QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

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 1.7 earthquake was recorded 40 km (25 mi) east-northeast of Ukiah, CA, at 5:05 pm PDT on 12 July 2018 (00:05 UTC), 6.3 km deep.

USGS: 18km SE of Lake Pillsbury, CA

5:05 pm PDT, Jul 12, 2018 · · 6.3 km deep · released about 10 lb of TNT

10 km30 km60 km120 km N Lake County 23 kmGlenn County 47 kmColusa County 50 kmMendocino County 57 kmSonoma County 88 kmNapa County 98 kmSutter County 99 kmTehama County 103 kmYolo County 104 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
5:05 pm PDT on 12 July 2018 ()
Where
40 km (25 mi) east-northeast of Ukiah, CA · earthquakes near Ukiah
Magnitude
M 1.7 (md)
Depth
6.3 km below the surface
Felt
no reports yet
Nearest
Lake County, 23 km S
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 3044 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 10 km (6 mi) from the epicentre. In Ukiah, 40 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 10 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 1,500,000× 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 95× the energy of this one
  4. This earthquake M 1.7 about 10 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 130,000 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 · 34 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 39.3103, -122.7950. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, CA 23 km (14 mi) S earthquakes near Lake County
Glenn County, CA 47 km (29 mi) NE earthquakes near Glenn County
Colusa County, CA 50 km (31 mi) ESE earthquakes near Colusa County
Mendocino County, CA 57 km (36 mi) WNW earthquakes near Mendocino County
Sonoma County, CA 88 km (55 mi) S earthquakes near Sonoma County
Napa County, CA 98 km (61 mi) SSE earthquakes near Napa County

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

Aftershocks so far

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

  1. 2.4 9km ESE of Willits, CA
  2. 1.8 4km SSE of Lake Pillsbury, CA
  3. 2.5 8km ESE of Willits, CA
  4. 2.0 9km ESE of Willits, CA
  5. 2.1 12km SW of Lake Pillsbury, CA
  6. 1.8 15km NW of Alder Springs, CA
  7. 2.0 8km NNW of Redwood Valley, CA
  8. 2.2 13km ENE of Redwood Valley, CA
  9. 1.9 3km NW of Redwood Valley, CA
  10. 1.5 9km WNW of Cobb, CA
  11. 1.9 9km SW of Kelseyville, CA
  12. 1.8 8km SW of Kelseyville, CA
  13. 1.9 17km SE of Lake Pillsbury, CA
  14. 1.9 17km ESE of Lake Pillsbury, CA
  15. 1.9 8km SSE 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.