QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near Humboldt Hill, CA

No earthquake was likely felt in Humboldt Hill in the 24 hours to 9:22 pm PST (05:22 UTC). The last one was M 5.0, 123 km (76 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 Humboldt Hill

This page: a magnitude 1.7 earthquake was recorded 2 km (2 mi) southwest of Humboldt Hill, CA, at 10:25 pm PST on 20 November 2020 (06:25 UTC), 9.0 km deep.

USGS: 2km SW of Humboldt Hill, CA

10:25 pm PST, Nov 20, 2020 · · 9.0 km deep · released about 9.3 lb of TNT

Every earthquake near Humboldt Hill Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 24 kmTrinity County 93 kmDel Norte County 117 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
10:25 pm PST on 20 November 2020 ()
Where
2 km (2 mi) southwest of Humboldt Hill, CA · earthquakes near Humboldt Hill
Magnitude
M 1.7 (md)
Depth
9.0 km below the surface
Felt
no reports yet
Nearest
Humboldt County, 24 km E
Nearest mapped fault
Little Salmon fault, 2 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 2180 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 8 km (5 mi) from the epicentre. In Humboldt Hill, 2 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.

Likely felt in: Humboldt Hill 2 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 9.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
  3. Around the size people start to feel M 3.0 100× the energy of this one
  4. This earthquake M 1.7 about 9.3 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 5.6 on 2019-06-23 — about 760,000 times the energy of this one.

Before 2016, the USGS record lists 29 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1980 Eureka, California Earthquake · 45 km N of this epicentre
  2. 7.2 The 1992 Petrolia, California Earthquake · 42 km S of this epicentre
  3. 6.6 32 km SW of Ferndale, California · 47 km SW of this epicentre
  4. 6.5 The 1932 Eureka, California Earthquake · 7 km WNW of this epicentre
  5. 6.5 30 km WSW of Ferndale, California · 43 km SW 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 40.7105, -124.2103. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 24 km (15 mi) E earthquakes near Humboldt County
Trinity County, CA 93 km (58 mi) E earthquakes near Trinity County
Del Norte County, CA 117 km (73 mi) N earthquakes near Del Norte County

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

Aftershocks so far

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

  1. 2.3 1km ENE of Humboldt Hill, CA
  2. 2.5 6km W of Petrolia, CA
  3. 1.8 21km NW of Petrolia, CA
  4. 2.0 14km W of Petrolia, CA
  5. 1.9 8km WSW of Petrolia, CA
  6. 3.0 30km WNW of Ferndale, CA
  7. 1.6 9km WSW of Rio Dell, CA
  8. 1.8 7km N of Petrolia, CA
  9. 2.3 25km WNW of Ferndale, CA
  10. 2.5 14km WNW of Petrolia, CA
  11. 2.5 18km WNW of Petrolia, CA
  12. 2.2 14km S of Rio Dell, CA
  13. 2.2 8km WSW of Petrolia, CA
  14. 2.2 30km E of Rio Dell, CA
  15. 2.2 12km E of Blue Lake, 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.