QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mw

6 km SW of Cobb, California

· 2.8 km deep · released about 14 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sonoma County 32 kmLake County 36 kmNapa County 50 kmColusa County 64 kmYolo County 77 kmMarin County 82 kmMendocino County 92 kmSolano County 93 kmGlenn County 96 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
2.8 km below the surface
Felt
85 reports · strongest reported intensity V
Measured shaking
intensity V (ShakeMap)
Nearest
Sonoma County, 32 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3347 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 85 people have reported feeling it to USGS.

How big was it?

This earthquake released about 14 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 5.8 540× the energy of this one
  3. Magna, Utah 2020 M 5.7 380× the energy of this one
  4. This earthquake M 4.0 about 14 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 30× 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 38.7883, -122.7772. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Sonoma County, CA 32 km (20 mi) NNE of here earthquakes near Sonoma County
Lake County, CA 36 km (22 mi) S of here earthquakes near Lake County
Napa County, CA 50 km (31 mi) NW of here earthquakes near Napa County
Colusa County, CA 64 km (40 mi) SW of here earthquakes near Colusa County
Yolo County, CA 77 km (48 mi) W of here earthquakes near Yolo County
Marin County, CA 82 km (51 mi) N of here earthquakes near Marin 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. 2.6 7 km S of Cobb, California
  2. 2.3 6 km W of Cobb, California
  3. 1.6 11 km W of Cobb, California
  4. 2.2 11 km W of Cobb, California
  5. 1.5 8 km W of Cobb, California
  6. 1.7 6 km WSW of Hopland, California
  7. 2.0 5 km SW of Cobb, California
  8. 2.2 8 km W of Cobb, California
  9. 1.6 15 km NE of Lucerne, California
  10. 2.0 15 km NE of Lucerne, California
  11. 1.5 7 km W of Cobb, California
  12. 1.7 8 km WSW of Cobb, California
  13. 1.6 4 km W of Cobb, California
  14. 1.7 5 km S of Cobb, California
  15. 1.5 6 km W of Cobb, 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 5.0 on 2016-12-14 — it released about 35 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.