QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mw

near the coast of Northern California

· 9.1 km deep · released about 17 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 56 kmTrinity County 108 kmMendocino County 120 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
9.1 km below the surface
Felt
419 reports · strongest reported intensity V
Measured shaking
intensity V (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Humboldt County, 56 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3111 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 419 people have reported feeling it to USGS.

How big was it?

This earthquake released about 17 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 10,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 450× the energy of this one
  3. Magna, Utah 2020 M 5.7 320× the energy of this one
  4. This earthquake M 4.0 about 17 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 35× 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 40.2878, -124.2988. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Humboldt County, CA 56 km (35 mi) SW of here earthquakes near Humboldt County
Trinity County, CA 108 km (67 mi) WSW of here earthquakes near Trinity County
Mendocino County, CA 120 km (75 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. 2.2 near the coast of Northern California
  2. 2.0 9 km SSW of Ferndale, California
  3. 2.8 9 km SW of Ferndale, California
  4. 2.4 9 km SW of Ferndale, California
  5. 2.7 9 km SSW of Ferndale, California
  6. 2.7 51 km SW of Ferndale, California
  7. 2.2 8 km NNE of Redcrest, California
  8. 1.9 4 km SSW of Redcrest, California
  9. 1.8 26 km SSW of Scotia, California
  10. 1.9 10 km W of Rio Dell, California
  11. 2.1 10 km WSW of Rio Dell, California
  12. 2.2 25 km SW of Scotia, California
  13. 2.8 25 km SW of Scotia, California
  14. 2.5 25 km SW of Scotia, California
  15. 2.3 23 km WSW of Weott, 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 4.4 on 2016-01-02 — it released about 4.1 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.