Haiti earthquake: Why the Caribbean is a mini ring of fire
The forces that led to the Haiti earthquake are a reminder that the idyllic Caribbean is one of the more geologically active spots on earth, and that a powerful earthquake could strike the region again.
What once was a river bed seen along the streets of Port-au-Prince, Haiti, is now a massive garbage dump, Monday.
Mary Knox Merrill/Staff
Boston
Last week's devastating earthquake in Haiti and yesterday's magnitude 5.9 aftershock (downgraded by the US Geological Survey after an initial report estimated it at 6.1) serve as tragic reminders that as idyllic as many spots in the Caribbean Sea may seem, they can periodically be dangerous too.
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The region is no stranger to volcanoes and earthquakes, thanks to the interaction of one of the smallest – yet one of the most complex – crustal plates on the planet.
Known as the Caribbean Plate, this slowly migrating, slowly morphing patch of Earth's crust exhibits virtually every feature found on the world's largest plates.
It's home to a spreading center – one of the deepest on Earth – where new material emerges from deep beneath the crust to replenish the sea floor. Portions of it are bounded by subduction zones, where one crustal plate plunges beneath another. Some of these trigger the formation of volcanoes. It has a platelet, a kind of smaller plate within a plate, on which the island of Hispaniola – home to Haiti and the Dominican Republic – rides. And it exhibits the kind of long, side-slipping faults similar to California's San Andreas Fault.
"The Caribbean is very complicated," says Jian Lin, a geophysicist at the Woods Hole Oceanographic Institution in Woods Hole, Mass. "It's small to start with, but you have everything in plate tectonics in this very small region."
Those processes have helped raise and sculpt a set of islands – from the Caymans to the Antilles – that are picturesque, geologically active, and occasionally dangerous as populations have grown.
The Jan. 12 temblor centered near the Haitian capital of Port-au-Prince has vaulted it to the top of the list of most devastating quakes to hit the Caribbean. UN and other officials estimate that the death toll will reach well into the tens of thousands of people.
That eclipses the previous record-holder – a quake that hit the Leeward Islands in 1843. That struck as a magnitude 8.3 quake, killing 5,000 people, according to US Geological Survey data.
It took a volcanic eruption on Martinique in 1902 to approximate the devastation last week's quake inflicted on Haiti. That year Mt. Pelee erupted, hurling ash and superheated gas toward the town of St. Pierre. The eruption destroyed the town and killed some 30,000 people.
The Caribbean Plate was born deep beneath the ocean some 90 million to 100 million years ago, Dr. Lin explains, during a virtual tectonic tour of the Caribbean. It likely emerged via a "hot spot" in the Pacific at a time when the world's land masses were configured in a dramatically different way. Instead of leading to towering volcanic islands, the way a hot spot has formed the Hawaiian chain, the hot spot spawning the Caribbean Plate extended over a wide region, with magma oozing through fissures and vents and spreading horizontally to form a vast undersea plateau.
