QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

23km WNW of Alder Springs, CA

· 1.3 km deep · released about 15 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Mendocino County 50 kmGlenn County 51 kmLake County 70 kmTehama County 79 kmColusa County 87 kmTrinity County 105 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
Magnitude
M 1.8 (md)
Depth
1.3 km below the surface
Felt
no reports yet
Nearest
Mendocino County, 50 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2514 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 730,000× the energy of this one
  3. Around the size people start to feel M 3.0 65× the energy of this one
  4. This earthquake M 1.8 about 15 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.

Where

Epicentre 39.7132, -122.9837. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Mendocino County, CA 50 km (31 mi) NE of here earthquakes near Mendocino County
Glenn County, CA 51 km (32 mi) WNW of here earthquakes near Glenn County
Lake County, CA 70 km (44 mi) NNW of here earthquakes near Lake County
Tehama County, CA 79 km (49 mi) SW of here earthquakes near Tehama County
Colusa County, CA 87 km (54 mi) NW of here earthquakes near Colusa County
Trinity County, CA 105 km (65 mi) S of here earthquakes near Trinity County

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

Aftershocks so far

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

  1. 1.5 9km E of Willits, CA
  2. 1.6 10km ESE of Willits, CA
  3. 1.9 12km NNW of Covelo, CA
  4. 1.6 11km NNW of Covelo, CA
  5. 1.6 11km NNW of Covelo, CA
  6. 1.6 13km WNW of Alder Springs, CA
  7. 1.6 16km N of Lake Pillsbury, CA
  8. 1.9 5km NNE of Alder Springs, CA
  9. 3.1 6km SE of Laytonville, CA
  10. 1.6 11km NNW of Covelo, CA
  11. 2.4 12km NNW of Covelo, CA
  12. 1.8 15km N of Laytonville, CA
  13. 1.8 14km NE of Covelo, CA
  14. 1.5 16km N of Lake Pillsbury, CA
  15. 2.0 16km N of Laytonville, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 5.1 on 2016-08-10 — it released about 89,000 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.