QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4mw

24km NE of Alum Rock, CA

· 7.6 km deep · released about 1.6 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alameda County 30 kmSanta Clara County 32 kmStanislaus County 55 kmContra Costa County 55 kmSan Joaquin County 57 kmSanta Cruz County 64 kmSan Mateo County 67 kmMerced County 86 kmSolano County 90 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 3.4 (mw)
Depth
7.6 km below the surface
Felt
73 reports · strongest reported intensity III
Nearest
Alameda County, 30 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1394 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 73 people have reported feeling it to USGS.

How big was it?

This earthquake released about 1.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 110,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,700× the energy of this one
  3. Magna, Utah 2020 M 5.7 3,300× the energy of this one
  4. This earthquake M 3.4 about 1.6 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 3.3× more

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 37.5000, -121.6207. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Alameda County, CA 30 km (19 mi) ESE of here earthquakes near Alameda County
Santa Clara County, CA 32 km (20 mi) N of here earthquakes near Santa Clara County
Stanislaus County, CA 55 km (34 mi) W of here earthquakes near Stanislaus County
Contra Costa County, CA 55 km (34 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) NNE 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

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

  1. 1.9 4km ENE of San Ramon, CA
  2. 2.1 16km N of Morgan Hill, CA
  3. 1.6 6km ESE of Pleasanton, CA
  4. 1.6 15km N of Morgan Hill, CA
  5. 1.8 7km SE of Pleasanton, CA
  6. 2.8 9km NE of Alum Rock, CA
  7. 2.8 15km E of Seven Trees, CA
  8. 2.0 7km ESE of Pleasanton, CA
  9. 1.7 7km SE of Pleasanton, CA
  10. 1.7 9km NE of Gilroy, CA
  11. 2.8 14km ESE of Alum Rock, CA
  12. 1.5 6km SE of Pleasanton, CA
  13. 1.8 6km SE of Pleasanton, CA
  14. 2.8 6km SE of Pleasanton, CA
  15. 2.4 6km ESE of Pleasanton, 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 28 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.