Costa Rica suffered remarkably little damage from September 4ths magnitude-7.6 quake — a few blocked highways, some collapsed houses and one death, of a heart attack caused by fright. Officials credited the relatively deep location of the quake and building codes that Costa Rican officials call as strict as those in California and Japan.
The quake was 25 miles (41 kilometers) below the surface. Tremors that occur deep underground tend to be less damaging, but their shaking can be felt over a wider area.
The U.S. Geological Survey said the quake was centered about 38 miles (60 kilometers) from the town of Liberia and 87 miles (140 kilometers) west of the capital, San Jose.
The area is a seismically active zone where the Cocos tectonic plate dives beneath the Caribbean plate. “All along the Pacific coast of Central America, you can expect fairly big earthquakes,” McNamara said.
The quake was followed by roughly 600 aftershocks, including at least three strong ones of magnitudes above 4.
Victor Gonzalez, director of the Volcanic and Seismological Observatory of Costa Rica, told ADN Radio on Thursday that researchers were examining whether the quake had liberated much of the energy built up along the nearby Nicoya Fault, or whether the region was at risk of another large quake. He said there was a possibility of even more aftershocks, including some as powerful as magnitude-6, that could do more damage than the original quake itself.
The relatively little damage from Wednesday’s quake was due in large part to strict building codes in Costa Rica, a country that has long enjoyed more stability, better governance and stronger economic development than many of its Central American neighbors, said Olman Vargas, president of the national College of Architecture and Engineering.
“We have a culture of concrete and steel,” he told The Associated Press. “Years ago we abandoned building in mud and adobe, something that’s caused a lot of problems and that they’re continuing in other countries.”
Costa Rica’s anti-earthquake structural codes have been updated in line with the latest international standards three times since they were enacted in 1974, most recently last year.
Officials said the quake collapsed some houses and at least one bridge and caused landslides that blocked highways. But Costa Rica President Laura Chinchilla said there were no reports of major damage.
About 190 homes were damaged and 203 people are in emergency shelters while officials check if their homes are safe to return to, said David Melendez of National Emergency Commission. Teams with heavy equipment were working to clear the last blocked roads.
Residents described being shocked by the force of the quake, which was felt as far away as Panama and Nicaragua and was the biggest since a 7.6-magnitude quake in 1991 that killed 47 people.