MEXICO CITY -- A strong earthquake struck well off the Pacific coast of western Mexico on Thursday, but authorities said there were no reports of injuries or damage.

The U.S. Geological Survey said the quake had a magnitude of 6.6 and was centred about 134 miles (215 kilometres) southwest of the town of Tomatlan, in Jalisco state. It struck beneath the ocean floor at a depth of 6.2 miles (10 kilometres).

Jalisco's Civil Protection agency said via Twitter that the temblor was felt in several municipalities, but it had no reports of any people being hurt or damaged buildings.

The U.S. National Weather Service's Pacific Tsunami Warning Center said the quake was not forecast to cause a tsunami.