The quake, which Reuters witnesses said shook buildings in the capital, was centred 35 km west of the coastal city of Valparaiso at a shallow depth of 10 km below the seabed. The USGS initially assessed the temblor as a magnitude 6.7.
Chilean authorities initially ordered a preventative evacuation of the coastal area near Valparaiso, some97 km west of Santiago, in case of a tsunami, but cancelled it shortly afterward.
The Chilean Navy and the Pacific Tsunami Warning Centre said the quake was not expected to cause a tsunami.
The initial assessment by Chile's emergency services was that the quake appeared to have caused no immediate damage.
A magnitude 7.1 quake is considered major and is capable of causing widespread and heavy damage, but the effects of this one would have been tempered because it was offshore.
A Civil Defence spokeswoman said there was no threat of a tsunami reaching New Zealand's coastline and no warnings had been issued.
Photo: US Geological Survey (A strong 7.1-magnitude earthquake struck off the west coast of Chile, near the capital Santiago).