QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Blue Lake, CA

No earthquake was likely felt in Blue Lake in the 24 hours to 2:16 pm PST (22:16 UTC). The last one was M 5.0, 145 km (90 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 Blue Lake

This page: a magnitude 1.8 earthquake was recorded 11 km (7 mi) south-southeast of Blue Lake, CA, at 10:38 pm PST on 8 December 2021 (06:38 UTC), 21 km deep.

USGS: 11km SSE of Blue Lake, CA

10:38 pm PST, Dec 8, 2021 · · 21 km deep · released about 17 lb of TNT

10 km30 km60 km120 km N Humboldt County 10 kmTrinity County 70 kmDel Norte County 106 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
10:38 pm PST on 8 December 2021 ()
Where
11 km (7 mi) south-southeast of Blue Lake, CA · earthquakes near Blue Lake
Magnitude
M 1.8 (md)
Depth
21 km below the surface
Felt
no reports yet
Nearest
Humboldt County, 10 km S
Nearest mapped fault
Mad River fault, under 1 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 1794 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 Blue Lake, 11 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: Bayside, Arcata, Myrtletown, Cutten, Eureka, Pine Hills.

How big was it?

This earthquake released about 17 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 870,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 620,000× the energy of this one
  3. Around the size people start to feel M 3.0 55× the energy of this one
  4. This earthquake M 1.8 about 17 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 29,000 times the energy of this one.

Before 2016, the USGS record lists 17 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1980 Eureka, California Earthquake · 46 km NW of this epicentre
  2. 6.5 The 1932 Eureka, California Earthquake · 32 km WSW of this epicentre
  3. 6.4 The 1954 Eureka-Arcata, California Earthquake · 6 km NNE of this epicentre
  4. 6.0 Near Rio Dell, California · 40 km SW of this epicentre
  5. 5.8 Near Eureka, California · 7 km W 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 40.7950, -123.9185. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 10 km (6 mi) S earthquakes near Humboldt County
Trinity County, CA 70 km (43 mi) ESE earthquakes near Trinity County
Del Norte County, CA 106 km (66 mi) N earthquakes near Del Norte County
Siskiyou County, CA 146 km (90 mi) NE earthquakes near Siskiyou County

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

Aftershocks so far

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

  1. 2.2 12km SSW of Ferndale, CA
  2. 2.3 12km SW of Rio Dell, CA
  3. 2.4 11km SSW of Ferndale, CA
  4. 2.4 11km NNE of Petrolia, CA
  5. 2.6 12km SSW of Ferndale, CA
  6. 3.3 13km SSW of Ferndale, CA
  7. 2.4 12km S of Ferndale, CA
  8. 2.3 8km SSW of Ferndale, CA
  9. 2.5 14km N of Petrolia, CA
  10. 3.1 14km NNE of Petrolia, CA
  11. 3.0 8km SSW of Rio Dell, CA
  12. 2.6 11km WSW of Rio Dell, CA
  13. 2.8 10km SSE of Ferndale, CA
  14. 2.3 12km SW of Rio Dell, CA
  15. 2.6 9km S 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

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