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| #1 - Posted 20 November 2010, 8:09 AM | |
Location: United States, NYC Join date: October 2009 Member #: 3761 Posts: 12112  | New Study Points to More Earthquakes for Hispaniola If you think things are rather difficult these days, just imagine-if you can-how much worse the issues that have us glued to the news about the island will be WHEN not IF another, perhaps far greater in intensity earthquake hits the island of Hispaniola. According to new data a team of 10 expert geologists have unearthed a previously unknown fault line, The Léogâne fault, that accounted for the vast portion of the energy released last January 12, 2010. Thus, the assumed role of the long known fault, the Enriquillo, was minimal at best in the outcome of that tragic event in January. More importantly, this means that Enriquillo is still due to unleash its huge store of energy and potentially cause an even greater deadly aftermath than the January 12 disaster. For the DR, the study is important for various reasons, but the single most important one was that the portion of energy release in Jan 12th by the Enriquillo fault was in its western portion. Thus the likelihood that the next time out, the Eastern portion's energy build-up will be in play. DR will be in greater danger, as of course will be Haiti. For Haiti there are potentially more fault lines still to be uncovered in the north; thus making the mapping of the nation an important consideration before any substantial investment is made in re-locating and building new structures. As with Haiti, the DR must guard against being too complaisant in building code violations and insist on solid compliance across the nation. The question of the next Big One is not "IF" but "When."  A woman and child attend Mass next to the rubble of the Notre-Dame cathedral in Port-au-Prince, Haiti, on Nov. 14, 2010 Emilio Morenatti / AP Underneath Haiti, Another Big Quake Waiting to Occur By Tim Padgett / Port-au-Prince Friday, Nov. 19, 2010 Last week, on the morning of Nov. 11, a tremor shook the Port-au-Prince suburb of Carrefour. It was a minor geological event, but given the still fresh and haunting memories of the 7.0-magnitude earthquake that hammered Haiti on Jan. 12 and killed some 230,000 people — many of them in Carrefour — even that mild shudder caused public panic. The only reported injuries, in fact, were due to people scrambling to take cover. To geologists, it's good to see Haitians on such heightened alert. Most scientists believe the western hemisphere's poorest country is hardly out of the seismic woods — and after studying the Haiti quake data for the past 10 months, they're more convinced than ever that Haitians can expect another major quake sooner rather than later. That's largely because they've found, according to a new study by 10 prominent geologists, that the lion's share of the January temblor occurred not along the fault line they originally suspected, known as the Enriquillo–Plantain Garden fault zone, but on a previously unknown fault. (Faults separate plates in the earth's crust, which cause quakes when stress makes them collide.) As a result, says Falk Amelung, a University of Miami geologist and one of the report's authors, "the prospects of another serious event may be rather worse than we first thought." When Amelung and other geologists started poring over information from the earthquake's satellite-radar images last January, they were flummoxed by a variety of features. One was the vertical motion the quake exhibited — unusual because the Enriquillo, which runs across Haiti's southern peninsula just below Port-au-Prince, is a strike-slip fault, the kind that almost exclusively displays horizontal motion when it ruptures. At the same time, the quake's horizontal movement was partly north-south, another anomaly for a strike-slip fault. "Those were the two important smoking guns" that made scientists question their early assumptions about the quake, says Eric Calais, a Purdue University geologist who is in Haiti as a science adviser to the U.N. Development Program and is a lead author of the study, which was published last month in Nature Geoscience.(See more about the January earthquake that devastated Haiti.) There were others. Why, for example, did the earthquake's rupture not reach the surface, despite its strength? And, perhaps most important, why did so little of the Enriquillo fault itself seem to rupture? The answer, say the geologists, is that another, unmapped fault line parallel to the Enriquillo was also involved, one they've now identified and named the Léogâne, for the city west of Port-au-Prince where the quake had its epicenter. The Léogâne fault, they add, seems to be a combination of a strike-slip and a thrust fault (which helps explain the vertical motion and other unexpected behavior) and was responsible for about 85% or more of the quake's energy. But even with the important discovery of the Léogâne fault, geologists say Haiti is still left with an ominous reality: the larger Enriquillo has yet to fire much if not most of its volatile seismic ammunition. Before January, the fault hadn't had a major rupture since 1751. Scientists have observed that only the western half of the segment that broke in 1751 came apart this time, meaning the eastern portion — closest to Port-au-Prince — is now likely a geological hair trigger. In fact, the discovery of the Léogâne fault, as geologists like Amelung suggest, may mean things are more dangerous than previously imagined, since it indicates the Enriquillo spent even less of its own energy in the January earthquake than they had assumed.