhave large populations.
Nancy Grindlay and Meghan Hearne of the University of NorthCarolina Wilmington and Paul Mann of the University of Texasat Austin focus on one major source of past tsunamis in theregion: movement along the boundary between the NorthAmerican and Caribbean tectonic plates.
Writing in the March 22 issue of Eos, the newspaper of theAmerican Geophysical Union, they say that at least 10significant tsunamis have been documented in the northernCaribbean since 1492, six of which are known to haveresulted in loss of life. All 10 were triggered by movementalong this plate boundary, which lies along the north coastof Hispaniola (Haiti and the Dominican Republic) and extendssome 3,200 kilometers [2,000 miles] from Central America tothe Lesser Antilles.
Previous tsunamis destroyed Port Royal, Jamaica, in 1692,killed at least 10 Jamaicans on the island's south coast in1780, and ravaged the north coast of Hispaniola and theVirgin Islands in 1842. The most recent of the destructivenorthern Caribbean tsunami occurred in 1946 and wastriggered by a magnitude 8.1 earthquake in the DominicanRepublic. It killed around 1,800 people.
The researchers estimate that with increased populations,especially in coastal areas, some 35.5 million people arenow at risk should another strong tsunami hit the northernCaribbean. They note that in addition to their own studiesof fault lines along the North American and Caribbean plateboundary, other researchers have studied the risk to thenorthern Caribbean from submarine landslides, both in theregion and as far away as the Canary Islands. In thepre-1492 period, tsunamis greater than any in the past 500years may have occurred, the scientists say, based on theirstudy of underwater landslides off the north coast of PuertoRico.
Grindlay and her colleagues are planning to visit the regionlater this month to investigate possible linkages betweengroundwater flow from Puerto Rico and underwater seeps inareas where land has subsided. Such flows, or fluxes, couldcontribute to small landslides that might trigger tsunamis.In the future, they hope to drill into the ocean bed todetermine when and how often land had collapsed in theprehistoric era.
"The recent devastating tsunami in the Indian Ocean hasraised public awareness of tsunami hazard and the need forearly warning systems in high risk areas such as theCaribbean," Grindlay said in a statement. "An Intra AmericasSea Tsunami Warning Project proposal has been approved bythe Intergovernmental Oceanographic Commission, and meetingsto plan implementation are scheduled for this spring andsummer."
The research was funded by the National Science Foundationand the University of Puerto Rico SeaGrant program.
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