An earthquake that rattled The Geysers area Thursday morning was upgraded to 3.8 magnitude, the U.S. Geological Survey said Friday.
The quake, initially measured at 3.5, struck about 11:30 a.m. and was centered about 14 miles north of Healdsburg in a remote area of Sonoma County. Another 2.4 magnitude quake struck about 10 minutes after.
The USGS said the quake struck 1.6 miles deep.
No injuries were reported.