(Comment on this story.) Calais, however, thinks the Léogâne's appearance "is no reason to be alarmist." In the study, Calais agrees that on Hispaniola, the Caribbean island Haiti shares with the Dominican Republic, "vulnerability to earthquake shaking will probably remain high in the near future." But finding the new fault, he tells TIME, "doesn't mean Port-au-Prince is more or less exposed than it was before. It's still sitting on a [seismic] time bomb that Haiti had unfortunately ignored before Jan. 12, and which we and the Haitians now have to focus on more closely." Geologists like Amelung's Miami colleague, Tim Dixon, began to identify the Enriquillo fault as a major Caribbean quake hazard in the 1980s. New leaps in satellite imagery and GPS technology, spearheaded by organizations like the Japanese space agency JAXA and the international Group on Earth Observations, helped make the new fault discovery possible. It's sure to renew discussion about whether Haiti should rebuild away from its overpopulated southern capital, although scientists now fear there may be hidden faults to the north as well. More important, it's another reminder that Haiti has to rebuild smarter — the quake's death toll could have been slashed if the country hadn't allowed so much shoddy concrete construction and poor urban planning — so that when the next big quake does hit places like Carrefour, Haitians can escape horrors like those of January 2010. Read more: http://www.time.com/time/world/article/0,8599,2031863,00.html#ixzz15p2bS0JE Edited on 11/21/2010 10:29 PM by Atabey. "If you want to sleep well at night, it's best to avoid watching the making of sausages or politics." Otto Von Bismarck |
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| #2 - Posted 20 November 2010, 11:53 AM | |
 Location: Dominican Republic, La Romana Join date: January 2009 Member #: 2040 Posts: 14 | RE: New Study Points to More Earthquakes for Hispaniola Earthquake forecasting and predictions carry still much uncertainty, speculation and guessing. The next earthquake could happen in Hispaniola tomorrow, in another 250 years or maybe never. Construction cost of earthquake proof vertical structures can increase costs about 20% or more, depending on the desire magnitude prevention. In a poor country like Haiti it is doubtful that new buildings for the masses that are living in tents now, will take the message on this article as serious and something to consider, due to the obvious budget limitations. But the Dominican Republic should pay close attention to the perils ahead and plan and build smaller buildings, per square feet, but more resistant to tremors, and at the same time with better energy efficiency. Edited on 11/20/2010 11:57 AM by travelwriter. |
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| #3 - Posted 20 November 2010, 12:51 PM | |
Location: United States, NYC Join date: October 2009 Member #: 3761 Posts: 12112 | RE: New Study Points to More Earthquakes for Hispaniola Quote: travelwriter previously said: Earthquake forecasting and predictions carry still much uncertainty, speculation and guessing. The next earthquake could happen in Hispaniola tomorrow, in another 250 years or maybe never. Construction cost of earthquake proof vertical structures can increase costs about 20% or more, depending on the desire magnitude prevention. In a poor country like Haiti it is doubtful that new buildings for the masses that are living in tents now, will take the message on this article as serious and something to consider, due to the obvious budget limitations. But the Dominican Republic should pay close attention to the perils ahead and plan and build smaller buildings, per square feet, but more resistant to tremors, and at the same time with better energy efficiency. What you say about earthquake prediction is very true. However, given that the expectation were for the Enriquillo fault to trigger the last major earthquake, it's understandable for these scientist and others to try and influence Haiti along a better or less unfavorable pathway in reconstructing its housing stock. Certainly, I would hope that better and safer construction take place, and given Haiti's low wage structure, low cost, quality housing, may yet come about. As for the DR. You are on point. More needs to be done to secure that the building codes are sound, and in those situation where things need to be secured or corrected that the follow-up be professionally addressed. DR can build high and sound. Other nations have and DR need not allow itself to follow the dreaded urban sprawl that one sees in Mexico and across too many landscapes. In fact, I would go further and outlaw the building of single family unit housing if the financing is public. And those who insist on building single family homes should pay taxes and the like as if they owned a two family house. Encourage better land use and control urban sprawl. "If you want to sleep well at night, it's best to avoid watching the making of sausages or politics." Otto Von Bismarck |
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