QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9ml

12 km WSW of Mad River, California

· 22 km deep · released about 680 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 39 kmTrinity County 52 kmMendocino 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 2.9 (ml)
Depth
22 km below the surface
Felt
2 reports · strongest reported intensity II
Nearest
Humboldt County, 39 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3427 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 2 people have reported feeling it to USGS.

How big was it?

This earthquake released about 680 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 22,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 16,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.4× the energy of this one
  4. This earthquake M 2.9 about 680 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 40.4197, -123.6545. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Humboldt County, CA 39 km (24 mi) SE of here earthquakes near Humboldt County
Trinity County, CA 52 km (32 mi) WSW of here earthquakes near Trinity County
Mendocino County, CA 111 km (69 mi) N of here earthquakes near Mendocino County
Glenn County, CA 140 km (87 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

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

  1. 2.7 1km ENE of Hayfork, CA
  2. 2.0 42km S of Hayfork, CA
  3. 2.0 31km SW of Hayfork, CA
  4. 2.8 5km NE of Hydesville, CA
  5. 1.8 15km ESE of Hydesville, CA
  6. 1.9 1km NE of Redway, CA
  7. 2.1 24km SE of Willow Creek, CA
  8. 1.8 38km SSW of Hayfork, CA
  9. 2.1 15km S of Willow Creek, CA
  10. 2.5 16 km WSW of Burnt Ranch, California
  11. 1.8 17 km WSW of Mad River, California
  12. 2.2 6 km W of Burnt Ranch, California
  13. 2.2 8 km NNE of Redcrest, California
  14. 1.9 4 km SSW of Redcrest, California
  15. 2.3 9 km ESE of Burnt Ranch, California

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 4.8 on 2016-07-21 — it released about 730 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.