Haitian quake triggered tsunamis
Quake caused a 'slide-generated' tsunami, a dangerous rarity.
Sun, Oct 10, 2010 at 04:31 PM
QUAKES & TSUNAMIS: Homes affected by the 7.0 earthquake in January are seen in Port-au-Prince, Haiti also caused tsunamis. (Photo: Jorge Cruz/AP)
The magnitude 7.0 earthquake that struck Haiti in January, killing a quarter of a million people, also unleashed a string of tsunamis on the country's western coast, scientists reported on Sunday.
Several waves measuring up to 75 centimeters (two and a half feet) were caused by a combination of earth movement and coastal landslides.
They included banks of sediment on the sea bed, accumulated at river deltas, which were displaced by the shock and unleashed the waves as they moved, the study says.
Waves were reported west, north and south of the epicentre, which was within a few kilometers (miles) of the surface on the Enriquillo-Plaintain Garden fault, on the boundaries of two microplates in the Caribbean.
Such "slide-generated" tsunami are rare, but their risk is underestimated, according to the paper, published online in the journal Nature Geoscience.
"Even modest, predominantly strike-slip earthquakes can cause potentially catastrophic slide-generated tsunami," it says.
A strike-slip earthquake occurs when one side of the fault moves along horizontally and in parallel to the other side of the fault, rather than down or up.
Vertical displacement, especially of the seabed, is best known for creating tsunamis.
The study was led by a team led by Matthew Hornbach of the University of Texas at Austin.
The January 12 quake was in tectonic terms a surprisingly complex affair, according to new research. Two-thirds of the movement was strike-slip, and a third was a thrust, or upward, movement.
The quake inflicted huge damage to the capital, Port-au-Prince, injuring 300,000 people and leaving 1.5 million homeless.
Copyright 2010 AFP Global Edition