QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

9km E of Blackhawk, CA

· 13 km deep · released about 13 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 17 kmAlameda County 21 kmSan Joaquin County 49 kmSolano County 51 kmSan Mateo County 67 kmSanta Clara County 67 kmStanislaus County 76 kmSacramento County 81 kmMarin County 86 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 1.8 (md)
Depth
13 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 1948 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 13 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 810,000× the energy of this one
  3. Around the size people start to feel M 3.0 72× the energy of this one
  4. This earthquake M 1.8 about 13 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 37.8193, -121.8053. 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 21 km (13 mi) NNE of here earthquakes near Alameda County
San Joaquin County, CA 49 km (30 mi) WSW of here earthquakes near San Joaquin County
Solano County, CA 51 km (32 mi) SSE of here earthquakes near Solano County
San Mateo County, CA 67 km (42 mi) NE of here earthquakes near San Mateo County
Santa Clara County, CA 67 km (42 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. 1.6 5km E of Vallejo, CA
  2. 1.9 10km NE of Milpitas, CA
  3. 1.7 5km NW of Dublin, CA
  4. 2.6 6km S of Livermore, CA
  5. 2.4 11km NE of Milpitas, CA
  6. 1.8 5km ENE of Vallejo, CA
  7. 1.7 8km SSW of Livermore, CA
  8. 1.8 3km SW of Alamo, CA
  9. 1.9 3km SW of Clayton, CA
  10. 1.8 1km ENE of Alamo, CA
  11. 1.7 5km WNW of Dublin, CA
  12. 1.5 5km E of Fremont, CA
  13. 1.6 1km NE of Berkeley, CA
  14. 2.1 8km ENE of Alum Rock, CA
  15. 2.0 1km NNW of Pleasant Hill, 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 11,000 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.