QuakeIndex

Earthquake · reviewed by a seismologist

M 4.1mw

9km W of Rio Dell, CA

· 21 km deep · released about 19 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 34 kmTrinity County 94 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 4.1 (mw)
Depth
21 km below the surface
Felt
246 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Nearest
Humboldt County, 34 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1569 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 246 people have reported feeling it to USGS.

How big was it?

This earthquake released about 19 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 8,800× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 390× the energy of this one
  3. Magna, Utah 2020 M 5.7 280× the energy of this one
  4. This earthquake M 4.1 about 19 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 40× 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 40.4872, -124.2102. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Humboldt County, CA 34 km (21 mi) SW of here earthquakes near Humboldt County
Trinity County, CA 94 km (59 mi) W of here earthquakes near Trinity County
Mendocino County, CA 134 km (83 mi) NNW of here earthquakes near Mendocino 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. 1.7 12km SSW of Ferndale, CA
  2. 2.0 19km SE of Petrolia, CA
  3. 2.0 19km SE of Petrolia, CA
  4. 2.2 2km ESE of Hydesville, CA
  5. 2.1 8km S of Ferndale, CA
  6. 1.7 10km SSW of Ferndale, CA
  7. 1.8 12km SSW of Ferndale, CA
  8. 2.5 14km WSW of Petrolia, CA
  9. 2.6 33km W of Petrolia, CA
  10. 2.6 6km NNW of Petrolia, CA
  11. 2.0 22km W of Petrolia, CA
  12. 2.3 11km SSW of Ferndale, CA
  13. 2.2 4km W of Humboldt Hill, CA
  14. 1.6 10km SSW of Ferndale, CA
  15. 2.4 22km SE of Blue Lake, 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 6.2 on 2021-12-20 — it released about 1,600 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.