QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9mw

7km WNW of Cobb, CA

· 2.9 km deep · released about 10 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lake County 31 kmSonoma County 36 kmNapa County 55 kmColusa County 62 kmYolo County 79 kmMendocino County 87 kmMarin County 87 kmGlenn County 92 kmSutter County 97 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 3.9 (mw)
Depth
2.9 km below the surface
Felt
82 reports · strongest reported intensity VI
Measured shaking
intensity VI (ShakeMap)
Nearest
Lake County, 31 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2588 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 82 people have reported feeling it to USGS.

How big was it?

This earthquake released about 10 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 17,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 760× the energy of this one
  3. Magna, Utah 2020 M 5.7 540× the energy of this one
  4. This earthquake M 3.9 about 10 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 21× 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 38.8337, -122.7973. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Lake County, CA 31 km (19 mi) S of here earthquakes near Lake County
Sonoma County, CA 36 km (22 mi) NNE of here earthquakes near Sonoma County
Napa County, CA 55 km (34 mi) NW of here earthquakes near Napa County
Colusa County, CA 62 km (38 mi) SW of here earthquakes near Colusa County
Yolo County, CA 79 km (49 mi) WNW of here earthquakes near Yolo County
Mendocino County, CA 87 km (54 mi) SE of here earthquakes near Mendocino County

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

Aftershocks so far

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

  1. 1.6 10km NW of The Geysers, CA
  2. 1.7 13km ENE of Cloverdale, CA
  3. 2.0 4km W of Cobb, CA
  4. 2.0 2km NW of The Geysers, CA
  5. 2.5 7km WNW of The Geysers, CA
  6. 3.2 13km W of Lakeport, CA
  7. 1.7 7km N of Kenwood, CA
  8. 1.7 12km WNW of The Geysers, CA
  9. 1.6 3km W of Cobb, CA
  10. 2.0 2km SSW of Anderson Springs, CA
  11. 2.3 4km SW of Anderson Springs, CA
  12. 2.5 2km NW of The Geysers, CA
  13. 1.9 6km WNW of The Geysers, CA
  14. 1.7 6km NNW of The Geysers, CA
  15. 2.4 3km W of Cobb, 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 5.0 on 2016-12-14 — it released about 50 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.