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A preliminary magnitude-6.9 earthquake struck off the Mexican coast, 165 miles west southwest of Cihuatlan, Jalisco at 10:07 a.m. PT on Thursday, Jan. 21, 2016.
A magnitude-6.6 earthquake struck well off the Pacific coast of Jalisco, Mexico on Thursday morning.

The quake initially registered at 6.9 in magnitude but was later downgraded to 6.6, according to the U.S. Geological Survey.

The quake struck at 10:07 a.m. PT and was centered 134 miles southwest of Tomatlan and 158 miles west of Cihuatlan, USGS said.

Jalisco's Civil Protection agency said via Twitter that it was monitoring the state's 125 municipalities to rule out any damage.

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

The Associated Press contributed to this report.