SAN JOSE (Reuters) - A powerful earthquake struck western Costa Rica on Tuesday, shaking buildings in the capital and sending residents running onto the streets, but there were no initial reports of damage or injuries.

Inhabitants of San Jose ran out of buildings after the 6.6 magnitude quake hit, following another big quake last month. Many went back indoors soon afterward, a Reuters witness said.

The quake was centred about 38 miles (61 km) south of Liberia, in Guanacaste province, at a depth of 24.5 miles (39.5 km), the U.S. Geological Survey said. The USGS had initially measured the quake at a significantly shallower depth.

National television station Telenoticias reported that goods fell off shelves in supermarkets in Cabano, a town in Costa Rica's Nicoya peninsula inside Guanacaste.

Both the Red Cross and the National Emergency Commission said no injuries had been registered so far.

The quake struck in a tourist area close to where the Central American nation was rocked by a 7.6 magnitude earthquake on September 5, which damaged buildings but caused no deaths.

Guanacaste's head of police, Rafael Angel Araya, said there had been no reports of damage to buildings or injuries, and that police were heading out to inspect the province.

"They're starting out with any buildings slightly damaged in the previous tremors as a precautionary measure because these are the structures that could potentially fall," he said.

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