The U.S. Geological Survey is reporting an earthquake with a preliminary magnitude of 3.1 struck this morning in Santa Clara County.

The quake shook an area near Alum Rock at 4:51 a.m. and had a depth of 5.5 miles, according to the USGS.

Its epicenter was about 5 miles east of Alum Rock and 9 miles northeast of San Jose City Hall.