QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

9km ENE of Milpitas, CA

· 6.3 km deep · released about 51 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alameda County 23 kmSanta Clara County 28 kmSan Mateo County 50 kmSanta Cruz County 52 kmContra Costa County 53 kmSan Joaquin County 71 kmStanislaus County 72 kmSolano County 91 kmMerced County 100 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
6.3 km below the surface
Felt
2 reports · strongest reported intensity II
Nearest
Alameda County, 23 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2088 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 51 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 5.8 300,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 210,000× 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 51 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 37.4543, -121.8075. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Alameda County, CA 23 km (15 mi) SSE of here earthquakes near Alameda County
Santa Clara County, CA 28 km (17 mi) NNW of here earthquakes near Santa Clara County
San Mateo County, CA 50 km (31 mi) E of here earthquakes near San Mateo County
Santa Cruz County, CA 52 km (32 mi) NNE of here earthquakes near Santa Cruz County
Contra Costa County, CA 53 km (33 mi) SSE of here earthquakes near Contra Costa 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

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

  1. 1.5 9km ENE of Milpitas, CA
  2. 2.0 9km ENE of Milpitas, CA
  3. 2.3 14km SE of Livermore, CA
  4. 2.9 14km SE of Livermore, CA
  5. 2.4 20km SE of Livermore, CA
  6. 1.6 10km NE of Milpitas, CA
  7. 2.1 4km WSW of Pleasanton, CA
  8. 1.9 9km NNE of Alum Rock, CA
  9. 2.6 7km E of Alum Rock, CA
  10. 2.5 15km ENE of Alum Rock, CA
  11. 1.7 10km SE of Sunol, CA
  12. 2.5 15km N of Morgan Hill, CA
  13. 1.6 16km N of Morgan Hill, CA
  14. 2.1 10km SE of Sunol, CA
  15. 2.0 15km E of Seven Trees, 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 4.3 on 2019-07-16 — it released about 1,700 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.