Plumas, Sierra and Lassen County residents feel M4.7 earthquake
5:00 p.m. update
The M4.7 earthquake was followed by at least nine small aftershocks throughout Thursday morning, ranging in size from M1.1 to M2.5, with the last one occuring at 8:24 a.m.
The Nevada Seismological Laboratory within the College of Science at the University of Nevada, Reno had this to say about the M4.7 quake on its website, "This right-lateral, strike-slip temblor was sourced at a depth of 12 km. This earthquake is in contrast to the hundreds of smaller quakes that have been recorded beneath Sierraville over the past several months that are noteworthy based on their depth. The Sierraville swarm has seen the majority of small earthquakes at a depth of 29-35 km, and are consistent with magma injection and diking at the crust-mantle boundary."
The M4.7 quake was widely felt across the state, with hundreds of reports each from the Sacramento, Grass Valley, Tahoe, Reno and Chico areas. One response from the south came from San Luis Obispo at a distance of 485 miles and yet another 400 miles to the north in Grants Pass, Oregon. Over 8800 responses have been posted on the "Did You Feel It?" website.
A quick followup call to Sheriff dispatchers in Plumas, Sierra and Lassen counties this morning confirm there are still no reports of damages or injuries.
The quake was in an area known as the Mohawk Valley Fault Zone (MVFZ). Recent research posted on the USGS website about the MVFZ was prepared by the Nevada Bureau of Mines and Geology and gives an extensive history of the seismic activity for the area in a document called Geodetic Constraints on the Slip Rate of the Mohawk Valley Fault Zone, California.
Major news sources including television, radio and newspaper internet websites are incorrectly reporting the epicenter of the quake was in southern Plumas County, when it was really seven miles south of the county line in Sierra County. (See map)
If you'd like to share your "quake" experience, fill out the comment form below or go to our facebook page for plumasnews.com or lassennews.com and hit "comment" under the story.
By 12:30 a.m. over 3900 people in the north state have reported feeling the earthquake at the USGS website. According to both the Sierra County and Plumas County Sheriff dispatchers, there are no reports of damage or injuries at this time.
11:52 p.m. - The earthquake has been downgraded to a 4.7 magnitude.
If you felt it, please comment using the form below and again here at USGS. Northern California residents from Calpine and Chilcoot are reporting this was a moderate quake, and it was felt as far away as Napa and Petaluma at this time.
11:45 p.m. - Residents of Plumas County felt the 5.2 magnitude earthquake centered south of Highway 49, two miles west of Sattley in Sierra County. In Quincy it was a fairly mild shaking about 11:37 p.m. lasting what seemed about 15 seconds, but it was strong enough to get the entire family of this reporter out of bed. Check back here for updates...