QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5md

4km NNE of Blackhawk, CA

· 8.4 km deep · released about 170 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 10 kmAlameda County 22 kmSolano County 47 kmSan Joaquin County 55 kmSan Mateo County 64 kmSanta Clara County 72 kmMarin County 79 kmSacramento County 82 kmNapa County 83 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 2.5 (md)
Depth
8.4 km below the surface
Felt
32 reports · strongest reported intensity IV
Nearest
Contra Costa County, 10 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1809 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 32 people have reported feeling it to USGS.

How big was it?

This earthquake released about 170 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 89,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 63,000× the energy of this one
  3. Around the size people start to feel M 3.0 5.6× the energy of this one
  4. This earthquake M 2.5 about 170 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 37.8478, -121.8848. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 10 km (6 mi) SE of here earthquakes near Contra Costa County
Alameda County, CA 22 km (14 mi) N of here earthquakes near Alameda County
Solano County, CA 47 km (29 mi) S of here earthquakes near Solano County
San Joaquin County, CA 55 km (34 mi) W of here earthquakes near San Joaquin County
San Mateo County, CA 64 km (40 mi) NE of here earthquakes near San Mateo County
Santa Clara County, CA 72 km (45 mi) NNW 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

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

  1. 2.8 4km ENE of El Sobrante, CA
  2. 2.1 4km ENE of El Sobrante, CA
  3. 1.6 10km NE of Milpitas, CA
  4. 1.5 3km SSW of Clayton, CA
  5. 1.9 1km S of San Ramon, CA
  6. 1.6 9km SE of Sunol, CA
  7. 1.6 5km SW of Clayton, CA
  8. 2.8 16km SSE of Livermore, CA
  9. 1.6 6km E of Vallejo, CA
  10. 2.1 3km WNW of Crockett, CA
  11. 2.1 4km WSW of Alamo, CA
  12. 2.1 6km SSW of Moraga, CA
  13. 1.9 5km SW of Pacheco, CA
  14. 1.8 2km SE of Pacheco, CA
  15. 1.6 1km S 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 870 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.