QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9md

Earthquake near Ukiah, CA

Yes: an earthquake was likely felt in Ukiah in the last 24 hours. M 1.5, 10 km (6 mi) NE of Ukiah, at 12:31 pm PST on 11 November 2026 (20:31 UTC); the estimated shaking in Ukiah was intensity II (weak). Every earthquake near Ukiah

This page: a magnitude 2.9 earthquake was recorded 48 km (30 mi) north-northeast of Ukiah, CA, at 11:03 am PST on 8 December 2019 (19:03 UTC), 11 km deep. 3 people have reported feeling it to USGS.

USGS: 15km N of Lake Pillsbury, CA

11:03 am PST, Dec 8, 2019 · · 11 km deep · released about 720 lb of TNT

10 km30 km60 km120 km N Mendocino County 42 kmGlenn County 49 kmLake County 52 kmColusa County 75 kmTehama County 90 kmSonoma County 113 kmButte County 118 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
11:03 am PST on 8 December 2019 ()
Where
48 km (30 mi) north-northeast of Ukiah, CA · earthquakes near Ukiah
Magnitude
M 2.9 (md)
Depth
11 km below the surface
Felt
3 reports · strongest reported intensity III
Nearest
Mendocino County, 42 km WSW
Nearest mapped fault
Bartlett Springs fault system, 3 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 2447 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 31 km (19 mi) from the epicentre. In Ukiah, 48 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.

How big was it?

This earthquake released about 720 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 21,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 15,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.3× the energy of this one
  4. This earthquake M 2.9 about 720 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 1,800 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 · 49 km SSW 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 39.5450, -122.9708. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mendocino County, CA 42 km (26 mi) WSW earthquakes near Mendocino County
Glenn County, CA 49 km (31 mi) E earthquakes near Glenn County
Lake County, CA 52 km (33 mi) SSE earthquakes near Lake County
Colusa County, CA 75 km (47 mi) ESE earthquakes near Colusa County
Tehama County, CA 90 km (56 mi) NE earthquakes near Tehama County
Sonoma County, CA 113 km (71 mi) S earthquakes near Sonoma County

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

Aftershocks so far

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

  1. 2.0 12km WNW of Redwood Valley, CA
  2. 1.5 13km SE of Covelo, CA
  3. 2.6 5km SW of Redwood Valley, CA
  4. 1.7 4km N of Redwood Valley, CA
  5. 1.8 3km NW of Redwood Valley, CA
  6. 1.5 9km E of Willits, CA
  7. 1.6 10km ESE of Willits, CA
  8. 1.9 12km NNW of Covelo, CA
  9. 1.6 11km NNW of Covelo, CA
  10. 1.6 11km NNW of Covelo, CA
  11. 1.6 13km WNW of Alder Springs, CA
  12. 1.6 16km N of Lake Pillsbury, CA
  13. 1.9 5km NNE of Alder Springs, CA
  14. 3.1 6km SE of Laytonville, CA
  15. 2.0 1km WSW of Redwood Valley, 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.