Haiti Earthquake: Fault Visible from Space

Jan. 20, 2010 — -- It is not as if the earthquake in Haiti was a surprise to the world's seismologists.

They had known for decades about the fault line that caused it, and some geologists, including Eric Calais of Purdue University and Paul Mann of the University of Texas, had warned as recently as 2008 that when the fault gave way, the result could be a quake of up to 7.2 magnitude.

"Such studies should be considered high priority in Jamaica, Haiti and the Dominican Republic, given the seismic hazards posed by the fault," they wrote at the time.

The Enriquillo-Plantain Garden fault, as it is known to geologists, appears as an almost straight cut in the earth in radar images from the space shuttle Endeavour, recorded 10 years ago on the STS-99 mission in February 2000.

See the arrows in the false-color image of Haiti above (NASA's Jet Propulsion Laboratory, which ran the mission, has a large version posted HERE).

You are looking eastward in this picture. The Plantain Garden fault shows as a straight, sharp cut in the mountains. Elevations in this computer-generated image are exaggerated by a factor of two.

The U.S. Geological Survey says the fault probably caused a major earthquake in Jamaica in 1907, and written descriptions suggest it caused powerful quakes in 1860, 1770, 1761, 1751, 1684, 1673, and 1618.

But in recent decades the two sides of the fault line had been locked in place as they ground against each other and stresses built up in the ground.

"This fault was locked in a way that it didn't produce a lot of small quakes," said Art Lerner-Lam of the Lamont-Doherty Earth Observatory of Columbia University in Palisades, N.Y.

Without those small quakes as a reminder of the greater threat, people in the area put up cheap buildings, made from cinderblock and tin.

U.S. scientists say they understand: Haiti was so poor it could barely deal with day-to-day concerns, much less the long-term threat of an earthquake.

Seismologists emphasize that they are still very far from predicting earthquakes, since the ground beneath our feet is by nature chaotic. But last week's earthquake in Haiti had a reported magnitude of 7.0, so the warning by Mann, Calais and their colleagues of a 7.2 quake was not far off.