Haiti prone to earthquakes, sitting near joint of two solid rocks

The Earth’s crust is made up of tectonic plates that move. And Haiti sits near the intersection of two of them — the North American plate and the Caribbean plate.

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Earthquakes have been wreaking havoc in Haiti since at least the 18th century, when the city of Port-au-Prince was destroyed twice in 19 years. Saturday’s powerful quake killed hundreds and injured thousands more. Eleven years earlier a temblor killed tens of thousands of people, if not hundreds of thousands.

Haiti sits near the intersection of two tectonic plates that make up the Earth’s crust. Earthquakes can occur when those plates move against each other and create friction.

Haiti is also densely populated. Plus, many of its buildings are designed to withstand hurricanes — not earthquakes. Those buildings can survive strong winds but are vulnerable to collapse when the ground shakes.

The Earth’s crust is made up of tectonic plates that move. And Haiti sits near the intersection of two of them — the North American plate and the Caribbean plate.

Multiple fault lines between those plates cut through or near the island of Hispaniola, which Haiti shares with the Dominican Republic. What’s worse, not all of those fault lines behave the same way.

“Hispaniola sits in a place where plates transition from smashing together to sliding past one another,” said Rich Briggs, a research geologist at the U.S. Geological Survey’s Geologic Hazards Science Center.

“It’s like a rock stuck in the track of a sliding glass door,” he said. “It just does not want to move smoothly because it’s got so many different forces on it.”

Saturday’s magnitude 7.2 earthquake likely occurred along the Enriquillo-Plantain Garden fault zone, which cuts across Haiti’s southwestern Tiburon Peninsula, according to the USGS.

It’s the same fault zone along which the devastating 2010 earthquake occurred. And it’s likely the source of three other big earthquakes in Haiti between 1751 and 1860, two of which destroyed Port-au-Prince.

Earthquakes are the result of the tectonic plates slowly moving against each other and creating friction over time, said Gavin Hayes, senior science adviser for earthquake and geologic hazards at USGS.

“That friction builds up and builds up and eventually the strain that’s stored there overcomes the friction,” Hayes said. “And that’s when the fault moves suddenly. That’s what an earthquake is.”

Typical concrete and cinder block buildings can survive strong winds but are vulnerable to damage or collapse when the ground shakes. Poor building practices can also play a role.

The 2010 quake hit closer to densely populated Port-au-Prince and caused widespread destruction. Haiti’s government put the death toll at more than 300,000, while a report commissioned by the U.S. government placed it between 46,000 and 85,000.

“I think it’s important to recognize that there’s no such thing as a natural disaster,” said Wendy Bohon, a geologist with Incorporated Research Institutions for Seismology. “What you have is a natural hazard that overlaps with a vulnerable system.”

Construction of more earthquake-resistant buildings remains a challenge in Haiti, which has remained the poorest nation in the Western Hemisphere.

Before Saturday’s quake, Haiti was still recovering from the 2010 earthquake as well as Hurricane Matthew in 2016. Its president was assassinated last month, sending the country into political chaos.

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