QuakeIndex

Earthquake · reviewed by a seismologist

M 4.5mw

15 km SW of Westley, CA

· 3.5 km deep · released about 94 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Stanislaus County 29 kmSanta Clara County 42 kmSan Joaquin County 55 kmMerced County 57 kmAlameda County 59 kmContra Costa County 79 kmSanta Cruz County 79 kmSan Benito County 94 kmSan Mateo County 95 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 4.5 (mw)
Depth
3.5 km below the surface
Felt
3004 reports · strongest reported intensity V
Measured shaking
intensity V (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Stanislaus County, 29 km ENE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 728 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 3004 people have reported feeling it to USGS.

How big was it?

This earthquake released about 94 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 1,800× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 80× the energy of this one
  3. Magna, Utah 2020 M 5.7 57× the energy of this one
  4. This earthquake M 4.5 about 94 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 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 37.4382, -121.2958. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Stanislaus County, CA 29 km (18 mi) WSW of here earthquakes near Stanislaus County
Santa Clara County, CA 42 km (26 mi) NE of here earthquakes near Santa Clara County
San Joaquin County, CA 55 km (34 mi) S of here earthquakes near San Joaquin County
Merced County, CA 57 km (36 mi) WNW of here earthquakes near Merced County
Alameda County, CA 59 km (37 mi) ESE of here earthquakes near Alameda County
Contra Costa County, CA 79 km (49 mi) SE 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. 2.6 16 km E of Seven Trees, CA
  2. 1.7 9 km NNE of Alum Rock, CA
  3. 2.0 24 km SSW of Gustine, CA
  4. 2.1 10 km SE of Sunol, CA
  5. 1.5 8 km SSW of Livermore, CA
  6. 1.5 6 km NNE of Alum Rock, CA
  7. 2.0 14 km ESE of Alum Rock, CA
  8. 2.5 25 km SSW of Gustine, CA
  9. 2.1 11 km ESE of Alum Rock, CA
  10. 2.8 11 km ESE of Alum Rock, CA
  11. 1.6 24 km SSW of Gustine, CA
  12. 1.7 24 km SSW of Gustine, CA
  13. 2.6 8 km ENE of Alum Rock, CA
  14. 2.6 24 km SSW of Gustine, CA
  15. 1.9 24 km ENE of Alum Rock, 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 6.2 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.