QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

3 km NNW of Castro Valley, California

· 11 km deep · released about 49 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alameda County 19 kmContra Costa County 25 kmSan Mateo County 42 kmSolano County 62 kmSanta Clara County 67 kmMarin County 67 kmSan Joaquin County 76 kmSanta Cruz County 80 kmSan Francisco County 82 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
11 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Alameda County, 19 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3515 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 49 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 5.8 310,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 220,000× the energy of this one
  3. Around the size people start to feel M 3.0 19× the energy of this one
  4. This earthquake M 2.1 about 49 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 37.7257, -122.0983. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Alameda County, CA 19 km (12 mi) WNW of here earthquakes near Alameda County
Contra Costa County, CA 25 km (16 mi) SSW of here earthquakes near Contra Costa County
San Mateo County, CA 42 km (26 mi) NE of here earthquakes near San Mateo County
Solano County, CA 62 km (38 mi) SSW of here earthquakes near Solano County
Santa Clara County, CA 67 km (41 mi) NNW of here earthquakes near Santa Clara County
Marin County, CA 67 km (42 mi) ESE of here earthquakes near Marin County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

  1. 2.0 5 km WSW of Martinez, California
  2. 1.7 1 km N of Pacifica, California
  3. 1.7 4 km S of Pittsburg, California
  4. 1.5 1 km S of Livermore, California
  5. 2.1 8 km N of East Foothills, California
  6. 2.8 8 km SE of Livermore, California
  7. 1.6 2 km ESE of Waldon, California
  8. 1.8 9 km SW of Brentwood, California
  9. 2.2 1 km ENE of Pacifica, California
  10. 1.5 0 km NW of Concord, California
  11. 1.8 5 km NE of East Foothills, California
  12. 2.6 Northern California
  13. 2.1 6 km E of East Foothills, California
  14. 1.6 1 km S of Pacheco, California
  15. 2.2 1 km E of Pacheco, California

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.