QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8mw

Earthquake near Ferndale, CA

No earthquake was likely felt in Ferndale in the 24 hours to 2:43 am PST (10:43 UTC). The last one was M 5.0, 113 km (70 mi) W, at 8:56 pm PST on 4 November 2026, estimated intensity III (weak) in town; 145 felt reports to USGS. Every earthquake near Ferndale

This page: a magnitude 3.8 earthquake was recorded 12 km (8 mi) south-southwest of Ferndale, CA, at 12:57 pm PST on 31 December 2021 (20:57 UTC), 19 km deep. 161 people have reported feeling it to USGS.

USGS: 12km SSW of Ferndale, CA

12:57 pm PST, Dec 31, 2021 · · 19 km deep · released about 7.8 tons of TNT

Every earthquake near Ferndale Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 42 kmTrinity County 104 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
12:57 pm PST on 31 December 2021 ()
Where
12 km (8 mi) south-southwest of Ferndale, CA · earthquakes near Ferndale
Magnitude
M 3.8 (mw)
Depth
19 km below the surface
Felt
161 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
Nearest
Humboldt County, 42 km NE
Nearest mapped fault
Little Salmon fault, 22 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 1713 days ago

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 81 km (50 mi) from the epicentre. In Ferndale, 12 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: Ferndale 12 km, intensity III · Rio Dell 19 km, intensity III · Fortuna 20 km, intensity III · Humboldt Hill 30 km, intensity III · Eureka 39 km, intensity II · Bayside 46 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 7.8 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 22,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 970× the energy of this one
  3. Magna, Utah 2020 M 5.7 680× the energy of this one
  4. This earthquake M 3.8 about 7.8 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 16× 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 6.2 on 2021-12-20 — about 3,800 times the energy of this one.

Before 2016, the USGS record lists 43 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1992 Petrolia, California Earthquake · 18 km SSE of this epicentre
  2. 6.6 32 km SW of Ferndale, California · 22 km WSW of this epicentre
  3. 6.5 The 1932 Eureka, California Earthquake · 28 km N of this epicentre
  4. 6.5 30 km WSW of Ferndale, California · 21 km WSW of this epicentre
  5. 6.5 The 2010 Eureka, California Earthquake · 36 km WNW 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 40.4778, -124.3288. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 42 km (26 mi) NE earthquakes near Humboldt County
Trinity County, CA 104 km (65 mi) E earthquakes near Trinity County
Mendocino County, CA 139 km (86 mi) SSE earthquakes near Mendocino County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

58 earthquakes have been recorded within 50 km since this one.

  1. 2.6 22km E of Hydesville, CA
  2. 2.8 6km SW of Petrolia, CA
  3. 2.7 31km W of Petrolia, CA
  4. 2.2 12km SSW of Ferndale, CA
  5. 1.6 12km SSW of Ferndale, CA
  6. 1.9 12km SSW of Ferndale, CA
  7. 2.2 12km SSW of Ferndale, CA
  8. 2.7 12km SSW of Ferndale, CA
  9. 2.0 12km SSW of Ferndale, CA
  10. 1.8 12km SSW of Ferndale, CA
  11. 1.8 12km SSW of Ferndale, CA
  12. 1.7 12km SSW of Ferndale, CA
  13. 1.8 10km WSW of Petrolia, CA
  14. 2.6 41km W of Petrolia, CA
  15. 2.7 31km W of Petrolia, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.