Earthquake · reviewed by a seismologist
M 1.7md
Earthquake near Fort Bragg, CA
No earthquake was likely felt in Fort Bragg in the 24 hours to 5:52 am PST (13:52 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 1.7 earthquake was recorded 26 km (16 mi) north-northeast of Fort Bragg, CA, at 7:50 am PDT on 4 September 2022 (14:50 UTC), 4.8 km deep.
USGS: 16km SE of Rockport, CA
- When
- 7:50 am PDT on 4 September 2022 ()
- Where
- 26 km (16 mi) north-northeast of Fort Bragg, CA · earthquakes near Fort Bragg
- Magnitude
- M 1.7 (md)
- Depth
- 4.8 km below the surface
- Felt
- no reports yet
- Nearest
- Mendocino County, 31 km SE
- Nearest mapped fault
- Maacama fault, 12 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 1530 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 12 km (7 mi) from the epicentre. In Fort Bragg, 26 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 12 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,300,000× the energy of this one
- Magna, Utah 2020 M 5.7 900,000× the energy of this one
- Around the size people start to feel M 3.0 80× the energy of this one
- This earthquake M 1.7 about 12 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 6,200 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 · 15 km NNW of this epicentre
- 5.5 7 km ESE of Shelter Cove, California · 48 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 39.6537, -123.6697. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Mendocino County, CA | 31 km (19 mi) | SE | earthquakes near Mendocino County |
| Lake County, CA | 100 km (62 mi) | SE | earthquakes near Lake County |
| Glenn County, CA | 109 km (68 mi) | E | earthquakes near Glenn County |
| Humboldt County, CA | 119 km (74 mi) | N | earthquakes near Humboldt County |
| Trinity County, CA | 120 km (75 mi) | NNE | earthquakes near Trinity 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.
- 1.9 8km SE of Willits, CA
- 2.8 9km SSW of Cape Vizcaino, CA
- 1.9 9km SSW of Cape Vizcaino, CA
- 2.2 16km NNE of Brooktrails, CA
- 1.7 16km NNE of Brooktrails, CA
- 2.2 13km WSW of Laytonville, CA
- 2.5 6km ENE of Covelo, CA
- 2.3 6km ENE of Covelo, CA
- 1.6 16km ENE of Brooktrails, CA
- 1.5 11km NNE of Brooktrails, CA
- 1.7 20km NNE of Rockport, CA
- 1.7 18km NW of Lake Pillsbury, CA
- 1.9 11km W of Laytonville, CA
- 2.5 5km E of Covelo, CA
- 1.7 19km NNW of Laytonville, 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.