Haiti earthquake, deforestation heighten landslide risk
Ker Than National Geographic News
The combination of widespread deforestation and the recent earthquake
in Haiti could lead to more landslides in the already hard-hit country,
scientists say. Many of Haiti’s people, the poorest in the Americas,
routinely cut down trees for fuel, either to burn “raw” or turn into
charcoal.
As a result, the destruction of Haiti’s natural forests is almost
total, making the Caribbean country one of the most deforested in the
world. As Haiti’s trees have disappeared, landslides have become a major
concern, especially during the rainy season, and the destabilizing
effects of an earthquake on soil only worsen the problem.
Natural buffers depleted in Haiti
Forest canopies serve as natural buffers against wind and rain, and
the deep roots of trees help keep the granular soil from shifting.
“If you remove the trees, you have no buffer. So the water”, and
soil, “tends to very quickly move downhill,” said Mark Ashton, a
professor at the Yale School of Forestry and Environmental Studies.
During an earthquake, hillside stability is further threatened as the
ground is shaken.
Earthquake plus rain equals trouble
“Anywhere you have strong motion and steep terrain, you have
extremely high risk of slope failure and landslides, and they can be
extremely large,” said Colin Stark, a geophysicists at the
Lamont-Doherty Earth Observatory in New York. Among the rare bright
spots for Haiti this week are that its capital, Port-au-Prince, is on
relatively flat land, making the landslide threat one less thing to
worry about, and that the earthquake struck during the dry season.
“The worst kinds of landslides would be if you had an earthquake on
rain-soaked soil,” Yale’s Ashton said. The surrounding hilly regions may
not be so lucky, he added. Even without landslides, post-earthquake
pictures show collapsed houses sliding downhill. “It’s where foothills
are that the worst landslides will occur,” he said. “That’s also where
people tend to build their houses.”
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