By Mica Rosenberg:
PORT-AU-PRINCE, Haiti (Reuters) -- Haiti should be preparing for another major earthquake that could be triggered by the catastrophic one last month which killed up to 200,000 people and left the capital Port-au-Prince in ruins, experts say.
Teams of geophysicists, who have been tracking movements in the fault line that slashes across Haiti and into the Dominican Republic, came to the nation last week to measure changes in the Earth's crust after the 7.0-magnitude quake on January 12.
Increased pressure on the fault after the quake could unleash another of the same size or bigger, although scientists acknowledge they have no way of knowing exactly when or where it will hit.
"Faults are always waiting for the right moment but if another earthquake gives them a little kick they go before their time," said Eric Calais, a professor of geophysics from Purdue University in Indiana, who is leading the seismology project in Haiti.
Preliminary calculations by his group show the January 12 quake could be the "little kick" that sets off another temblor along the 186 mile fault where two regional tectonic plates have been scraping together for millions of years.
More than 50 aftershocks, including one measuring 5.9 magnitude, have shaken Port-au-Prince after last month's quake. The US Geological Survey says the aftershock sequence will continue for months, "if not years", and "damaging earthquakes will remain possible in the coming months".
Calais was due to take his findings to a meeting on Monday with President Rene Preval and the head of the United Nations mission in Haiti, in which he would stress the urgent need to rebuild the city's critical infrastructure safely and quickly.
Haiti's government has announced plans to relocate up to half a million homeless quake victims -- many now camped out in rubble-strewn streets -- in temporary villages outside of Port-au-Prince. But some experts suggest the whole capital should be rebuilt away from the dangerous fault line.
Calais was part of a group of experts who warned Haitian officials in 2008 that there could be a 7.2 magnitude quake on the horizon.
But Haitian officials said there was not enough time or funds to shore up the impoverished Caribbean's country's shoddy construction or take precautions, and in last month's quake, many buildings pancaked, their bricks crumbling to dust.
"It's not too late. Now is the time to really get serious about this," Calais said.
Over 200 years ago, when Haiti saw its last major earthquake, there were actually several temblors in a row, two in 1751 and another in 1770, Calais said.
In one destroyed neighborhood in the Haitian capital, where people now live in tents made of bed sheets and sticks, curious children watched the scientists set up specialized global positioning systems. The devices, placed at different points along the fault, will gather data over three days and compare it to information gathered over the past five years.
But for all the precise measurements, there is no such thing as an exact science of earthquake prediction.
Haiti's national geological survey offices collapsed in the quake, killing some 30 people inside, including the institute's director. This complicates future research in a country that has no seismic network, except for Calais' GPS monitors.
"Scientists are blind when it comes to this earthquake ... We rely on data that is coming from stations that are far away," he said.
"It's like if you go to your doctor and the only thing we can do is look at you with binoculars -- so the diagnostic would be pretty poor."
February 2, 2010
caribbeannetnews
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Showing posts with label Haiti fault line. Show all posts
Showing posts with label Haiti fault line. Show all posts
Tuesday, February 2, 2010
Sunday, January 31, 2010
Haiti must learn to live with earthquakes, experts say
By Jordi Zamora:
PORT-AU-PRINCE, Haiti (AFP) -- It will be difficult to convince Haitians to spend extra money and rebuild their quake-ravaged country with structures able to withstand another powerful earthquake, experts said Friday.
Some 170,000 people were killed in the devastating January 12 quake that toppled weak buildings across the Haitian capital.
Two fault lines run under the island of Hispaniola, which Haiti shares with the Dominican Republic, but Haitians have long forgotten about the danger of earthquakes.
"Between six and eight generations of people have gone by who lived with no awareness of earthquakes," Haitian engineer Hans Zennid told AFP.
The previous earthquakes known to have struck the island nation took place in 1742, 1772 and 1842, said Zennid. The 1842 quake was so devastating it forced the government to move the capital from Cap Haitien to its current location.
Despite the devastation, President Rene Preval has said that Port-au-Prince will continue being Haiti's capital.
The presidential palace, built in the 1920s, the Congress building, and virtually every ministry building collapsed when the magnitude 7.0 earthquake struck.
However an 11-floor building belonging to the telephone company towers over the rubble, largely intact.
Zennid was the engineer responsible for making sure that building was earthquake-ready.
"From the start I planned to make the building strong enough to resist a magnitude 6.0 earthquake, because the possibilities of a 7 (magnitude) like the one that just happened is something that happens every 150 years," said Zennid, as he surveyed the building.
A report by US structural engineers giving people the green light to use the building is posted at the entrance, perhaps to ease the fears of workers desperately seeking a semblance of normality. The report said that only one of the pillars suffered minimum damage.
Zennid said he increased the building's strength after a soil analysis.
"When we began to lay the building foundation and I analyzed the soil quality, I added 20 percent to the security level, which allowed it to resist a 7.3," he said.
That meant adding 15 percent more reinforced concrete and steel to the foundation, which meant increasing the cost by some 150,000 dollars.
At first his employers "were upset, but in the end they accepted the price increase," he said.
Haiti's elegant presidential palace can be rebuilt on the same site, even keeping the same style, Zennid said, but engineers will have to completely re-work the building's foundation.
