The earthquake that occurred near Port-Au-Prince, Haiti on January 12, 2010 was one of the worst ever natural disasters. Aid is pouring into the Haitian capital, and aid organizations, and governments from around the world are descending on this Caribbean country. Our hearts go out to the people in Haiti, and we only hope that the aid that is streaming there, and on the ground will reach the people who so desperately need it. For resources, and up-to-the-minute information go the ClintonBushHaiti Fund.
In this post, I am going to talk about the nature of the Haitian earthquake, and what we know about predicting and preparing for earthquakes. We know alot, but we still can not predict earthquakes. Here is some information in light of this tragedy in Haiti.
Enriquillo-Plantain Garden Fault
Roger Musson, a British Geological Survey geologist spoke with Eban Harrell who reported his remarks in a Time online report. According to Musson, the earthquake that happened on Tuesday was what geologists call a strike-slip (or transform) earthquake where one side of fault slides horizontally past the other side.
Diagram of a strike-slip fault, similar to the fault system in Haiti
Musson identified the fault as the Enriquillo-Plantain Garden fault, and it analogous to the San Andreas fault in that this type of fault is the boundary between two crustal plates. As Musson points out, this was the “big one” for this fault in that the previous very large quake here was nearly 200 years ago. In his opinion, the pressure along this fault system has shifted to the West, and he expects another large earthquake in 20 – 40 years in Haiti or Jamaica. He also thinks that the aftershocks will dissipate over the coming days.
Predicting Earthquakes
Can earthquakes be predicted? Could this one in Haiti been predicted. As I said above, the fault system within which the Haitian earthquake happened is analogous to the San Andreas Fault that separates the western edge of the North American Plate from the eastern edge of the Pacific Plate. According to geologists, the Enriquillo-Plantain Garden Fault are studied and monitored to the same degree that geologists have been monitoring and studying the San Andreas Fault in California.
Strike-Slip Arrangement of the San Andreas Fault, an Aerial View
Over long periods of time, 20, 40, 80, 100, 200 years, geologists can say that one could expect an earthquake along a particular fault system. In the case of Haiti, geologists have been predicting that a large earthquake could occur along the boundary between the Caribbean and the North American plate. Earthquakes can not be forecast the way we can forecast a tornado or a thunderstorm, or even a volcanic eruption. Earthquakes go undetected until they happen.
Yet, geologists know a lot about the fault zones here in the Caribbean, and can make general statements about the hazards associated with a fault zone. But still, we are unable to say that an earthquake will happen at a particular time.
Preparing for Earthquakes
The only thing we can do is to prepare for an earthquake. The U.S. Geological Survey has an earthquake hazards program and website that is valuable and would be useful to you in sharing and teaching your students about earthquakes.
The extent of the destruction of the buildings in Port-Au-Prince and the cities and towns near indicate the lack of earthquake-resistant construction. Haiti, which is one of the poorest countries in the Western Hemisphere has not had the financial resources to undertake a comprehensive approach to earthquake-resistant construction. You might recall that the 2008 Sichuan earthquake destroyed thousands of buildings, many of which were schools. Later inspection revealed that most of these schools were built without consideration of earthquakes, and the result was utter disaster, and the death of more than 10,000 school children.
Masonry building destroyed in the Port-Au-Prince
A valuable resource in helping us understand the cause and sources of earthquake damage is National Information Service for Earthquake Engineering. In the case of the earthquake in Haiti, many of the buildings were constructed of unreinforced masonry, which according to engineering geologists is extremely susceptible to damage during an earthquake. The loss of buildings in this city was catastrophic as is evidenced by the pictures we all see on television and on the Internet.
The Destructive Power of Earthquakes
The Haitian earthquake was huge, and because it occurred near a major metropolitan area, several million people have been affected by the quake. Some estimates put the number at 3 million people. In the context of other significant earthquakes, the Haitian earthquake is one of the worst.
Here is a list of the ten most destructive earthquakes compiled by the editors of Time.
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