QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

12km WNW of Alder Springs, CA

· -0.5 km deep · released about 16 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Glenn County 40 kmMendocino County 57 kmLake County 64 kmTehama County 73 kmColusa County 77 kmButte County 108 kmTrinity County 110 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
-0.5 km below the surface
Felt
no reports yet
Nearest
Glenn County, 40 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1874 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 16 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 5.8 930,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 660,000× the energy of this one
  3. Around the size people start to feel M 3.0 59× the energy of this one
  4. This earthquake M 1.8 about 16 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 39.6758, -122.8595. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Glenn County, CA 40 km (25 mi) WNW of here earthquakes near Glenn County
Mendocino County, CA 57 km (35 mi) ENE of here earthquakes near Mendocino County
Lake County, CA 64 km (40 mi) N of here earthquakes near Lake County
Tehama County, CA 73 km (46 mi) SW of here earthquakes near Tehama County
Colusa County, CA 77 km (48 mi) NW of here earthquakes near Colusa County
Butte County, CA 108 km (67 mi) W of here earthquakes near Butte County

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

Aftershocks so far

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

  1. 2.1 10km N of Lake Pillsbury, CA
  2. 1.9 12km W of Lake Pillsbury, CA
  3. 1.6 12km NW of Upper Lake, CA
  4. 1.8 14km SE of Laytonville, CA
  5. 1.7 13km E of Laytonville, CA
  6. 1.6 7km NE of Brooktrails, CA
  7. 2.8 6km E of Willits, CA
  8. 1.7 7km E of Willits, CA
  9. 2.1 9km SE of Willits, CA
  10. 1.7 8km E of Willits, CA
  11. 2.4 8km E of Willits, CA
  12. 1.5 6km E of Willits, CA
  13. 1.6 17km NW of Lake Pillsbury, CA
  14. 1.8 13km SE of Laytonville, CA
  15. 1.8 13km SE 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 80,000 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.