QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9md

Earthquake near Laytonville, CA

No earthquake was likely felt in Laytonville in the 24 hours to 8:30 pm PST (04:30 UTC). The last one was M 2.4, 13 km (8 mi) WSW, at 7:25 am PST on 4 November 2026, estimated intensity II (weak) in town. Every earthquake near Laytonville

This page: a magnitude 2.9 earthquake was recorded 27 km (17 mi) north-northwest of Laytonville, CA, at 7:28 pm PDT on 20 April 2023 (02:28 UTC), less than 1 km deep. 2 people have reported feeling it to USGS.

USGS: 27km NNW of Laytonville, CA

7:28 pm PDT, Apr 20, 2023 · · -0.6 km deep · released about 780 lb of TNT

10 km30 km60 km120 km N Mendocino County 56 kmTrinity County 89 kmHumboldt County 92 kmGlenn County 106 kmLake County 115 kmTehama County 116 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
7:28 pm PDT on 20 April 2023 ()
Where
27 km (17 mi) north-northwest of Laytonville, CA · earthquakes near Laytonville
Magnitude
M 2.9 (md)
Depth
-0.6 km below the surface
Felt
2 reports · strongest reported intensity IV
Nearest
Mendocino County, 56 km S
Nearest mapped fault
Bartlett Springs fault system, 11 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 1229 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 34 km (21 mi) from the epicentre. In Laytonville, 27 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.

Likely felt in: Laytonville 27 km, intensity II · Covelo 31 km, intensity II · Redway 31 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 780 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 19,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 14,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.2× the energy of this one
  4. This earthquake M 2.9 about 780 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 4.3 on 2022-10-20 — about 120 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 5.9 9 km S of Leggett, California · 22 km SW of this epicentre
  2. 5.5 7 km ESE of Shelter Cove, California · 38 km WNW 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 39.9245, -123.5650. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mendocino County, CA 56 km (35 mi) S earthquakes near Mendocino County
Trinity County, CA 89 km (55 mi) NNE earthquakes near Trinity County
Humboldt County, CA 92 km (57 mi) NNW earthquakes near Humboldt County
Glenn County, CA 106 km (66 mi) ESE earthquakes near Glenn County
Lake County, CA 115 km (71 mi) SE earthquakes near Lake County
Tehama County, CA 116 km (72 mi) ENE earthquakes near Tehama County

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

Aftershocks so far

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

  1. 1.9 13 km SSE of Laytonville, CA
  2. 2.3 4 km ESE of Redway, CA
  3. 1.7 13 km SSE of Laytonville, CA
  4. 2.9 14 km S of Redway, CA
  5. 2.1 15 km N of Covelo, CA
  6. 2.1 15 km N of Covelo, CA
  7. 2.3 15 km N of Covelo, CA
  8. 2.5 40 km NNE of Covelo, CA
  9. 2.0 15 km N of Covelo, CA
  10. 1.8 14 km N of Covelo, CA
  11. 1.6 15 km N of Covelo, CA
  12. 1.7 11 km SSE of Redway, CA
  13. 2.4 15 km N of Covelo, CA
  14. 1.7 8 km NNE of Laytonville, CA
  15. 1.8 15 km N of Covelo, 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.