QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

18 km S of Hayfork, CA

· 9.1 km deep · released about 13 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Trinity County 29 kmHumboldt County 71 kmTehama County 87 kmShasta County 105 kmMendocino County 109 kmGlenn County 111 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
9.1 km below the surface
Felt
no reports yet
Nearest
Trinity County, 29 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 276 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 13 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 1,200,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 840,000× the energy of this one
  3. Around the size people start to feel M 3.0 75× the energy of this one
  4. This earthquake M 1.8 about 13 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 40.3930, -123.1910. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Trinity County, CA 29 km (18 mi) SSW of here earthquakes near Trinity County
Humboldt County, CA 71 km (44 mi) ESE of here earthquakes near Humboldt County
Tehama County, CA 87 km (54 mi) WNW of here earthquakes near Tehama County
Shasta County, CA 105 km (65 mi) WSW of here earthquakes near Shasta County
Mendocino County, CA 109 km (68 mi) NNE of here earthquakes near Mendocino County
Glenn County, CA 111 km (69 mi) NW of here earthquakes near Glenn County

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

Aftershocks so far

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

  1. 3.7 36 km E of Hydesville, CA
  2. 1.7 29 km WSW of Hayfork, CA
  3. 2.7 32 km NNW of Covelo, CA
  4. 2.6 32 km NW of Covelo, CA
  5. 1.6 41 km WNW of Rancho Tehama Reserve, CA
  6. 3.2 31 km NNW of Covelo, CA
  7. 2.2 30 km NNW of Covelo, CA
  8. 1.5 29 km NW of Covelo, CA
  9. 1.8 30 km NNW of Covelo, CA
  10. 4.4 31 km NNW of Covelo, CA
  11. 3.9 31 km NNW of Covelo, CA
  12. 1.5 31 km NW of Covelo, CA
  13. 4.0 31 km NNW of Covelo, CA
  14. 1.9 29 km NE of Redway, CA
  15. 2.1 34 km NE of Redway, 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 4.5 on 2016-08-28 — it released about 13,000 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.