Earthquake · reviewed by a seismologist
M 1.9md
Earthquake near Fort Bragg, CA
No earthquake was likely felt in Fort Bragg in the 24 hours to 4:26 am PST (12:26 UTC). The last one was M 5.0, 186 km (115 mi) NW, at 8:56 pm PST on 4 November 2026, estimated intensity II (weak) in town; 145 felt reports to USGS. Every earthquake near Fort Bragg
This page: a magnitude 1.9 earthquake was recorded 4 km (3 mi) north-northeast of Fort Bragg, CA, at 11:50 am PST on 11 December 2021 (19:50 UTC), 7.6 km deep. 3 people have reported feeling it to USGS.
USGS: 5km NNE of Fort Bragg, CA
- When
- 11:50 am PST on 11 December 2021 ()
- Where
- 4 km (3 mi) north-northeast of Fort Bragg, CA · earthquakes near Fort Bragg
- Magnitude
- M 1.9 (md)
- Depth
- 7.6 km below the surface
- Felt
- 3 reports · strongest reported intensity II
- Nearest
- Mendocino County, 30 km E
- Nearest mapped fault
- Noyo Basin fault, 10 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 1794 days ago
Earthquake alerts for Fort Bragg, CA
Get a notification in this browser when USGS records an earthquake near Fort Bragg, 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 minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth, people at rest would likely notice it out to about 12 km (7 mi) from the epicentre. In Fort Bragg, 4 km away, the estimate is intensity II (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: Fort Bragg 4 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 19 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 810,000× the energy of this one
- Magna, Utah 2020 M 5.7 580,000× the energy of this one
- Around the size people start to feel M 3.0 51× the energy of this one
- This earthquake M 1.9 about 19 lb of TNT
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 4.3 on 2017-12-14 — about 4,000 times the energy of this one.
Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:
- 5.9 9 km S of Leggett, California · 33 km N 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 39.4828, -123.7892. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Mendocino County, CA | 30 km (19 mi) | E | earthquakes near Mendocino County |
| Lake County, CA | 99 km (62 mi) | ESE | earthquakes near Lake County |
| Glenn County, CA | 120 km (74 mi) | E | earthquakes near Glenn County |
| Sonoma County, CA | 130 km (81 mi) | SE | earthquakes near Sonoma County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
55 earthquakes have been recorded within 50 km since this one.
- 2.1 10km SW of Laytonville, CA
- 1.6 12km SSE of Laytonville, CA
- 1.7 4km E of Willits, CA
- 1.6 21km WNW of Ukiah, CA
- 1.9 18km NNW of Laytonville, CA
- 1.8 10km SE of Willits, CA
- 1.6 10km SE of Willits, CA
- 1.8 13km N of Fort Bragg, CA
- 1.7 10km SE of Willits, CA
- 1.5 10km SE of Willits, CA
- 2.0 21km WNW of Ukiah, CA
- 1.7 10km SE of Willits, CA
- 1.8 9km NE of Laytonville, CA
- 1.7 9km SSE of Willits, CA
- 1.5 7km SW of Willits, 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.