QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

4km WNW of Mountain House, CA

· 3.2 km deep · released about 40 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Joaquin County 31 kmAlameda County 33 kmContra Costa County 35 kmStanislaus County 58 kmSolano County 61 kmSanta Clara County 65 kmSacramento County 75 kmSan Mateo County 81 kmSanta Cruz County 95 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 2.1 (md)
Depth
3.2 km below the surface
Felt
no reports yet
Nearest
San Joaquin County, 31 km ENE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2664 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 40 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 380,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 270,000× the energy of this one
  3. Around the size people start to feel M 3.0 24× the energy of this one
  4. This earthquake M 2.1 about 40 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 37.7997, -121.5845. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Joaquin County, CA 31 km (19 mi) WSW of here earthquakes near San Joaquin County
Alameda County, CA 33 km (21 mi) ENE of here earthquakes near Alameda County
Contra Costa County, CA 35 km (22 mi) ESE of here earthquakes near Contra Costa County
Stanislaus County, CA 58 km (36 mi) WNW of here earthquakes near Stanislaus County
Solano County, CA 61 km (38 mi) SSE of here earthquakes near Solano County
Santa Clara County, CA 65 km (40 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

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

  1. 1.6 4km NNE of Dublin, CA
  2. 1.6 4km N of Dublin, CA
  3. 1.6 4km NNE of Dublin, CA
  4. 2.2 4km N of Dublin, CA
  5. 2.8 4km N of Dublin, CA
  6. 1.8 4km NNE of Dublin, CA
  7. 1.6 4km NNE of Dublin, CA
  8. 2.6 4km NNE of Dublin, CA
  9. 1.6 3km SW of Clayton, CA
  10. 1.6 4km N of Dublin, CA
  11. 1.6 4km NNE of Dublin, CA
  12. 1.6 4km NNE of Dublin, CA
  13. 2.0 4km N of Dublin, CA
  14. 1.9 4km N of Dublin, CA
  15. 1.8 4km NNE of Dublin, 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.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.