QuakeIndex

Earthquake · reviewed by a seismologist

M 2.6md

Earthquake near Willows, CA

No earthquake was likely felt in Willows in the 24 hours to 6:40 am PST (14:40 UTC). The last one was M 4.0, 65 km (40 mi) W, at 5:01 am PDT on 28 October 2026, estimated intensity II (weak) in town; 14 felt reports to USGS. Every earthquake near Willows

This page: a magnitude 2.6 earthquake was recorded 16 km (10 mi) east of Willows, CA, at 6:02 pm PDT on 2 August 2021 (01:02 UTC), 25 km deep. 1 person has reported feeling it to USGS.

USGS: 16km E of Willows, CA

32 km (20 mi) SSW of Chico, CA · 115 km (71 mi) NNW of Sacramento, CA

6:02 pm PDT, Aug 2, 2021 · · 25 km deep · released about 270 lb of TNT

10 km30 km60 km120 km N Glenn County 35 kmButte County 39 kmColusa County 42 kmSutter County 59 kmYuba County 63 kmTehama County 71 kmLake County 77 kmYolo County 93 kmNevada County 109 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
6:02 pm PDT on 2 August 2021 ()
Where
16 km (10 mi) east of Willows, CA · earthquakes near Willows
Magnitude
M 2.6 (md)
Depth
25 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Glenn County, 35 km WNW
Nearest mapped fault
Great Valley thrust fault system, 24 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 1856 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 Willows, 16 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: Durham, Hamilton City, Biggs, Chico.

How big was it?

This earthquake released about 270 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 57,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 40,000× the energy of this one
  3. Around the size people start to feel M 3.0 3.6× the energy of this one
  4. This earthquake M 2.6 about 270 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:

  1. 5.7 The 1975 Oroville, California Earthquake · 41 km ESE of this epicentre
  2. 5.2 4 km E of Palermo, California · 46 km E of this epicentre
  3. 5.1 5 km ENE of Palermo, California · 46 km E 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 39.5092, -122.0115. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Glenn County, CA 35 km (22 mi) WNW earthquakes near Glenn County
Butte County, CA 39 km (24 mi) ENE earthquakes near Butte County
Colusa County, CA 42 km (26 mi) SSW earthquakes near Colusa County
Sutter County, CA 59 km (37 mi) SSE earthquakes near Sutter County
Yuba County, CA 63 km (39 mi) ESE earthquakes near Yuba County
Tehama County, CA 71 km (44 mi) NNW earthquakes near Tehama 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. 1.8 19 km ESE of Willows, CA
  2. 2.7 14 km E of Willows, CA
  3. 2.1 15 km ESE of Willows, CA
  4. 2.2 5 km ESE of Hamilton City, CA
  5. 2.7 7 km NNE of Hamilton City, CA
  6. 2.4 6 km NNE of Hamilton City, CA
  7. 2.2 6 km NNE of Hamilton City, CA
  8. 3.1 14 km NNE of Maxwell, CA
  9. 2.3 14 km NNE of Maxwell, CA
  10. 2.1 17 km ESE of Willows, CA
  11. 2.1 6 km W of Magalia, CA
  12. 2.3 7 km WNW of Hamilton City, CA
  13. 2.5 8 km E of Orland, CA
  14. 2.7 17 km ESE of Willows, CA
  15. 2.5 17 km ESE of Willows, 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.