Caribbean region in earthquake and tsunami risk
In a new study, geologists Jian Lin of the Woods Hole Oceanographic Institution (WHOI) and Uri Ten Brink of the US Geological Survey reported a heightened earthquake risk of the Septentrional fault zone, which cuts through the highly populated region in the Dominican Republic. Their findings were published inthe Journal of Geophysical Research from the American Geophysical Union last December. With nearly 20 million people now living in this tourist regionand a major earthquake occurring on average every 50 years, scientists say it is not a question of if it will happen but when.The most recent major earthquake, a magnitude 8.1 in Richter scalein 1946, resulted in a tsunami that killed a reported 1,600 people.
"According to our research and based on the historical records,the probability of a major earthquake that can cause tsunami in Caribbean region is very,very high," Lin told Xinhua. "This disaster, if it happens nowadays, will certainly kill much more people than it did half a century ago."
The geologically active offshore Puerto Rico and Hispaniola trenches are capable of producing earthquakes over magnitude 7.5. The Indonesian earthquake on Dec. 26 which generated a tsunami that killed an estimated 150,000 people, came from a fault of similar structure, but was a magnitude 9.0. Lin and Brink studied the geology of the northern Caribbean plate boundary, looked at historical earthquake data in the region,and used three-dimensional models to calculate the stress changes in and near the trenches after each earthquake. They say stress has increased for the Hispaniola area, and that the potential threat of earthquakes and resulting possible tsunamis from the Puerto Rico and Hispaniola trenches is real and should be taken seriously.
Lin, a senior scientist and a marine geophysicist with the WHOI, said that each time an earthquake occurs on the offshore Puerto Rico and Hispaniola trenches, it adds stress to the Septentrional fault zone on Hispaniola. Since the fault is in a highly populated region and is capable of generating magnitude 7.7-7.9 earthquakes, the public should be educated about the risk. In addition to establishing warning systems and informing the public about the risk, scientists call for improved documentation of prior earthquake and tsunami events and better estimates of future threats from the Puerto Rico and Hispaniola trenches through underwater studies. In the past 500 years, a dozen major earthquakes of magnitude 7.0 or greater have occurred in the Caribbean near Puerto Rico, the US Virgin Islands and the island of Hispaniola, shared by Haiti and the Dominican Republic, and several have generated tsunamis, Lin said. Enditem