QuakeIndex

Earthquake · reviewed by a seismologist

M 3.7ml

7 km NNW of Alderpoint, California

· 31 km deep · released about 5 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 57 kmTrinity County 64 kmMendocino County 91 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 3.7 (ml)
Depth
31 km below the surface
Felt
10 reports · strongest reported intensity IV
Measured shaking
intensity II (ShakeMap)
Nearest
Humboldt County, 57 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3441 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 10 people have reported feeling it to USGS.

How big was it?

This earthquake released about 5 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.7 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 34,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,500× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,100× the energy of this one
  4. This earthquake M 3.7 about 5 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 10× more

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 40.2385, -123.6468. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Humboldt County, CA 57 km (36 mi) SSE of here earthquakes near Humboldt County
Trinity County, CA 64 km (40 mi) SW of here earthquakes near Trinity County
Mendocino County, CA 91 km (57 mi) N of here earthquakes near Mendocino County
Glenn County, CA 128 km (79 mi) NW of here earthquakes near Glenn County
Colusa County, CA 169 km (105 mi) NW of here earthquakes near Colusa 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. 2.2 3 km ENE of Hydesville, California
  2. 2.1 21 km WSW of Weott, California
  3. 2.1 3 km W of Mad River, California
  4. 2.5 7 km SW of Scotia, California
  5. 1.8 9 km NNE of Mad River, California
  6. 1.7 3 km ENE of Garberville, California
  7. 2.1 8 km SW of Hyampom, California
  8. 1.8 10 km NNW of Mad River, California
  9. 1.7 8 km E of Redcrest, California
  10. 2.0 2 km N of Redway, California
  11. 1.9 23 km WSW of Weott, California
  12. 1.8 14 km E of Redcrest, California
  13. 1.7 19 km NNE of Redcrest, California
  14. 1.8 15 km E of Hydesville, California
  15. 1.8 17 km NE of Leggett, 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 4.5 on 2016-08-28 — it released about 16 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.