QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9ml

9 km S of Cobb, California

· 2.5 km deep · released about 720 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sonoma County 29 kmLake County 41 kmNapa County 43 kmColusa County 65 kmYolo County 72 kmMarin County 77 kmSolano County 86 kmSutter County 95 kmMendocino County 99 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 2.9 (ml)
Depth
2.5 km below the surface
Felt
10 reports · strongest reported intensity III
Nearest
Sonoma County, 29 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3338 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 10 people have reported feeling it to USGS.

How big was it?

This earthquake released about 720 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 21,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 15,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.3× the energy of this one
  4. This earthquake M 2.9 about 720 lb of TNT

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 38.7398, -122.7277. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Sonoma County, CA 29 km (18 mi) NE of here earthquakes near Sonoma County
Lake County, CA 41 km (25 mi) S of here earthquakes near Lake County
Napa County, CA 43 km (27 mi) NW of here earthquakes near Napa County
Colusa County, CA 65 km (40 mi) SW of here earthquakes near Colusa County
Yolo County, CA 72 km (45 mi) W of here earthquakes near Yolo County
Marin County, CA 77 km (48 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

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

  1. 1.8 7 km WSW of Cobb, California
  2. 1.5 7 km W of Cobb, California
  3. 1.8 6 km W of Cobb, California
  4. 1.8 9 km WNW of Cobb, California
  5. 1.6 3 km S of Cobb, California
  6. 1.5 7 km ESE of Hopland, California
  7. 1.6 5 km W of Cobb, California
  8. 3.5 11 km WNW of Calistoga, California
  9. 1.9 4 km W of Cobb, California
  10. 1.8 6 km W of Cobb, California
  11. 1.7 Northern California
  12. 1.7 5 km S of Cobb, California
  13. 1.6 5 km WNW of Cobb, California
  14. 1.6 5 km SSW of Cobb, California
  15. 1.9 4 km SSW 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 1,400 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.