QuakeIndex

Earthquake · reviewed by a seismologist

M 3.3mw

8 km E of Clayton, CA

· 7.5 km deep · released about 1.2 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 9 kmAlameda County 33 kmSolano County 37 kmSan Joaquin County 51 kmSacramento County 72 kmSan Mateo County 74 kmNapa County 75 kmMarin County 79 kmSanta Clara County 81 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 3.3 (mw)
Depth
7.5 km below the surface
Felt
642 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
Nearest
Contra Costa County, 9 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 298 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 642 people have reported feeling it to USGS.

How big was it?

This earthquake released about 1.2 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 6.7 140,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 6,200× the energy of this one
  3. Magna, Utah 2020 M 5.7 4,400× the energy of this one
  4. This earthquake M 3.3 about 1.2 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2.5× 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 37.9412, -121.8502. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 9 km (6 mi) ENE of here earthquakes near Contra Costa County
Alameda County, CA 33 km (21 mi) N of here earthquakes near Alameda County
Solano County, CA 37 km (23 mi) SSE of here earthquakes near Solano County
San Joaquin County, CA 51 km (31 mi) W of here earthquakes near San Joaquin County
Sacramento County, CA 72 km (45 mi) SW of here earthquakes near Sacramento County
San Mateo County, CA 74 km (46 mi) NE of here earthquakes near San Mateo County

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

Aftershocks so far

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

  1. 2.3 3 km SE of San Ramon, CA
  2. 3.0 4 km SE of San Ramon, CA
  3. 2.9 4 km SE of San Ramon, CA
  4. 2.3 4 km SE of San Ramon, CA
  5. 3.0 4 km SE of San Ramon, CA
  6. 3.8 3 km SE of San Ramon, CA
  7. 1.7 6 km ENE of Vallejo, CA
  8. 1.6 5 km SE of Oakland, CA
  9. 1.7 4 km E of Brentwood, CA
  10. 2.4 5 km SE of Oakland, CA
  11. 2.6 2 km WNW of Concord, CA
  12. 1.6 8 km NNW of Lafayette, CA
  13. 2.0 8 km E of Suisun City, CA
  14. 2.0 2 km ENE of San Ramon, CA
  15. 1.6 7 km NNW of Lafayette, 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 4.5 on 2019-10-15 — it released about 61 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.