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 4:56 pm PST (00:56 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 36 km (22 mi) north-northeast of Fort Bragg, CA, at 8:21 am PST on 11 December 2017 (16:21 UTC), less than 1 km deep.
USGS: 11km E of Rockport, CA
- When
- 8:21 am PST on 11 December 2017 ()
- Where
- 36 km (22 mi) north-northeast of Fort Bragg, CA · earthquakes near Fort Bragg
- Magnitude
- M 1.9 (md)
- Depth
- 0.9 km below the surface
- Felt
- no reports yet
- Nearest
- Mendocino County, 42 km SSE
- Nearest mapped fault
- Maacama fault, 11 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 3257 days ago
Earthquake alerts for Fort Bragg, CA
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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 15 km (9 mi) from the epicentre. In Fort Bragg, 36 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.
Earthquakes near other towns within 30 km: Laytonville.
How big was it?
This earthquake released about 25 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 600,000× the energy of this one
- Magna, Utah 2020 M 5.7 420,000× the energy of this one
- Around the size people start to feel M 3.0 38× the energy of this one
- This earthquake M 1.9 about 25 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 4.1 on 2016-11-06 — about 1,500 times the energy of this one.
Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:
- 5.9 9 km S of Leggett, California · 5 km NW of this epicentre
- 5.5 7 km ESE of Shelter Cove, California · 38 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 39.7548, -123.6902. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Mendocino County, CA | 42 km (26 mi) | SSE | earthquakes near Mendocino County |
| Humboldt County, CA | 108 km (67 mi) | N | earthquakes near Humboldt County |
| Lake County, CA | 108 km (67 mi) | SE | earthquakes near Lake County |
| Trinity County, CA | 111 km (69 mi) | NNE | earthquakes near Trinity County |
| Glenn County, CA | 112 km (69 mi) | E | earthquakes near Glenn County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
53 earthquakes have been recorded within 50 km since this one.
- 2.2 5km N of Fort Bragg, CA
- 1.6 7km SSW of Laytonville, CA
- 1.5 1km ENE of Redway, CA
- 2.1 13km NNE of Rockport, CA
- 1.6 5km NW of Laytonville, CA
- 1.9 13km N of Brooktrails, CA
- 1.8 7km ENE of Covelo, CA
- 1.8 28km SE of Redway, CA
- 1.6 20km N of Covelo, CA
- 2.4 4km NNW of Laytonville, CA
- 1.6 7km SW of Laytonville, CA
- 2.2 4km NNW of Laytonville, CA
- 2.1 4km NNW of Laytonville, CA
- 1.7 17km NE of Fort Bragg, CA
- 2.0 8km NE of Covelo, 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.