QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3md

Earthquake near Eureka, CA

No earthquake was likely felt in Eureka in the 24 hours to 2:27 am PST (10:27 UTC). The last one was M 5.0, 128 km (79 mi) WSW, at 8:56 pm PST on 4 November 2026, estimated intensity II (weak) in town; 145 felt reports to USGS. Every earthquake near Eureka

This page: a magnitude 2.3 earthquake was recorded 19 km (12 mi) west of Eureka, CA, at 11:25 am PDT on 26 October 2017 (18:25 UTC), 20 km deep.

USGS: 17 km W of Samoa, California

11:25 am PDT, Oct 26, 2017 · · 20 km deep · released about 85 lb of TNT

Every earthquake near Eureka Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 42 kmDel Norte County 108 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
11:25 am PDT on 26 October 2017 ()
Where
19 km (12 mi) west of Eureka, CA · earthquakes near Eureka
Magnitude
M 2.3 (md)
Depth
20 km below the surface
Felt
no reports yet
Nearest
Humboldt County, 42 km ESE
Nearest mapped fault
Little Salmon fault, 14 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 3303 days ago

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 Eureka, 19 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: Bayview, Humboldt Hill, Cutten, Myrtletown, Pine Hills, Arcata.

How big was it?

This earthquake released about 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 130,000× the energy of this one
  3. Around the size people start to feel M 3.0 11× the energy of this one
  4. This earthquake M 2.3 about 85 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 5,800 times the energy of this one.

Before 2016, the USGS record lists 27 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1980 Eureka, California Earthquake · 34 km NNE of this epicentre
  2. 6.5 The 1932 Eureka, California Earthquake · 14 km SE of this epicentre
  3. 6.5 30 km WSW of Ferndale, California · 47 km SSW of this epicentre
  4. 6.5 The 2010 Eureka, California Earthquake · 32 km SW of this epicentre
  5. 6.4 Northwest of Eureka, California · 21 km NNW 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 40.8303, -124.3920. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 42 km (26 mi) ESE earthquakes near Humboldt County
Del Norte County, CA 108 km (67 mi) NNE earthquakes near Del Norte County
Trinity County, CA 110 km (68 mi) E earthquakes near Trinity County

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

Aftershocks so far

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

  1. 2.3 18km W of Humboldt Hill, CA
  2. 1.6 11km NE of Hydesville, CA
  3. 2.0 10km SSW of Ferndale, CA
  4. 1.7 16km E of Hydesville, CA
  5. 2.2 22km WNW of Petrolia, CA
  6. 2.4 20km WNW of Petrolia, CA
  7. 2.4 11km WSW of Rio Dell, CA
  8. 2.5 20km WNW of Petrolia, CA
  9. 1.7 19km NW of Petrolia, CA
  10. 2.9 18km NW of Petrolia, CA
  11. 2.2 10km S of Ferndale, CA
  12. 2.5 18km WNW of Petrolia, CA
  13. 4.7 22km WNW of Petrolia, CA
  14. 4.4 17km W of Humboldt Hill, CA
  15. 2.5 30km W of Bayview, 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.