QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

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 1.6 earthquake was recorded 42 km (26 mi) east-northeast of Ukiah, CA, at 2:15 pm PST on 22 February 2018 (22:15 UTC), 12 km deep.

USGS: 19km ESE of Lake Pillsbury, CA

2:15 pm PST, Feb 22, 2018 · · 12 km deep · released about 7.3 lb of TNT

10 km30 km60 km120 km N Lake County 23 kmGlenn County 45 kmColusa County 48 kmMendocino County 59 kmSonoma County 89 kmSutter County 97 kmNapa County 98 kmTehama County 101 kmYolo County 103 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
2:15 pm PST on 22 February 2018 ()
Where
42 km (26 mi) east-northeast of Ukiah, CA · earthquakes near Ukiah
Magnitude
M 1.6 (md)
Depth
12 km below the surface
Felt
no reports yet
Nearest
Lake County, 23 km S
Nearest mapped fault
Bartlett Springs fault system, 5 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 3184 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 Ukiah, 42 km away, the estimate is intensity I (not felt). 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: Upper Lake, Nice, North Lakeport.

How big was it?

This earthquake released about 7.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,500,000× the energy of this one
  3. Around the size people start to feel M 3.0 130× the energy of this one
  4. This earthquake M 1.6 about 7.3 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 5.1 on 2016-08-10 — about 180,000 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 · 36 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 39.3135, -122.7687. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, CA 23 km (14 mi) S earthquakes near Lake County
Glenn County, CA 45 km (28 mi) NE earthquakes near Glenn County
Colusa County, CA 48 km (30 mi) ESE earthquakes near Colusa County
Mendocino County, CA 59 km (37 mi) WNW earthquakes near Mendocino County
Sonoma County, CA 89 km (55 mi) S earthquakes near Sonoma County
Sutter County, CA 97 km (60 mi) ESE earthquakes near Sutter County

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

Aftershocks so far

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

  1. 1.8 2km WNW of Redwood Valley, CA
  2. 3.7 3km WNW of Redwood Valley, CA
  3. 2.3 15km NW of Alder Springs, CA
  4. 2.9 14km NW of Alder Springs, CA
  5. 1.6 18km NW of Lake Pillsbury, CA
  6. 1.5 6km NNE of Lake Pillsbury, CA
  7. 1.8 1km N of Talmage, CA
  8. 1.6 2km N of Talmage, CA
  9. 1.7 8km W of Redwood Valley, CA
  10. 1.8 17km WNW of Lake Pillsbury, CA
  11. 2.6 20km ENE of Clearlake Oaks, CA
  12. 2.2 12km SSE of Talmage, CA
  13. 1.8 15km ESE of Lake Pillsbury, CA
  14. 1.9 15km ESE of Lake Pillsbury, CA
  15. 1.6 24km NNW of Lake Pillsbury, 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.