The quake shook an area near Windsor at 7:56 a.m., and had a depth of 2.7 miles, according to the USGS.
Its epicenter was three miles north of Windsor and four miles east-southeast of Healdsburg, according to the USGS.
As of 8:10 a.m., some 18 people in three different ZIP codes in the Santa Rosa area had responded on the USGS website that they felt weak shaking.
