SANTIAGO (Reuters) - A magnitude 6.7 earthquake hit the coast of north-central Chile, the US Geological Survey said. The quake struck about 15.6 km (9.7 miles) south-southwest of Coquimbo, the USGS said. The relatively shallow quake, just 53 km (33 miles) below the surface, rattled buildings in the capital city of Santiago. The Pacific Tsunami Warning Center discarded a tsunami threat shortly after the tremor. No initial damage or injuries have been reported, though there were sporadic reports of power outages near the epicenter of the quake. Chilean miner Antofagasta Plc said operations were normal at its Los Pelambres copper mine following the nearby earthquake.