QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

2 km SW of Concord, CA

· 15 km deep · released about 1,200 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 8 kmAlameda County 35 kmSolano County 36 kmMarin County 64 kmSan Joaquin County 67 kmSan Mateo County 67 kmNapa County 67 kmSacramento County 82 kmYolo County 82 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 3.1 (ml)
Depth
15 km below the surface
Felt
1120 reports · strongest reported intensity III
Nearest
Contra Costa County, 8 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 13 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 1120 people have reported feeling it to USGS.

How big was it?

This earthquake released about 1,200 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 290,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 13,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 9,100× the energy of this one
  4. This earthquake M 3.1 about 1,200 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.2× 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 37.9493, -122.0308. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 8 km (5 mi) WNW of here earthquakes near Contra Costa County
Alameda County, CA 35 km (22 mi) NNW of here earthquakes near Alameda County
Solano County, CA 36 km (23 mi) SSW of here earthquakes near Solano County
Marin County, CA 64 km (40 mi) E of here earthquakes near Marin County
San Joaquin County, CA 67 km (41 mi) W of here earthquakes near San Joaquin County
San Mateo County, CA 67 km (41 mi) NNE of here earthquakes near San Mateo County

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

Aftershocks so far

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

  1. 1.6 2 km NW of Concord, CA
  2. 1.9 5 km SSE of Pittsburg, CA
  3. 1.9 13 km NNW of Rio Vista, CA
  4. 2.3 1 km N of Sunol, CA
  5. 2.0 2 km SW of Oakland, CA
  6. 1.9 4 km SE of Sunol, CA
  7. 1.6 3 km ESE of Union City, CA
  8. 2.0 2 km E of Hayward, CA
  9. 1.5 1 km SW of Vallejo, CA
  10. 1.7 5 km WSW of Antioch, CA
  11. 1.6 2 km E of Berkeley, CA
  12. 2.0 6 km SSE of Moraga, CA
  13. 1.6 6 km SW of Clayton, CA
  14. 1.6 1 km NNW of Pleasant Hill, CA
  15. 1.9 1 km E of Hayward, 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 4.5 on 2019-10-15 — it released about 130 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.