The 6.9 magnitude earthquake that shook Costa Rica Sunday night is due to the friction exerted by the seamounts of the Coco plate when it submerges under the Caribbean plate, on which Costa Rica is located.
When sufficient energy is accumulated by the thrust of both plates, one against the other, the energy released translates into termors, explained Ivonne Arroyo, of the Red Sismológica Nacional, of the Universidad de Costa Rica (National Seismological Network of the University of Costa Rica).
From the USGS
The 6.9 quake occurred at 8:28 pm Sunday, southeast of Jaco, (15 km southeast of Esterillos, Lat: 9.4316 Long: -84.5302) in the Central Pacific ocean, at a depth of 19 kms, was felt throughout most of the country.
According to Arroyo, the Central Pacific region is one