Haiti and its neighbours must prepare themselves for more massive quakes after the devastating tremors this week increased pressure along a lengthy fault line, scientists have warned.
Paul Mann, a senior research scientist at the Institute for Geophysics at the University of Texas at Austin, warned that just because the rebuilding process had started people shouldn’t assume the risk was over.
“This relief of stress along this area near Port-au-Prince may have actually increased stress in the adjacent segments on the fault,” he told AFP.
Researchers have already begun to work on models to try to predict how the stress changes resulting from the 7.0-magnitude quake which struck Tuesday is affecting the adjacent segments of the fault.
“This fault system is hundreds of kilometers long and the segment that ruptured to form this ear quake is only 80 kilometers long,” Mann said in a telephone interview.
“There are many more segments which are building up strain where there haven’t been earthquakes for hundreds of years.
“Potentially any one of these segments could cause an earthquake similar to that which happened in Haiti.”
There are, thankfully, only two major population centers along the fault: Port-au-Prince and Kingston, Jamaica.
But as demonstrated in the chaos which followed Tuesday’s tremor, the impact of a quake of that magnitude can be “paralyzing,” Mann said.
Adding to the danger is the fact that the segment which broke was not among those closest to Port-au-Prince.
And there is a second fault system in the north of Haiti which extends to the Dominican Republic which has not ruptured in 800 years and has built up sufficient pressure for a 7.5 magnitude quake.
“The question is when are those going to rupture,” Mann said, adding that it is very difficult to predict “whether or not that’s going to happen next week or 100 years.”
Eric Calais, a French geophysicist who works at Purdue University in Indiana, is among those trying to assess the danger.
He had warned Haitian officials years ago of dangerous pressure in the fault which caused this week’s devastating quake, but little could be done to reinforce the desperately poor nation’s weak buildings.
“The Haitian government is not to blame in this,” Calais told AFP.
“They listened to us carefully and they knew what the hazard was. They were very concerned about it and they were taking steps. But it just happened too early.”
Calais began researching the fault line in 2003 and soon took his initial findings to the Haitian government, even meeting with the prime minister.
In March 2008 he and Mann presented a paper showing that the fault had built up sufficient pressure to cause a 7.2 magnitude quake.
But they could not pinpoint when the quake might strike and the government was occupied with recovering from a series of four hurricanes which struck that year.
While the government had begun work on an emergency response plan, little could be done to retrofit and strengthen key buildings such as hospitals, schools and government buildings from which rescue operations could be organized.
“It’s a poor country,” Calais said. “Strengthening a building to resist a large earthquake can be as costly as replacing the building.”
The devastation will allow Haiti to rebuild stronger than before, Calais said, noting that there are relatively cheap engineering solutions that can be applied to ensure that new buildings will not collapse in the next quake.
“It’s very important for Port-au-Prince to rebuild properly,” he added.
“There are other segments of that fault that could rupture in the future.”