QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

10 km NNE of Milpitas, CA

· 8.5 km deep · released about 44 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alameda County 16 kmSanta Clara County 36 kmSan Mateo County 46 kmContra Costa County 46 kmSanta Cruz County 56 kmSan Joaquin County 71 kmStanislaus County 77 kmSolano County 85 kmMarin County 98 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
8.5 km below the surface
Felt
5 reports · strongest reported intensity III
Nearest
Alameda County, 16 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 898 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 5 people have reported feeling it to USGS.

How big was it?

This earthquake released about 44 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 5.8 340,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 240,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 44 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 37.5083, -121.8693. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Alameda County, CA 16 km (10 mi) SSE of here earthquakes near Alameda County
Santa Clara County, CA 36 km (22 mi) NNW of here earthquakes near Santa Clara County
San Mateo County, CA 46 km (28 mi) ENE of here earthquakes near San Mateo County
Contra Costa County, CA 46 km (29 mi) S of here earthquakes near Contra Costa County
Santa Cruz County, CA 56 km (35 mi) NNE of here earthquakes near Santa Cruz County
San Joaquin County, CA 71 km (44 mi) SW of here earthquakes near San Joaquin County

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

Aftershocks so far

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

  1. 3.0 14 km NNE of Morgan Hill, CA
  2. 1.8 7 km SE of Fremont, CA
  3. 2.1 4 km E of Union City, CA
  4. 1.8 7 km SSE of Sunol, CA
  5. 1.7 2 km NNE of San Ramon, CA
  6. 2.9 11 km ENE of Milpitas, CA
  7. 1.8 4 km ENE of San Leandro, CA
  8. 2.5 7 km SSE of Sunol, CA
  9. 1.8 7 km SSE of Sunol, CA
  10. 1.6 8 km NE of Alum Rock, CA
  11. 1.9 2 km WNW of Diablo, CA
  12. 1.6 17 km SSE of Livermore, CA
  13. 2.3 8 km NE of Alum Rock, CA
  14. 3.4 8 km NE of Alum Rock, CA
  15. 2.3 9 km ESE of Fremont, 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 5.1 on 2022-10-25 — it released about 27,000 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.