Earthquake · reviewed by a seismologist
M 2.4md
Earthquake near Hayfork, CA
No earthquake was likely felt in Hayfork in the 24 hours to 3:56 am PST (11:56 UTC). The last one was M 3.7, 42 km (26 mi) W, at 2:44 pm PDT on 7 September 2026, estimated intensity II (weak) in town; 15 felt reports to USGS. Every earthquake near Hayfork
This page: a magnitude 2.4 earthquake was recorded 32 km (20 mi) west of Hayfork, CA, at 8:17 pm PDT on 28 August 2021 (03:17 UTC), 24 km deep.
USGS: 32km W of Hayfork, CA
- When
- 8:17 pm PDT on 28 August 2021 ()
- Where
- 32 km (20 mi) west of Hayfork, CA · earthquakes near Hayfork
- Magnitude
- M 2.4 (md)
- Depth
- 24 km below the surface
- Felt
- no reports yet
- Nearest
- Humboldt County, 33 km WNW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1896 days ago
Earthquake alerts for Hayfork, CA
Get a notification in this browser when USGS records an earthquake near Hayfork, 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 it was probably too small to be felt, even directly above it. In Hayfork, 32 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.
How big was it?
This earthquake released about 100 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 140,000× the energy of this one
- Magna, Utah 2020 M 5.7 100,000× the energy of this one
- Around the size people start to feel M 3.0 9.1× the energy of this one
- This earthquake M 2.4 about 100 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 4.8 on 2016-07-21 — about 4,700 times the energy of this one.
Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:
- 6.4 The 1954 Eureka-Arcata, California Earthquake · 39 km NW of this epicentre
- 5.8 Near Eureka, California · 43 km WNW of this epicentre
- 5.6 15 km SW of Burnt Ranch, California · 13 km NNW of this epicentre
- 5.4 3 km NNW of Burnt Ranch, California · 26 km N of this epicentre
- 5.0 2 km E of Rio Dell, California · 46 km WSW 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 40.6060, -123.5563. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Humboldt County, CA | 33 km (21 mi) | WNW | earthquakes near Humboldt County |
| Trinity County, CA | 38 km (23 mi) | E | earthquakes near Trinity County |
| Tehama County, CA | 124 km (77 mi) | ESE | earthquakes near Tehama County |
| Siskiyou County, CA | 139 km (86 mi) | NE | earthquakes near Siskiyou County |
| Glenn County, CA | 149 km (92 mi) | SE | earthquakes near Glenn 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.
- 3.6 14km SE of Bayside, CA
- 1.6 29km W of Hayfork, CA
- 1.8 22km E of Hydesville, CA
- 2.4 17km N of Redway, CA
- 2.0 15km NNE of Redway, CA
- 2.1 17km ESE of Pine Hills, CA
- 2.2 2km ESE of Hydesville, CA
- 2.1 22km E of Willow Creek, CA
- 2.6 6km NNW of Hayfork, CA
- 2.4 22km SE of Blue Lake, CA
- 1.7 24km N of Redway, CA
- 2.0 10km NNW of Willow Creek, CA
- 2.1 30km WNW of Weaverville, CA
- 2.9 30km WNW of Weaverville, CA
- 2.1 29km E of Hydesville, 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.