QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

9 km E of Blackhawk, CA

· 17 km deep · released about 43 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 15 kmAlameda County 24 kmSolano County 48 kmSan Joaquin County 48 kmSan Mateo County 69 kmSanta Clara County 70 kmStanislaus County 78 kmSacramento County 78 kmMarin County 85 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 2.1 (md)
Depth
17 km below the surface
Felt
no reports yet
Nearest
Contra Costa County, 15 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 794 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 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 37.8468, -121.8095. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 15 km (9 mi) ESE of here earthquakes near Contra Costa County
Alameda County, CA 24 km (15 mi) NNE of here earthquakes near Alameda County
Solano County, CA 48 km (30 mi) SSE of here earthquakes near Solano County
San Joaquin County, CA 48 km (30 mi) WSW of here earthquakes near San Joaquin County
San Mateo County, CA 69 km (43 mi) NE of here earthquakes near San Mateo County
Santa Clara County, CA 70 km (44 mi) N of here earthquakes near Santa Clara 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 3 km N of Hayward, CA
  2. 1.6 2 km NW of Alamo, CA
  3. 1.7 3 km SW of Clayton, CA
  4. 1.6 1 km ENE of Danville, CA
  5. 1.5 6 km ENE of Vallejo, CA
  6. 1.6 9 km SE of Clayton, CA
  7. 2.4 1 km NNE of Oakland, CA
  8. 3.4 8 km ENE of Alum Rock, CA
  9. 1.6 2 km NNE of San Leandro, CA
  10. 1.8 4 km SSE of Brentwood, CA
  11. 2.0 8 km ENE of Milpitas, CA
  12. 1.6 3 km SW of Clayton, CA
  13. 1.5 3 km NW of Pittsburg, CA
  14. 1.6 12 km SE of Suisun City, CA
  15. 1.5 10 km E of Blackhawk, 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 3,500 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.