QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

10 km E of Blackhawk, CA

· 20 km deep · released about 19 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 17 kmAlameda County 22 kmSan Joaquin County 48 kmSolano County 51 kmSanta Clara County 68 kmSan Mateo County 68 kmStanislaus County 76 kmSacramento County 80 kmMarin County 87 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 1.9 (md)
Depth
20 km below the surface
Felt
no reports yet
Nearest
Contra Costa County, 17 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 145 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 19 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 790,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 560,000× the energy of this one
  3. Around the size people start to feel M 3.0 50× the energy of this one
  4. This earthquake M 1.9 about 19 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 37.8263, -121.7980. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 17 km (11 mi) SE of here earthquakes near Contra Costa County
Alameda County, CA 22 km (14 mi) NNE of here earthquakes near Alameda County
San Joaquin County, CA 48 km (30 mi) WSW of here earthquakes near San Joaquin County
Solano County, CA 51 km (31 mi) SSE of here earthquakes near Solano County
Santa Clara County, CA 68 km (42 mi) N of here earthquakes near Santa Clara County
San Mateo County, CA 68 km (42 mi) NE 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

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

  1. 1.8 2 km SW of Alamo, CA
  2. 1.7 2 km ESE of Pacheco, CA
  3. 2.2 8 km NE of Alum Rock, CA
  4. 1.9 2 km SE of Oakland, CA
  5. 2.0 2 km ENE of Berkeley, CA
  6. 2.6 2 km NNE of San Leandro, CA
  7. 1.5 3 km SW of Clayton, CA
  8. 1.9 2 km ESE of Pacheco, CA
  9. 1.8 4 km S of Pittsburg, CA
  10. 1.8 2 km SW of Alamo, CA
  11. 1.9 6 km NE of Alamo, CA
  12. 2.0 12 km SE of Sunol, CA
  13. 2.0 2 km ENE of Hayward, CA
  14. 1.6 9 km ENE of Blackhawk, CA
  15. 1.7 3 km SW of Clayton, 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 7,700 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.