Monday, January 18, 2010

Caribbean at risk of more large quakes like Haiti mega earthquake: Report


London: Earthquake experts have warned that the devastating quake that struck Haiti on January 12 could be the first of several in the region, which means the region is at risk of more large tremblors.

According to a report in New Scientist, historical records suggest that not all the energy that has built up in the faults running through the Caribbean region was released in the Haiti quake.

Their fear is that enough energy remains in the fault system to trigger another earthquake of the same scale as the one on January 12.

The last time Haiti was struck by earthquakes of this scale was in 1751 and 1770, when three large earthquakes hit within the space of 20 years.

They ruptured the same fault segment as the one that slipped on Jan. 12, as well as segments lying further to the east, in Haiti and the neighbouring Dominican Republic.

"Last time round there was a sequence of earthquakes," said Uri ten Brink, an expert on earthquakes in the region from the US Geological Survey in Woods Hole, Massachusetts.

"I'm worried, as we might expect the eastern side of the fault to rupture next," according to other geologists.

"Stress transfer along the fault is likely to trigger a chain of quakes," said Bill McGuire from University College London.

Another, larger earthquake could affect surrounding nations as well.

The fault that was responsible for the Haiti quake extends west through Jamaica. Another runs parallel to it in the north, along the southern edge of Cuba and the northern side of Haiti and the Dominican Republic.

Historical records suggest that both these faults produce large and destructive earthquakes every few centuries.

"They are dangerous especially when large population centres like Port-au-Prince, Kingston in Jamaica or Santiago in the Dominican Republic are so close to them," said Paul Mann from the University of Texas at Austin.

The region harbours a third fault to the east, which is a further cause for concern.

Measurements over several decades show that the sum of all earthquakes that strike on "splinter faults" on the Caribbean plate have accounted for around half of the energy associated with this movement, leaving the other half stored up in the system.

McGuire and his colleagues are concerned that much of the stress may be accumulating on the undersea thrust fault to the east.

If that stress were to be released on the submarine fault, it could trigger a catastrophic tsunami of the scale of the 26 December 2004 Indian Ocean disaster.

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