Oil Drilling Not the Cause of Haiti Earthquake
In the 1920s, geologists in South Texas, an unlikely spot for earthquakes, noted faulting near the Goose Creek oil field. Since then, University of Texas researchers showed that earthquakes in some parts of Texas may be induced by the pumping of fluids at oil and gas fields, or by the injection of fluids to dispose of chemical wastes. For example, the earthquakes in the Fashing-Pleasanton area southeast of San Antonio and in the Texas Panhandle near Snyder, Texas, are almost certainly triggered by pumping.
Like Texas, Haiti infrequently experiences earthquakes. This has prompted numerous stories in the blogosphere "exposing" a link between the devastating 7.0 magnitude earthquake that hit Haiti on January 12th, and oil exploration off its coast. While the devastation caused by the earthquake and its aftershocks is horrifying, as the following analysis shows, the relationship between oil interests and the earthquake is simply a spurious association.
History of Earthquakes in Haiti
Since 1835, Haiti has experienced less than a handful of serious earthquakes. A magnitude 7.7 earthquake in 1842, which destroyed Cap-Haïtien, also ruined the San-Souci Palace (completed in 1813), the so-called Caribbean equivalent of the Palace of Versailles. Earthquakes followed in 1857 and 1870. Also, in 1946, an earthquake off the coast of Haiti reportedly "knocked pedestrians off their feet" and in 2004 a magnitude-4 earthquake struck Haiti following a week of deadly floods.
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Due to the infrequency of earthquakes, Haitians were ill-prepared to respond to to the magnitude-7 shock on January 7th. Instead of running away from their homes and buildings, as would most residents of earthquake-prone areas like San Francisco, Haitians ran for cover during the earthquake as if it were a Hurricane. Since structural weaknesses were reported in the country's schools and buildings as recently as 2008 even in the absence of tremors, over 200,000 Haitians were killed in the destruction that ensued from the 7.0 magnitude earthquake centered just ten miles southwest of the capital of Port-au-Prince, at a shallow depth of 6.2 miles.
Between that initial earthquake on January 12th and the time of writing on February 7th, Haiti has experienced more than 60 additional earthquakes of at least 4.0 magnitude.
How the Quake Unfolded
Earthquakes typically occur near faults or fractures in the Earth's crust where rock formations, driven by the movements of the crustal or tectonic plates that make up the Earth's surface, grind slowly past each other or collide, building up stress. At some point, stress overcomes friction and the rocks slip suddenly, releasing seismic energy in the form of an earthquake, which drops the stress in one area but raises the stress elsewhere along the fault line. Eighty percent of earthquakes on Earth occur on the sea floor and most of them occur along the plate boundaries.
According to the U.S. Geological Survey, the initial earthquake on January 12th occurred in the boundary region separating the Caribbean plate and the North American plate, which slide past each other at a rate of about 0.8 inches (20 mm) per year, with the Caribbean plate moving eastward with respect to the North American plate. The quake stretched between 50 and 60 km (approximately 35 miles) along the Enriquillo-Plaintain Garden fault system, which measures 500 km (310 miles) in length and last produced a major earthquake in 1860. This fault system runs generally east-west through Haiti, to the Dominican Republic to the east and Jamaica to the west.
Although the magnitude of the quake was significant yet smaller than previous earthquakes in Haiti, three factors made it particularly devastating:
(i) it was centered just ten miles southwest of the capital city, Port au Prince;
(ii) the quake was shallow: only about ten to fifteen km (approximately six to nine miles) below the land's surface;
(iii) many homes and buildings in the economically poor country were not built to withstand such a force and collapsed or crumbled.
Alleged Role of Oil Drilling
As the price of oil approached $140 per barrel in the summer of 2008, the prospect of black gold located beneath Haitian territory sparked interest in oil exploration off the country's coast for the first time since 1979.
Four companies participated in the drilling of eleven wells at depths of up to 2,944 meters (nearly 2 miles) located on the mainland of Haiti and Île de la Gonâve, an island off Haiti located to the northwest of Port-au-Prince in the Gulf of Gonâve.
Oil generally is found in permeable sediments that are soft, not in hard rock. When this soft sediment moves, it releases a small amount of energy, which can lead to a "mini-seismic event" that is generally undetected on the Richter scale. Thus, it is highly unlikely that oil drilling would cause a magnitude-7 earthquake, such as the one that occurred on January 12th.
In fact, in 2008, geologists predicted that such a quake would eventually occur. During the 18th Caribbean Geological Conference in March 2008 in Santo Domingo, five scientists presented a paper stating that a fault zone on the south side of Haiti posed "a major seismic hazard." They predicted that a magnitude-7.2 earthquake would result if all of the strain along the fault were "released in a single event today." However, the occurrence of the earthquake was difficult to predict since fault systems like the Enriquillo-Plaintain Garden fault can remain dormant for hundreds of years and the last earthquake in the Port-au-Prince area was in 1770.
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