Earthquake · reviewed by a seismologist
M 3.1ml
Earthquake near Cobb, CA
Yes: an earthquake was likely felt in Cobb in the last 24 hours. M 1.6, 4 km (2 mi) W of Cobb, at 1:30 pm PST on 11 November 2026 (21:30 UTC); the estimated shaking in Cobb was intensity II (weak). Every earthquake near Cobb
This page: a magnitude 3.1 earthquake was recorded 4 km (2 mi) northwest of Cobb, CA, at 7:05 am PST on 11 November 2021 (15:05 UTC), 1.7 km deep. 25 people have reported feeling it to USGS.
USGS: 4km NW of Cobb, CA
45 km (28 mi) N of Santa Rosa, CA · 122 km (76 mi) NNW of San Francisco, CA
- When
- 7:05 am PST on 11 November 2021 ()
- Where
- 4 km (2 mi) northwest of Cobb, CA · earthquakes near Cobb
- Magnitude
- M 3.1 (ml)
- Depth
- 1.7 km below the surface
- Felt
- 25 reports · strongest reported intensity IV
- Nearest
- Lake County, 29 km N
- Nearest mapped fault
- Konocti Bay fault, 5 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1762 days ago
Earthquake alerts for Cobb, CA
Get a notification in this browser when USGS records an earthquake near Cobb, CA. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 43 km (27 mi) from the epicentre. In Cobb, 4 km away, the estimate is intensity III (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.
Likely felt in: Cobb 4 km, intensity III · Clearlake 16 km, intensity III · Cloverdale 24 km, intensity II · Lakeport 26 km, intensity II · Healdsburg 28 km, intensity II · Calistoga 33 km, intensity II · Windsor 34 km, intensity II · Upper Lake 38 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 1,500 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 230,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 10,000× the energy of this one
- Magna, Utah 2020 M 5.7 7,200× the energy of this one
- This earthquake M 3.1 about 1,500 lb of TNT
- Around the size people start to feel M 3.0 this one released 1.6× more
Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.
For this area
The largest earthquake within 50 km since 2016 was M 5.0 on 2016-12-14 — about 660 times the energy of this one.
Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:
- 5.2 6 km ESE of Talmage, California · 42 km NW of this epicentre
Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.
Where
Epicentre 38.8478, -122.7472. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lake County, CA | 29 km (18 mi) | N | earthquakes near Lake County |
| Sonoma County, CA | 39 km (24 mi) | SSW | earthquakes near Sonoma County |
| Napa County, CA | 53 km (33 mi) | SE | earthquakes near Napa County |
| Colusa County, CA | 57 km (36 mi) | NE | earthquakes near Colusa County |
| Yolo County, CA | 76 km (47 mi) | ESE | earthquakes near Yolo County |
| Mendocino County, CA | 88 km (55 mi) | NW | earthquakes near Mendocino County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
57 earthquakes have been recorded within 50 km since this one.
- 1.9 7km WSW of The Geysers, CA
- 1.5 10km NW of The Geysers, CA
- 1.7 4km W of Cobb, CA
- 1.6 3km NW of The Geysers, CA
- 1.6 7km W of Cobb, CA
- 1.9 7km W of Cobb, CA
- 1.7 4km NNW of Larkfield-Wikiup, CA
- 1.6 2km NW of The Geysers, CA
- 2.1 8km SW of Calistoga, CA
- 2.5 7km SW of Calistoga, CA
- 1.5 9km WNW of Cobb, CA
- 1.7 2km W of Anderson Springs, CA
- 2.0 4km WNW of The Geysers, CA
- 1.5 14km E of Boonville, CA
- 1.8 1km NE of The Geysers, CA
Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.
On USGS
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.