San José, Costa Rica, since 1956

Could a tsunami happen in Costa Rica?

Residents along the Pacific coast last Friday braced for trouble after the U.S. government’s Pacific Tsunami Warning Center (PTWC) issued a warning for Costa Rica in the wake of a massive earthquake and deadly tsunamis that devastated Japan. Although waves caused only minor damage here, videos of the devastation in Japan prompted an uneasy question: Is Costa Rica at risk for a tsunami?

A tsunami occurs when an earthquake, volcanic eruption or movement beneath an ocean or lake results in massive waves. Massive earthquakes with epicenters located just offshore caused the tsunami that struck Japan last week and a deadly 2004 tsunami in Indonesia.

According to the Volcanological and Seismological Observatory of Costa Rica (Ovsicori), in January and February 484 tremors or earthquakes registered above 1.0 on the Richter scale. Last Friday, a small quake shook the Nicoya Peninsula, where most seismic activity occurs in Costa Rica.

“Many quakes happen on the Nicoya Peninsula when the Coco and Caribbean plates shift beneath the peninsula,” said Evelin Núñez, seismologist at Ovsicori. “There is also a subduction zone beneath the peninsula where the two plates meet. This causes many tremors and small earthquakes, though Nicoya is not the only region of the country in seismic risk.”

Other seismic areas include the Southern Zone, where the Coco, Nazca and Panama plates are joined, and the central Pacific region near Quepos.

In 2009, when a 6.1-magnitude earthquake struck Cinchona in Alajuela, killing dozens, Ovsicori recorded 6,000 earthquakes in the country. In the past four years, the number of quakes has averaged 4,793.

Yet despite abundant seismic activity, the likelihood of a massive earthquake and tsunami happening here is low.

“Due to the geomorphologic structure of our country, in Costa Rica there is a very small chance that an earthquake could produce a tsunami of a very large intensity,” Núñez told The Tico Times. “It is worthy of mention that, should a large earthquake occur in the Caribbean, the eastern part of the country could be at risk of a tsunami.”

A 1991 earthquake in Limón produced only small waves on the Caribbean coast. In the aftermath of large earthquakes in South America, small tsunami waves did manage to hit Costa Rican shores. But to date, no large-scale tsunami has been recorded in Costa Rica. 

Preventive Measures

Japanese seismology expert Chuske Irabu has lived in Costa Rica for two years and has spent most of his time on the Nicoya Peninsula. Irabu, who is part of a worldwide seismologist exchange program, spends his time in Nicoya educating families on what they should do in case of a large earthquake or tsunami.

“We go door-to-door to inform people of Nicoya what to do in case of an earthquake and how to prepare for one prior to it occurring,” he told The Tico Times this week. “We have also given several presentations to the area police, firefighters and schools on how to prepare and react to earthquakes. We are trying to provide them with as much information as we can.”

Irabu, who is from the Okinaba Island in Japan, says there is an education system in place in Japan that prepares citizens for earthquakes. He says the system begins in the schools, where children are educated how to respond to an earthquake, and continues in the communities, where police and firemen give presentations in highly seismic regions.

As for Costa Rica, Irabu says he has seen a lack of preparation and overall lack of concern at the possibility of an earthquake in Nicoya.

“Some people respond very well, but many people don’t believe an earthquake is going to happen. They think all the talk of an earthquake is sort of a lie,” he said. “There hasn’t been a major earthquake in 60 years and they aren’t concerned about one happening. It can be a little frustrating. Just because an earthquake hasn’t happened in 20, 30 or 60 years doesn’t mean one won’t happen any time soon. It actually makes the probability higher.”

In his two years in Nicoya, Irabu says he has only felt one small earthquake, though continues to go door-to-door instructing people how to prepare for the possibility of something bigger.

As for his thoughts on Japan, Irabu said that he thinks the Japanese government needs to learn from the experience to prepare for the very worst scenarios.

“The area has had many earthquakes, but no one ever imagined that one of this magnitude could occur,” he said. “All over the world, nations need to rethink their plans and prepare for the very worst. I think Japan has showed us that things we can’t even imagine can happen.” 

Irabu said for Costa Rica, the first step in preparation is new home and building construction. The innumerable small, wood-framed homes of Nicoya would be in danger of collapse if a large earthquake or tsunami hit the peninsula.

“The rumor of a large earthquake hitting this region has been repeated for years,” he said. “Will one happen? No one really knows. But, with all the seismic activity in the area, preparing for one would be a very intelligent decision.” 

Comments are closed.