The Red Sismológica Nacional at the Universidad de Costa Rica reported Monday that the country experienced 185 earthquakes in May. That’s an average of six quakes a day.
Most were not felt by humans. The Red said that just 4 percent, some seven quakes, were strong enough to be felt.
Some 70 percent of the quakes were less than 30 kilometers deep. None of the quakes caused significant damage.
The latest felt quake was about 11 kilometers (6 miles) southwest of Liberia in Guanacaste. That had a magnitude of
3.9 and took place at 12:48 p.m. Monday, said the Red.
The Laboratorio de Ingenieria Sismica Instituto de Investigaciones en Ingenieria at the same university estimated the magnitude at 4.0. The epicenter was about eight kilometers inland from the Pacific coast.
All three of Costa Rica’s earthquake monitoring agencies have noted that the area around Quepos is a location of frequent quakes. Some of the quakes reported in a graphic that covers 1973 to 2012 are the result of local faults. But there also is the subduction of the Coco Tectonic Plate under the lighter Caribbean Plate on which most of Costa Rica rides. These are the plates on which continents move above the earth’s molten magma. There also is the Nazca Plate and the Panamá Block to the south that cause quakes. An area of frequent activity is at the Costa Rican border with Panamá.