Tuesday aftershock near Santa Rosa upgraded to 4.3 magnitude

The U.S. Geological Survey has upgraded the magnitude of the aftershock that rattled the North Bay seconds after an initial earthquake Tuesday evening.

The aftershock was a 4.3 magnitude shaker, according to the USGS, which initially reported the magnitude at 3.9.

The aftershock struck at 6:40 p.m., 42 seconds after the initial 4.4 magnitude quake began, according to the USGS.

The initial temblor was centered within Santa Rosa city limits, about 2 miles northeast of the city’s center. A USGS map shows the epicenter just west of Parker Hill Road, north of Chanate Road.

The aftershock was centered roughly a mile away. Its epicenter was on the east side of Parker Hill, also slightly north of Chanate.

There were no reports of major damage or injuries.

Authorities in Santa Rosa responded to several reports of gas leaks, but many were unfounded, according to police Sgt. Chris Mahurin.

The quakes were on the Rodgers Creek fault, which is part of the San Andreas system, according to seismologist Lucy Jones.

(From 2016: New maps detail wider Rodgers Creek fault through Santa Rosa)

The Rodgers Creek fault, known as a strike-slip fault, runs from San Pablo Bay at the southern tip of Sonoma County north through Santa Rosa to Healdsburg. It is also part of the Hayward fault system.

It runs along Santa Rosa's east side — from Taylor Mountain, through Doyle Park, near Providence Santa Rosa Memorial Hospital and past the Santa Rosa Rural Cemetery.

The last big earthquake along the Rodgers Creek fault occurred 53 years ago, on Oct. 1, 1969, when a 5.6 magnitude quake hit just before 10 p.m. and was followed 90 minutes later by a 5.7 magnitude quake. A third temblor, 3.8 magnitude, occurred about six hours after the second, according to Press Democrat reports at the time

More than 100 buildings were damaged or destroyed in those 1969 quakes, including 13 hotels, and the total loss exceeded $7 million, according to the USGS. Nobody was killed but there were several minor injuries reported.

You can reach Staff Writer Matt Pera at matthew.pera@pressdemocrat.com. On Twitter @Matt__Pera.