QuakeIndex

Earthquake · reviewed by a seismologist

M 3.5mw

2 km ENE of Pleasant Hill, CA

· 12 km deep · released about 3.1 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 9 kmSolano County 35 kmAlameda County 37 kmMarin County 63 kmNapa County 66 kmSan Mateo County 67 kmSan Joaquin County 68 kmYolo County 81 kmSacramento County 82 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 3.5 (mw)
Depth
12 km below the surface
Felt
5257 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
Nearest
Contra Costa County, 9 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 307 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 5257 people have reported feeling it to USGS.

How big was it?

This earthquake released about 3.1 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 55,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,500× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,700× the energy of this one
  4. This earthquake M 3.5 about 3.1 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 6.5× 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 37.9602, -122.0425. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 9 km (6 mi) WNW of here earthquakes near Contra Costa County
Solano County, CA 35 km (22 mi) SSW of here earthquakes near Solano County
Alameda County, CA 37 km (23 mi) NNW of here earthquakes near Alameda County
Marin County, CA 63 km (39 mi) E of here earthquakes near Marin County
Napa County, CA 66 km (41 mi) SSE of here earthquakes near Napa County
San Mateo County, CA 67 km (42 mi) NNE 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

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

  1. 1.7 4 km W of Alamo, CA
  2. 2.5 4 km W of Alamo, CA
  3. 2.5 4 km W of Alamo, CA
  4. 1.7 13 km NNE of Pittsburg, CA
  5. 1.6 1 km S of Pacheco, CA
  6. 1.7 0 km NNE of East Richmond Heights, CA
  7. 1.5 7 km E of Vallejo, CA
  8. 1.8 3 km ESE of Pacheco, CA
  9. 1.8 6 km SW of Clayton, CA
  10. 1.5 4 km SE of Oakland, CA
  11. 1.6 3 km SW of Clayton, CA
  12. 2.3 2 km E of Hayward, CA
  13. 1.6 6 km SW of Clayton, CA
  14. 1.8 2 km E of Hayward, CA
  15. 2.2 7 km NE of Alamo, 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 24 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.