A light, 4.7-magnitude earthquake struck in Northern California on Wednesday, according to the United States Geological Survey. The temblor happened at 6:34 p.m. Pacific time about 2 miles northwest of Cobb, Calif., or about 70 miles north of San Francisco, data from the agency shows.

The quake epicenter was 2 miles north-northwest of Cobb, a small community in the hills south of Clear Lake. The epicenter was 70 miles west of Sacramento and 27 miles north of Santa Rosa. A ShakeAlert was issued to cellphone users in portions of Lake, Sonoma, Napa and Mendocino counties, according to the USGS.

A magnitude 4.7 earthquake hit Lake County in Northern California on New Year's Day with no major damage reported.

The U.S. Geological Survey reports a magnitude 4.7 earthquake struck near Cobb in Lake County on Wednesday night.

The tremor struck at 6:34 p.m. and was located 2.3 miles northwest of Cobb, a census designated place 41 miles north of Santa Rosa. Also nearby is the Geysers, an area of frequent seismic activity, which is 4.7 miles north of the quake’s epicenter.

The temblor was initially rated at 4.5 magnitude, then revised to 4.7 roughly a half hour later. Magnitude measures the energy released at the source of the earthquake, the U.S. Geological Survey says.

A magnitude 4.7 earthquake struck in California's Lake County on Wednesday afternoon, the U.S. Geological Survey said. The quake hit at 6:34 p.m. about 2 miles northwest of Cobb at a depth of 0.68 of a mile,