QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8md

14km ESE of Alum Rock, CA

· 7.3 km deep · released about 530 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Clara County 11 kmAlameda County 42 kmSanta Cruz County 44 kmSan Mateo County 62 kmStanislaus County 66 kmContra Costa County 71 kmSan Joaquin County 78 kmMerced County 86 kmSan Benito County 94 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 2.8 (md)
Depth
7.3 km below the surface
Felt
137 reports · strongest reported intensity III
Nearest
Santa Clara County, 11 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1354 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 137 people have reported feeling it to USGS.

How big was it?

This earthquake released about 530 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 29,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 20,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.8× the energy of this one
  4. This earthquake M 2.8 about 530 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 37.3158, -121.6805. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Santa Clara County, CA 11 km (7 mi) N of here earthquakes near Santa Clara County
Alameda County, CA 42 km (26 mi) SSE of here earthquakes near Alameda County
Santa Cruz County, CA 44 km (28 mi) NE of here earthquakes near Santa Cruz County
San Mateo County, CA 62 km (39 mi) E of here earthquakes near San Mateo County
Stanislaus County, CA 66 km (41 mi) WSW of here earthquakes near Stanislaus County
Contra Costa County, CA 71 km (44 mi) SSE of here earthquakes near Contra Costa County

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

Aftershocks so far

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

  1. 1.8 2km SE of Portola Valley, CA
  2. 2.9 1km SE of Portola Valley, CA
  3. 1.7 2km SE of Portola Valley, CA
  4. 2.1 1km SE of Portola Valley, CA
  5. 2.0 8km W of Saratoga, CA
  6. 1.9 9km NE of Gilroy, CA
  7. 1.8 4km SSW of Cupertino, CA
  8. 2.1 12km NNE of Morgan Hill, CA
  9. 2.3 15km N of Morgan Hill, CA
  10. 2.1 9km NE of San Martin, CA
  11. 2.2 15km N of Morgan Hill, CA
  12. 2.5 8km NNE of Alum Rock, CA
  13. 1.7 10km E of Alum Rock, CA
  14. 2.4 9km ENE of San Martin, CA
  15. 2.0 3km NNE 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 2,200 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.