QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

5km E of Blackhawk, CA

· 15 km deep · released about 7.8 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 15 kmAlameda County 19 kmSolano County 51 kmSan Joaquin County 53 kmSan Mateo County 64 kmSanta Clara County 67 kmStanislaus County 80 kmMarin County 83 kmSacramento 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 1.6 (md)
Depth
15 km below the surface
Felt
2 reports · strongest reported intensity II
Nearest
Contra Costa County, 15 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1566 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 2 people have reported feeling it to USGS.

How big was it?

This earthquake released about 7.8 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,900,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
  3. Around the size people start to feel M 3.0 120× the energy of this one
  4. This earthquake M 1.6 about 7.8 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 37.8120, -121.8512. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 15 km (9 mi) SE of here earthquakes near Contra Costa County
Alameda County, CA 19 km (12 mi) NNE of here earthquakes near Alameda County
Solano County, CA 51 km (32 mi) S of here earthquakes near Solano County
San Joaquin County, CA 53 km (33 mi) WSW 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 67 km (42 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

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

  1. 1.6 11km NE of Milpitas, CA
  2. 2.2 10km SE of Sunol, CA
  3. 2.1 10km ESE of Fremont, CA
  4. 1.8 24km SSE of Livermore, CA
  5. 1.9 8km WSW of Mountain House, CA
  6. 3.4 24km NE of Alum Rock, CA
  7. 2.1 6km NW of Bay Point, CA
  8. 1.9 2km ENE of Berkeley, CA
  9. 1.6 6km SSW of Suisun City, CA
  10. 1.8 2km SE of Pacheco, CA
  11. 1.7 3km ESE of Berkeley, CA
  12. 2.0 3km ESE of Berkeley, CA
  13. 1.7 5km E of Vallejo, CA
  14. 2.4 3km ESE of Berkeley, CA
  15. 2.9 3km ESE of Berkeley, 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 19,000 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.