QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mw

6km NNE of Hydesville, CA

· 23 km deep · released about 15 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 17 kmTrinity County 81 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 4.0 (mw)
Depth
23 km below the surface
Felt
50 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Nearest
Humboldt County, 17 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1307 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 50 people have reported feeling it to USGS.

How big was it?

This earthquake released about 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 12,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 520× the energy of this one
  3. Magna, Utah 2020 M 5.7 370× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 31× 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 40.6005, -124.0688. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Humboldt County, CA 17 km (10 mi) SW of here earthquakes near Humboldt County
Trinity County, CA 81 km (50 mi) W of here earthquakes near Trinity County

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

Aftershocks so far

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

  1. 2.3 3km SE of Ferndale, CA
  2. 2.2 10km NNE of Hydesville, CA
  3. 2.2 5km SE of Ferndale, CA
  4. 2.0 16km WSW of Ferndale, CA
  5. 2.5 14km WSW of Ferndale, CA
  6. 3.0 19km WSW of Ferndale, CA
  7. 2.4 7km WSW of Ferndale, CA
  8. 2.7 3km ENE of Hydesville, CA
  9. 1.8 9km E of Hydesville, CA
  10. 2.0 7km SW of Ferndale, CA
  11. 1.7 14km ENE of Hydesville, CA
  12. 1.8 2km NW of Hydesville, CA
  13. 2.6 7km SW of Ferndale, CA
  14. 1.8 6km SW of Ferndale, CA
  15. 4.3 6km WSW of Ferndale, 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 6.4 on 2022-12-20 — it released about 4,100 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.