QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

9 km ENE of Blackhawk, CA

· 16 km deep · released about 1,400 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 13 kmAlameda County 25 kmSolano County 46 kmSan Joaquin County 49 kmSan Mateo County 70 kmSanta Clara County 72 kmSacramento County 77 kmStanislaus County 79 kmMarin County 84 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
16 km below the surface
Felt
257 reports · strongest reported intensity III
Nearest
Contra Costa County, 13 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 5 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 257 people have reported feeling it to USGS.

How big was it?

This earthquake released about 1,400 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 6.7 230,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 10,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 7,400× the energy of this one
  4. This earthquake M 3.1 about 1,400 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.5× 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 37.8628, -121.8208. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 13 km (8 mi) ESE of here earthquakes near Contra Costa County
Alameda County, CA 25 km (16 mi) NNE of here earthquakes near Alameda County
Solano County, CA 46 km (29 mi) SSE of here earthquakes near Solano County
San Joaquin County, CA 49 km (30 mi) W of here earthquakes near San Joaquin County
San Mateo County, CA 70 km (43 mi) NE of here earthquakes near San Mateo County
Santa Clara County, CA 72 km (45 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

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

  1. 1.6 3 km SW of San Ramon, CA
  2. 1.1 8 km SSE of Sunol, CA
  3. 1.2 8 km SSE of Sunol, CA
  4. 2.3 4 km WNW of Orinda, CA
  5. 2.2 1 km E of Port Costa, CA
  6. 1.7 12 km SE of Livermore, CA
  7. 1.4 12 km SE of Livermore, CA
  8. 1.1 2 km NE of Danville, CA
  9. 1.4 12 km SE of Livermore, CA
  10. 1.1 13 km SE of Livermore, CA
  11. 0.9 20 km NE of Alum Rock, CA
  12. 1.4 4 km NNW of San Leandro, CA
  13. 2.0 9 km ESE of Livermore, CA
  14. 1.7 2 km NNE of Pleasant Hill, CA
  15. 2.5 10 km ENE of Milpitas, 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 100 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.