Located along what seismologists refer to as “the ring of fire,” a section of earth characterized by volcanic and seismic activity, Costa Rica is certainly not a newcomer to earthquakes. But 2012 marked the final arrival of “The Big One,” an earthquake experts have predicted for decades.
A magnitude-7.6 quake struck five miles off the coast of the Nicoya Peninsula at 8:42 a.m. on Sept. 5, shaking most of the country for 45 long seconds. The natural disaster caused nearly $45 million in damage and minor injuries. A 51-year old woman died of a heart attack following the event, although she was not included in the official quake death toll. It was partly a miracle no one else was killed during the massive temblor. But it also was a testament to Costa Rica’s world-class seismic codes.
The quake made the record books as the country’s second-largest of all time, behind a magnitude-7.7 temblor in 1991, which killed 75 people. Despite its strength, experts and politicians concluded that the anticipated quake could have been much worse.
“Every incident is important,” President Laura Chinchilla told the press the day after the quake, “but this could have been truly catastrophic.”
The last major earthquake to strike the Nicoya Peninsula, in 1950, wreaked havoc on the area, rendering 25 percent of the city of Nicoya’s buildings uninhabitable. Seismologists credit the better outcome both to the depth of the quake and stricter building codes that Costa Rica has been implementing since the mid-1970s.
Damaged buildings included the National Theater in San José and the 400-year-old colonial church in Nicoya. Many homes and other buildings were damaged, and some homeowners criticized the government’s response as too slow or ineffectual.
“I worked eight years and in 10 seconds, wshhhh,” said business owner José Rodolfo Vargas, whose grocery store in Sámara sustained an estimated $12,000 in damage to merchandise.
According to the National Institute for Housing and Urban Development, 140 homes were destroyed in the northwestern province of Guanacaste. An additional 50 homes were deemed unlivable in Alajuela and Puntarenas provinces.
Seismologists registered 530 aftershocks within little more than 24 hours after the temblor. In the next two months, experts estimated more than 4,000 aftershocks had occurred, some reaching magnitudes larger than 6.0. These aftershocks have not been limited to the Guanacaste region, and have been felt primarily in San José and the Central Valley.
According to University of Costa Rica seismologist Wilfredo Rojas, most of the aftershocks were caused by the Cocos and Caribbean plates, the same plates involved in the Sept. 5 earthquake.
While seismologists concluded in September that the quake was indeed the “big one” they had been predicting, it appears the plates still have not released all of their energy. According to the Volcanological and Seismological Observatory of Costa Rica (Ovsicori), research revealed the quake only released 40 percent of built-up energy contained in the plates.
This energy can be released in several different ways, but some seismologists believe that another major earthquake in the Nicoya Peninsula is a realistic possibility.
“Another earthquake of equal or greater magnitude to what occurred on Sept. 5 is a scenario we cannot dismiss,” said Marino Protti, Ovsicori’s lead scientist.