QuakeIndex

Earthquake · reviewed by a seismologist

M 5.1mw

15km ESE of Alum Rock, CA

· 8.4 km deep · released about 590 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Clara County 10 kmAlameda County 43 kmSanta Cruz County 45 kmSan Mateo County 63 kmStanislaus County 65 kmContra Costa County 72 kmSan Joaquin County 78 kmMerced County 85 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 5.1 (mw)
Depth
8.4 km below the surface
Felt
24205 reports · strongest reported intensity V
Measured shaking
intensity V (ShakeMap)
USGS impact alert
green
Nearest
Santa Clara County, 10 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 166 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 24205 people have reported feeling it to USGS.

How big was it?

This earthquake released about 590 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 290× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 13× the energy of this one
  3. Magna, Utah 2020 M 5.7 9.1× the energy of this one
  4. This earthquake M 5.1 about 590 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 1,200× 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 37.3115, -121.6720. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Santa Clara County, CA 10 km (6 mi) N of here earthquakes near Santa Clara County
Alameda County, CA 43 km (27 mi) SSE of here earthquakes near Alameda County
Santa Cruz County, CA 45 km (28 mi) NE of here earthquakes near Santa Cruz County
San Mateo County, CA 63 km (39 mi) E of here earthquakes near San Mateo County
Stanislaus County, CA 65 km (41 mi) WSW of here earthquakes near Stanislaus County
Contra Costa County, CA 72 km (45 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

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

  1. 2.0 15km E of Seven Trees, CA
  2. 1.6 18km WSW of Westley, CA
  3. 1.8 2km E of Aromas, CA
  4. 1.6 15km N of Morgan Hill, CA
  5. 1.5 10km E of Gilroy, CA
  6. 1.6 5km WSW of Cupertino, CA
  7. 2.6 4km ESE of Aromas, CA
  8. 1.6 16km E of Seven Trees, CA
  9. 2.1 12km ESE of Alum Rock, CA
  10. 3.6 13km ESE of Alum Rock, CA
  11. 1.8 6km SSW of Gilroy, CA
  12. 1.8 3km WSW of Cupertino, CA
  13. 1.7 2km ENE of Aromas, CA
  14. 2.0 16km E of Seven Trees, CA
  15. 2.9 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 4.2 on 2021-01-17.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.