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, 5 km (3 mi) E of Ukiah, at 3:26 am PST on 12 November 2026 (11:26 UTC); the estimated shaking in Ukiah was intensity II (weak). Every earthquake near Ukiah

This page: a magnitude 1.7 earthquake was recorded 39 km (24 mi) northeast of Ukiah, CA, at 1:07 am PDT on 20 March 2018 (08:07 UTC), 14 km deep.

USGS: 5km E of Lake Pillsbury, CA

1:07 am PDT, Mar 20, 2018 · · 14 km deep · released about 9.6 lb of TNT

10 km30 km60 km120 km N Lake County 35 kmMendocino County 47 kmGlenn County 48 kmColusa County 62 kmSonoma County 98 kmTehama County 98 kmSutter County 111 kmNapa County 111 kmButte County 115 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
1:07 am PDT on 20 March 2018 ()
Where
39 km (24 mi) northeast of Ukiah, CA · earthquakes near Ukiah
Magnitude
M 1.7 (md)
Depth
14 km below the surface
Felt
no reports yet
Nearest
Lake County, 35 km SSE
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 3158 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, 39 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.

How big was it?

This earthquake released about 9.6 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 1,600,000× 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 99× the energy of this one
  4. This earthquake M 1.7 about 9.6 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 · 36 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 39.4037, -122.8963. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, CA 35 km (22 mi) SSE earthquakes near Lake County
Mendocino County, CA 47 km (29 mi) W earthquakes near Mendocino County
Glenn County, CA 48 km (30 mi) ENE earthquakes near Glenn County
Colusa County, CA 62 km (39 mi) ESE earthquakes near Colusa County
Sonoma County, CA 98 km (61 mi) S earthquakes near Sonoma County
Tehama County, CA 98 km (61 mi) NE earthquakes near Tehama County

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

Aftershocks so far

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

  1. 1.8 6km SE of Lake Pillsbury, CA
  2. 1.9 18km NE of Upper Lake, CA
  3. 1.9 17km NE of Upper Lake, CA
  4. 1.6 13km WSW of Lakeport, CA
  5. 1.8 17km NE of Nice, CA
  6. 2.0 4km NW of Redwood Valley, CA
  7. 1.6 7km SW of Lakeport, CA
  8. 1.9 2km WNW of Redwood Valley, CA
  9. 1.8 2km WNW of Redwood Valley, CA
  10. 3.7 3km WNW of Redwood Valley, CA
  11. 2.3 15km NW of Alder Springs, CA
  12. 2.9 14km NW of Alder Springs, CA
  13. 1.6 18km NW of Lake Pillsbury, CA
  14. 1.5 6km NNE of Lake Pillsbury, CA
  15. 1.8 1km N of Talmage, 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.