Damage to roads, houses and hotels. Insured losses expected to be minimal.

A strong earthquake struck Costa Rica on Thursday, 8 January at 19:21 UTC. The U.S. Geological Survey (USGS) initially estimated the moment magnitude to be 6.2, but later revised the magnitude downward to 6.1. The epicenter was located about 35 km (22 miles) northwest of the capital city, San Jose, at an estimated depth of 4.5 km (2.8 miles). The quake was felt throughout the country, and as far away as parts of neighboring Nicaragua. Since Thursday, the main event has been followed by over 1,200 minor aftershocks.

"The tectonic framework of Costa Rica is complex as a result of four plates and microplates interacting: the Cocos, Caribbean, Nazca and the Panama block," explained Dr. Guillermo Franco, senior research engineer at AIR Worldwide. "The subduction of the Cocos plate creates a continuous range of volcanoes as well as crustal faults running from the northwest to southeast through Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica. The historical seismicity indicates that those active crustal faults can generate large earthquakes, which characterise a significant hazard to the cities located on this zone. Costa Rica is located on the Pacific Ring of Fire, which forms a belt of seismic activity along the edge of the Pacific Ocean."

Extensive road damage has destroyed bridges and cut off main highway access to Poas Volcano, one of Costa Rica's main tourist attractions. The areas around Sarapiqui, Santa Barbara and Poas were the hardest hit with damage reported to some houses and hotels. Power and communications were temporarily interrupted.

"Most of the insured building stock in Costa Rica consists of confined masonry construction, followed by reinforced concrete of varying seismic performance," continued Dr. Franco. "There are also some unreinforced masonry buildings throughout the country, which are often uninsured, as well as small quantities of wood and steel construction."

Costa Rica has one of the strictest building codes in Central America. Its first version was developed in 1974 and later modified in the 1980s. Its latest building code version dates from 2002.

Because take-up rates in the affected region are low, insured losses resulting from this event are expected to be minimal, according to AIR.