Earthquake · reviewed by a seismologist
M 4.0mw
Earthquake near Hydesville, CA
No earthquake was likely felt in Hydesville in the 24 hours to 2:39 am PST (10:39 UTC). The last one was M 5.0, 127 km (79 mi) W, at 8:56 pm PST on 4 November 2026, estimated intensity II (weak) in town; 145 felt reports to USGS. Every earthquake near Hydesville
This page: a magnitude 4.0 earthquake was recorded 6 km (4 mi) north-northeast of Hydesville, CA, at 7:09 am PST on 20 December 2022 (15:09 UTC), 23 km deep. 50 people have reported feeling it to USGS.
USGS: 6km NNE of Hydesville, CA
- When
- 7:09 am PST on 20 December 2022 ()
- Where
- 6 km (4 mi) north-northeast of Hydesville, CA · earthquakes near Hydesville
- Magnitude
- M 4.0 (mw)
- Depth
- 23 km below the surface
- Felt
- 50 reports · strongest reported intensity IV
- Measured shaking
- intensity IV (ShakeMap)
- USGS impact alert
- green
- Nearest
- Humboldt County, 17 km NE
- Nearest mapped fault
- Little Salmon fault, 3 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 1353 days ago
Earthquake alerts for Hydesville, 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 small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 93 km (58 mi) from the epicentre. In Hydesville, 6 km away, the estimate is intensity III (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: Fortuna 7 km, intensity III · Rio Dell 12 km, intensity III · Ferndale 17 km, intensity III · Humboldt Hill 17 km, intensity III · Eureka 24 km, intensity III · Bayside 27 km, intensity III · McKinleyville 39 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 12,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 520× the energy of this one
- Magna, Utah 2020 M 5.7 370× the energy of this one
- This earthquake M 4.0 about 15 tons of TNT
- Around the size people start to feel M 3.0 this one released 31× more
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 6.4 on 2022-12-20 — about 4,100 times the energy of this one.
Before 2016, the USGS record lists 33 earthquakes of M5 or more within 50 km; the five largest:
- 7.2 The 1992 Petrolia, California Earthquake · 32 km SSW of this epicentre
- 6.6 32 km SW of Ferndale, California · 48 km WSW of this epicentre
- 6.5 The 1932 Eureka, California Earthquake · 23 km NW of this epicentre
- 6.5 30 km WSW of Ferndale, California · 46 km WSW of this epicentre
- 6.4 The 1954 Eureka-Arcata, California Earthquake · 31 km NNE 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 40.6005, -124.0688. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Humboldt County, CA | 17 km (10 mi) | NE | earthquakes near Humboldt County |
| Trinity County, CA | 81 km (50 mi) | E | earthquakes near Trinity County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 2.3 3km SE of Ferndale, CA
- 2.2 10km NNE of Hydesville, CA
- 2.2 5km SE of Ferndale, CA
- 2.0 16km WSW of Ferndale, CA
- 2.5 14km WSW of Ferndale, CA
- 3.0 19km WSW of Ferndale, CA
- 2.4 7km WSW of Ferndale, CA
- 2.7 3km ENE of Hydesville, CA
- 1.8 9km E of Hydesville, CA
- 2.0 7km SW of Ferndale, CA
- 1.7 14km ENE of Hydesville, CA
- 1.8 2km NW of Hydesville, CA
- 2.6 7km SW of Ferndale, CA
- 1.8 6km SW of Ferndale, CA
- 4.3 6km WSW of Ferndale, 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.