QuakeIndex

Earthquake · reviewed by a seismologist

M 2.6ml

56km W of Ferndale, CA

Yes. A magnitude 2.6 earthquake was recorded 56km W of Ferndale, CA, at 12:27 pm PDT on 20 October 2021 (19:27 UTC), 25 km deep.

· 25 km deep · released about 280 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 85 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
Magnitude
M 2.6 (ml)
Depth
25 km below the surface
Felt
no reports yet
Nearest
Humboldt County, 85 km E
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1783 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 1 km (1 mi) from the epicentre. 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 280 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 53,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 38,000× the energy of this one
  3. Around the size people start to feel M 3.0 3.3× the energy of this one
  4. This earthquake M 2.6 about 280 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 5.8 on 2020-03-09 — about 48,000 times the energy of this one.

Before 2016, the USGS record lists 25 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 32 km SW of Ferndale, California · 39 km SE of this epicentre
  2. 6.5 30 km WSW of Ferndale, California · 35 km ESE of this epicentre
  3. 6.5 The 2010 Eureka, California Earthquake · 21 km ENE of this epicentre
  4. 6.3 67 km W of Trinidad, California · 49 km N of this epicentre
  5. 6.0 53 km SW of Ferndale, California · 43 km SSE 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 40.5938, -124.9262. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 85 km (53 mi) E earthquakes near Humboldt County

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

Aftershocks so far

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

  1. 2.6 49km W of Petrolia, CA
  2. 2.9 15km NW of Petrolia, CA
  3. 2.5 40km W of Petrolia, CA
  4. 2.8 25km W of Petrolia, CA
  5. 2.8 38km WNW of Petrolia, CA
  6. 3.2 30km W of Petrolia, CA
  7. 2.7 32km W of Petrolia, CA
  8. 2.6 56km WNW of Ferndale, CA
  9. 2.8 28km W of Petrolia, CA
  10. 2.7 74 km WSW of Ferndale, California
  11. 2.7 30km W of Petrolia, CA
  12. 2.2 25km W of Petrolia, CA
  13. 2.8 18km NW of Petrolia, CA
  14. 2.8 17km NNW of Petrolia, CA
  15. 2.7 44km WNW 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.