QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mw

5 km SSW of Petrolia, CA

· 9.9 km deep · released about 15 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 57 kmTrinity County 108 kmMendocino County 118 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
9.9 km below the surface
Felt
123 reports · strongest reported intensity V
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Nearest
Humboldt County, 57 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 278 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 123 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 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× 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 32× 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 40.2757, -124.2883. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Humboldt County, CA 57 km (35 mi) SSW of here earthquakes near Humboldt County
Trinity County, CA 108 km (67 mi) WSW of here earthquakes near Trinity County
Mendocino County, CA 118 km (74 mi) NW of here earthquakes near Mendocino County

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

Aftershocks so far

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

  1. 2.7 6 km ENE of Petrolia, CA
  2. 2.8 42 km WNW of Petrolia, CA
  3. 2.6 46 km W of Ferndale, CA
  4. 2.2 18 km W of Petrolia, CA
  5. 2.2 47 km WNW of Petrolia, CA
  6. 2.5 44 km WNW of Petrolia, CA
  7. 2.1 29 km W of Petrolia, CA
  8. 2.0 37 km WNW of Petrolia, CA
  9. 1.8 10 km W of Petrolia, CA
  10. 1.7 11 km W of Petrolia, CA
  11. 3.4 43 km WNW of Petrolia, CA
  12. 3.2 27 km W of Petrolia, CA
  13. 2.3 17 km W of Petrolia, CA
  14. 2.7 44 km WNW of Petrolia, CA
  15. 2.9 32 km W of Petrolia, 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 4,000 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.