That also applies to the vast majority of homes in Port-au-Prince, including the most luxurious mansions and hotels, many of which collapsed when the quake struck, he said.
As in most underdeveloped countries, even rich Haitians tend to expand their homes in stages instead of building them according to a single, structurally sound blueprint.
In order to do that builders need a large pot of money, and "there is no tradition of home loans here," said French architect Christian Dutour, who has carried out several projects in Haiti.
It will be difficult to explain the importance of proper building codes to a population that overwhelmingly lives below the poverty line.
In the noisy, chaotic streets of Port-au-Prince, street vendors are already selling metal rods salvaged from the earthquake rubble.
According to the US Geological Survey (USGS), which tracks earthquakes around the world, Haiti's quake could represent the beginning of a new cycle of earthquakes after nearly 170 years of geological peace.
The quake's epicenter was just 25 kilometers (15 miles) from Haiti and struck at a very shallow depth of 13 kilometers (eight miles).
The USGS estimated recently that there was a 25 percent probability that one or several magnitude 6 aftershocks could strike in the coming weeks, although they will space out more and more over time.
The January 12 quake freed much of the tension accumulated on one portion of the Enriquillo-Plantain Garden fault, which runs along the southern portion of Hispaniola -- but another segment east of the epicenter and adjacent to Haiti's capital Port-au-Prince has barely moved, according to the USGS.
"We are sitting on a powder keg," geologist Claude Prepetit, an engineer from the Haitian Mines and Energy bureau, told AFP.
"We are faced with the threat of future earthquakes and have to decentralize, and depopulate Port-au-Prince," he said.
January 30, 2010
caribbeannetnews
PORT-AU-PRINCE, Haiti (AFP) -- It will be difficult to convince Haitians to spend extra money and rebuild their quake-ravaged country with structures able to withstand another powerful earthquake, experts said Friday.
Some 170,000 people were killed in the devastating January 12 quake that toppled weak buildings across the Haitian capital.
Two fault lines run under the island of Hispaniola, which Haiti shares with the Dominican Republic, but Haitians have long forgotten about the danger of earthquakes.
"Between six and eight generations of people have gone by who lived with no awareness of earthquakes," Haitian engineer Hans Zennid told AFP.
The previous earthquakes known to have struck the island nation took place in 1742, 1772 and 1842, said Zennid. The 1842 quake was so devastating it forced the government to move the capital from Cap Haitien to its current location.
Despite the devastation, President Rene Preval has said that Port-au-Prince will continue being Haiti's capital.
The presidential palace, built in the 1920s, the Congress building, and virtually every ministry building collapsed when the magnitude 7.0 earthquake struck.
However an 11-floor building belonging to the telephone company towers over the rubble, largely intact.
Zennid was the engineer responsible for making sure that building was earthquake-ready.
"From the start I planned to make the building strong enough to resist a magnitude 6.0 earthquake, because the possibilities of a 7 (magnitude) like the one that just happened is something that happens every 150 years," said Zennid, as he surveyed the building.
A report by US structural engineers giving people the green light to use the building is posted at the entrance, perhaps to ease the fears of workers desperately seeking a semblance of normality. The report said that only one of the pillars suffered minimum damage.
Zennid said he increased the building's strength after a soil analysis.
"When we began to lay the building foundation and I analyzed the soil quality, I added 20 percent to the security level, which allowed it to resist a 7.3," he said.
That meant adding 15 percent more reinforced concrete and steel to the foundation, which meant increasing the cost by some 150,000 dollars.
At first his employers "were upset, but in the end they accepted the price increase," he said.
Haiti's elegant presidential palace can be rebuilt on the same site, even keeping the same style, Zennid said, but engineers will have to completely re-work the building's foundation.
That also applies to the vast majority of homes in Port-au-Prince, including the most luxurious mansions and hotels, many of which collapsed when the quake struck, he said.
As in most underdeveloped countries, even rich Haitians tend to expand their homes in stages instead of building them according to a single, structurally sound blueprint.
In order to do that builders need a large pot of money, and "there is no tradition of home loans here," said French architect Christian Dutour, who has carried out several projects in Haiti.
It will be difficult to explain the importance of proper building codes to a population that overwhelmingly lives below the poverty line.
In the noisy, chaotic streets of Port-au-Prince, street vendors are already selling metal rods salvaged from the earthquake rubble.
According to the US Geological Survey (USGS), which tracks earthquakes around the world, Haiti's quake could represent the beginning of a new cycle of earthquakes after nearly 170 years of geological peace.
The quake's epicenter was just 25 kilometers (15 miles) from Haiti and struck at a very shallow depth of 13 kilometers (eight miles).
The USGS estimated recently that there was a 25 percent probability that one or several magnitude 6 aftershocks could strike in the coming weeks, although they will space out more and more over time.
The January 12 quake freed much of the tension accumulated on one portion of the Enriquillo-Plantain Garden fault, which runs along the southern portion of Hispaniola -- but another segment east of the epicenter and adjacent to Haiti's capital Port-au-Prince has barely moved, according to the USGS.
"We are sitting on a powder keg," geologist Claude Prepetit, an engineer from the Haitian Mines and Energy bureau, told AFP.
"We are faced with the threat of future earthquakes and have to decentralize, and depopulate Port-au-Prince," he said.
January 30, 2010
caribbeannetnews
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