Dear Editor,
The beautiful Caribbean is one of the most geologically active spots on earth and seismic activities and processes over the ages have helped raise and sculpt the islands of the Caribbean.
Seismographers believe the earthquake which devastated Haiti two weeks ago is not the last that will be experienced in the region. Experts say historical records suggest there is still a lot of energy remaining in the faults running through the Caribbean after the calamitous Haiti earthquake. According to these scientists, “enough energy remains in the fault system to trigger another earthquake of the same scale” as Haiti’s.
More than 200 years ago between 1751 and 1770, Haiti and parts of the Dominican Republic were devastated by three earthquakes of similar magnitude as this most recent one, according to Uri ten Brink, earthquake expert at the US Geological Survey (USGS). ten Brink noted the sequence of the earthquakes during that 20-year period which ruptured the same fault as the Haitian earthquake on January 12 last. He is worried that the eastern side of the fault may rupture next. Bill McGuire of the University of London concurred that “stress transfer along the fault is likely to trigger a chain of quakes.”
The experts noted that “another large earthquake could affect surrounding nations as well. The fault that was responsible for the Haitian 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 both these faults produce large and destructive earthquakes every few centuries.” These faults are reported to be dangerously located near to densely populated urban centres such as Kingston, Port-au-Prince and Santiago, Dominican Republic.
In 2008, Paul Mann of the University of Texas at Austin forecast a major quake in the region.
Even worse, there is a third fault lying underwater, unlike the others which are located on land, according to Mann. He said this fault is located “where the Atlantic Ocean plate dives underneath the Caribbean plate, creating the Caribbean Island chain: it is a submarine thrust fault, like the one that caused the Indian Ocean earthquake and tsunami on 26 December, 2004” in which hundreds of thousands of people perished.
According to McGuire “satellite measurements show that the Caribbean plate is moving east over the Atlantic plate at around two centimetres per year. Measurements over several decades show that the sum of all earthquakes that strike on ‘splinter faults’ on the Caribbean plate,” like Haiti’s most recent, “have accounted for around half of the energy associated with this movement, leaving the other half stored up in the system. Some of the remainder may be accommodated by slow creep along the region’s faults.” McGuire and his colleagues at the University of London are concerned that “much of the stress may be accumulating on the undersea thrust fault to the east.”
They have since concluded that “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.”
In 2008, McGuire released a report warning of this impending danger. He said the entire Caribbean, Central America, the US Gulf coast and the north coast of South America would be at risk from such a tsunami.
Recent geological measurements indicate stress is building in the section of submarine fault between the easternmost Dominican Republic and the island of Guadeloupe. Large earthquakes of magnitude 8.5 to 9.0 (more powerful than Haiti’s 7.0) could rupture the entire 1,000-kilometre length of the fault, according to McGuire and his colleagues. From the amount of energy being accumulated by subduction, the team of experts estimates undersea thrust earthquakes could occur every 2,000 years. They reported that “unfortunately, high rates of natural erosion in the region have long since wiped away the geological signs of the last earthquake along the submarine fault. We know from historical records that there has not been a quake along the fault in 500 years, but the next one could be within this century or the next millennium,” they said.
McGuire concluded “much larger quakes, of magnitude 8.0 or more, have occurred in this region before and will do so again. In 1843 a magnitude 8.3 earthquake struck the then sparsely populated Leeward Islands killing 5,000 people, according to the USGS. Such an earthquake in today’s densely populated islands will be cataclysmic, to say the least.
“Where these earthquakes are submarine they will present a major tsunami threat, especially as this is such a small area compared with the Indian Ocean,” according to McGuire. Should such a phenomenon occur, most, if not all of the islands in the Caribbean will be devastated. There is a risk too that it could affect us in Guyana where our coast is well below the level of the sea.
Events within recent years have pointed to a resurgence in strong seismic activities and empirical evidence extrapolated from historical records conclude it is no longer a case of “if” but “when” more, and deadly, quakes will strike along the mini-ring of fire in the Caribbean. Geographically, we are not far away from that deadly ring.
Our coastland is becoming more vulnerable by the day as the threat of flooding from rising sea levels caused by global warming becomes more acute and droughts and floods are increasing in frequency and intensity. The need for our country to start peopling and developing the elevated savannah and interior regions must be treated with urgency and proper planning. Unlike the small islands of the Caribbean, we have the geographical alternative of vast tracts of higher ground.
Yours faithfully,
Mahadeo Panchu
