Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near Brooktrails, CA
No earthquake was likely felt in Brooktrails in the 24 hours to 6:16 am PST (14:16 UTC). The last one was M 4.0, 38 km (23 mi) E, at 5:01 am PDT on 28 October 2026, estimated intensity III (weak) in town; 14 felt reports to USGS. Every earthquake near Brooktrails
This page: a magnitude 1.6 earthquake was recorded 14 km (9 mi) north-northeast of Brooktrails, CA, at 9:51 am PDT on 17 September 2021 (16:51 UTC), 8.3 km deep.
USGS: 14km NNE of Brooktrails, CA
- When
- 9:51 am PDT on 17 September 2021 ()
- Where
- 14 km (9 mi) north-northeast of Brooktrails, CA · earthquakes near Brooktrails
- Magnitude
- M 1.6 (md)
- Depth
- 8.3 km below the surface
- Felt
- no reports yet
- Nearest
- Mendocino County, 17 km SSW
- Nearest mapped fault
- Maacama fault, 8 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 1878 days ago
Earthquake alerts for Brooktrails, CA
Get a notification in this browser when USGS records an earthquake near Brooktrails, 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 8 km (5 mi) from the epicentre. In Brooktrails, 14 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: Willits, Laytonville, Covelo.
How big was it?
This earthquake released about 7.8 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,900,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
- Around the size people start to feel M 3.0 120× the energy of this one
- This earthquake M 1.6 about 7.8 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 2019-04-29 — about 12,000 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 · 41 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 39.5660, -123.3457. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Mendocino County, CA | 17 km (11 mi) | SSW | earthquakes near Mendocino County |
| Lake County, CA | 73 km (45 mi) | SE | earthquakes near Lake County |
| Glenn County, CA | 81 km (50 mi) | E | earthquakes near Glenn County |
| Colusa County, CA | 105 km (65 mi) | ESE | earthquakes near Colusa County |
| Tehama County, CA | 114 km (71 mi) | ENE | earthquakes near Tehama County |
| Sonoma County, CA | 121 km (75 mi) | SSE | earthquakes near Sonoma County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
54 earthquakes have been recorded within 50 km since this one.
- 1.8 6km SE of Lake Pillsbury, CA
- 1.7 13km SE of Laytonville, CA
- 2.1 9km NNW of Lake Pillsbury, CA
- 1.6 7km NE of Willits, CA
- 2.0 10km NNW of Redwood Valley, CA
- 1.8 9km NNW of Redwood Valley, CA
- 1.7 4km E of Redwood Valley, CA
- 2.1 4km E of Redwood Valley, CA
- 3.1 3km E of Covelo, CA
- 2.2 10km ESE of Willits, CA
- 1.6 6km ESE of Redwood Valley, CA
- 1.5 16km E of Mendocino, CA
- 1.9 5km NNE of Fort Bragg, CA
- 2.2 12km N of Brooktrails, CA
- 1.7 12km N of Brooktrails, 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.