QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

3km S of Concord, CA

· 10 km deep · released about 14 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 7 kmAlameda County 34 kmSolano County 37 kmMarin County 65 kmSan Joaquin County 66 kmSan Mateo County 66 kmNapa County 68 kmSacramento County 82 kmYolo 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 1.8 (md)
Depth
10 km below the surface
Felt
no reports yet
Nearest
Contra Costa County, 7 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1982 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 14 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 5.7 760,000× the energy of this one
  3. Around the size people start to feel M 3.0 68× the energy of this one
  4. This earthquake M 1.8 about 14 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 37.9417, -122.0202. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 7 km (4 mi) WNW of here earthquakes near Contra Costa County
Alameda County, CA 34 km (21 mi) NNW of here earthquakes near Alameda County
Solano County, CA 37 km (23 mi) S of here earthquakes near Solano County
Marin County, CA 65 km (40 mi) E of here earthquakes near Marin County
San Joaquin County, CA 66 km (41 mi) W of here earthquakes near San Joaquin County
San Mateo County, CA 66 km (41 mi) NNE 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

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

  1. 1.5 4km E of Moraga, CA
  2. 2.2 4km NNE of Blackhawk, CA
  3. 2.5 4km NNE of Blackhawk, CA
  4. 2.0 4km NE of Blackhawk, CA
  5. 1.6 9km WSW of Mountain House, CA
  6. 2.3 2km WNW of Concord, CA
  7. 1.7 2km E of Berkeley, CA
  8. 1.8 5km E of Fremont, CA
  9. 1.7 3km NNW of Byron, CA
  10. 1.6 3km NNW of Piedmont, CA
  11. 2.1 2km ENE of Berkeley, CA
  12. 1.7 3km WNW of Castro Valley, CA
  13. 1.9 1km NNW of Crockett, CA
  14. 2.7 6km SSW of San Ramon, CA
  15. 3.9 3km N of San Lorenzo, 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 10,000 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.