QuakeIndex

Earthquake · reviewed by a seismologist

M 2.6md

Earthquake near Ferndale, CA

No earthquake was likely felt in Ferndale in the 24 hours to 3:18 am PST (11:18 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 2.6 earthquake was recorded 20 km (13 mi) south-southwest of Ferndale, CA, at 5:11 pm PDT on 31 July 2017 (00:11 UTC), 29 km deep.

USGS: 20 km SSW of Ferndale, California

5:11 pm PDT, Jul 31, 2017 · · 29 km deep · released about 210 lb of TNT

Every earthquake near Ferndale Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 50 kmTrinity County 110 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
5:11 pm PDT on 31 July 2017 ()
Where
20 km (13 mi) south-southwest of Ferndale, CA · earthquakes near Ferndale
Magnitude
M 2.6 (md)
Depth
29 km below the surface
Felt
no reports yet
Nearest
Humboldt County, 50 km NE
Nearest mapped fault
Mattole Canyon fault, 18 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 3381 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 it was probably too small to be felt, even directly above it. In Ferndale, 20 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: Rio Dell, Fortuna, Hydesville.

How big was it?

This earthquake released about 210 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 72,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 51,000× the energy of this one
  3. Around the size people start to feel M 3.0 4.6× the energy of this one
  4. This earthquake M 2.6 about 210 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 4.4 on 2016-01-02 — about 660 times the energy of this one.

Before 2016, the USGS record lists 44 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1992 Petrolia, California Earthquake · 16 km SE of this epicentre
  2. 6.6 32 km SW of Ferndale, California · 15 km WSW of this epicentre
  3. 6.5 The 1932 Eureka, California Earthquake · 36 km NNE of this epicentre
  4. 6.5 30 km WSW of Ferndale, California · 16 km W of this epicentre
  5. 6.5 The 2010 Eureka, California Earthquake · 37 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 40.4162, -124.3803. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 50 km (31 mi) NE earthquakes near Humboldt County
Trinity County, CA 110 km (68 mi) ENE earthquakes near Trinity County
Mendocino County, CA 135 km (84 mi) SE 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. 3.0 12km WSW of Petrolia, CA
  2. 3.8 20km WSW of Petrolia, CA
  3. 2.3 9km WSW of Petrolia, CA
  4. 2.7 20km N of Redway, CA
  5. 3.9 28km WNW of Petrolia, CA
  6. 2.8 5km NE of Hydesville, CA
  7. 2.8 4km SSW of Humboldt Hill, CA
  8. 2.3 19km W of Petrolia, CA
  9. 2.1 5km SW of Humboldt Hill, CA
  10. 2.5 5km WSW of Humboldt Hill, CA
  11. 1.8 15km ESE of Hydesville, CA
  12. 2.6 34km WNW of Petrolia, CA
  13. 2.6 48km W of Ferndale, CA
  14. 2.4 10 km SSW of Ferndale, California
  15. 3.0 38 km SW of Ferndale, California

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.