QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8md

Earthquake near Willits, CA

No earthquake was likely felt in Willits in the 24 hours to 3:55 am PST (11:55 UTC). The last one was M 1.5, 9 km (5 mi) ESE, at 10:30 pm PST on 2 November 2026, estimated intensity II (weak) in town. Every earthquake near Willits

This page: a magnitude 2.8 earthquake was recorded 9 km (6 mi) east-southeast of Willits, CA, at 6:06 am PDT on 5 May 2021 (13:06 UTC), 4.3 km deep. 42 people have reported feeling it to USGS.

USGS: 9km ESE of Willits, CA

6:06 am PDT, May 5, 2021 · · 4.3 km deep · released about 510 lb of TNT

10 km30 km60 km120 km N Mendocino County 17 kmLake County 54 kmGlenn County 78 kmColusa County 91 kmSonoma County 99 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
6:06 am PDT on 5 May 2021 ()
Where
9 km (6 mi) east-southeast of Willits, CA · earthquakes near Willits
Magnitude
M 2.8 (md)
Depth
4.3 km below the surface
Felt
42 reports · strongest reported intensity III
Nearest
Mendocino County, 17 km WNW
Nearest mapped fault
Maacama fault, 4 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 1951 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, people at rest would likely notice it out to about 28 km (17 mi) from the epicentre. In Willits, 9 km away, the estimate is intensity III (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: Willits 9 km, intensity III · Brooktrails 13 km, intensity III · Ukiah 26 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 510 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 30,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 21,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.9× the energy of this one
  4. This earthquake M 2.8 about 510 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 5.1 on 2016-08-10 — about 2,500 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.2 6 km ESE of Talmage, California · 32 km SSE 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 39.3763, -123.2617. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mendocino County, CA 17 km (10 mi) WNW earthquakes near Mendocino County
Lake County, CA 54 km (33 mi) ESE earthquakes near Lake County
Glenn County, CA 78 km (48 mi) ENE earthquakes near Glenn County
Colusa County, CA 91 km (56 mi) ESE earthquakes near Colusa County
Sonoma County, CA 99 km (62 mi) SSE earthquakes near Sonoma County
Tehama County, CA 121 km (75 mi) NE earthquakes near Tehama County

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

Aftershocks so far

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

  1. 1.6 11km SE of Laytonville, CA
  2. 1.9 2km N of Lake Pillsbury, CA
  3. 1.8 2km NNW of Lake Pillsbury, CA
  4. 2.0 1km NNE of Lake Pillsbury, CA
  5. 1.6 9km NW of Redwood Valley, CA
  6. 1.7 11km ESE of Redwood Valley, CA
  7. 1.6 7km ESE of Willits, CA
  8. 2.8 7km ESE of Willits, CA
  9. 2.5 7km ESE of Willits, CA
  10. 1.8 4km NNE of Lake Pillsbury, CA
  11. 2.7 15km ESE of Lake Pillsbury, CA
  12. 1.9 4km NNW of Laytonville, CA
  13. 2.2 12km E of Navarro Head, CA
  14. 1.8 10km SE of Willits, CA
  15. 1.6 8km ENE of Willits, 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.