QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

24 km ENE of Alum Rock, CA

· 4.8 km deep · released about 25 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Clara County 31 kmAlameda County 33 kmStanislaus County 53 kmContra Costa County 57 kmSan Joaquin County 57 kmSanta Cruz County 64 kmSan Mateo County 69 kmMerced County 84 kmSolano County 92 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 1.9 (md)
Depth
4.8 km below the surface
Felt
no reports yet
Nearest
Santa Clara County, 31 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1068 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 25 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 620,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 440,000× the energy of this one
  3. Around the size people start to feel M 3.0 39× the energy of this one
  4. This earthquake M 1.9 about 25 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 37.4870, -121.5983. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Santa Clara County, CA 31 km (19 mi) NNE of here earthquakes near Santa Clara County
Alameda County, CA 33 km (20 mi) ESE of here earthquakes near Alameda County
Stanislaus County, CA 53 km (33 mi) W of here earthquakes near Stanislaus County
Contra Costa County, CA 57 km (36 mi) SSE of here earthquakes near Contra Costa County
San Joaquin County, CA 57 km (36 mi) SSW of here earthquakes near San Joaquin County
Santa Cruz County, CA 64 km (40 mi) NE of here earthquakes near Santa Cruz County

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

Aftershocks so far

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

  1. 1.6 2 km N of Byron, CA
  2. 2.3 3 km NNE of Byron, CA
  3. 3.5 2 km NNE of Byron, CA
  4. 1.6 2 km N of Byron, CA
  5. 1.6 0 km NE of Byron, CA
  6. 1.9 9 km ENE of San Martin, CA
  7. 1.5 9 km NE of Alum Rock, CA
  8. 3.2 7 km E of Fremont, CA
  9. 1.6 2 km E of Hayward, CA
  10. 1.5 11 km WSW of Patterson, CA
  11. 2.7 15 km SW of Westley, CA
  12. 1.6 15 km N of Morgan Hill, CA
  13. 1.7 20 km WSW of Patterson, CA
  14. 1.7 9 km ENE of Morgan Hill, CA
  15. 2.1 1 km SSE of Los Altos Hills, 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 48,000 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.