QuakeIndex

Earthquake · automatic estimate, may change

M 2.9md

2 km E of Piedmont, CA

· 4.6 km deep · released about 590 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 25 kmAlameda County 33 kmSan Mateo County 48 kmMarin County 53 kmSolano County 55 kmSan Francisco County 73 kmNapa County 77 kmSanta Clara County 81 kmSan Joaquin County 83 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 2.9 (md)
Depth
4.6 km below the surface
Felt
2458 reports · strongest reported intensity IV
Nearest
Contra Costa County, 25 km ENE
Status
Automatic — a machine’s first estimate, which may change

USGS · last changed by USGS · we first saw it 207 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 2458 people have reported feeling it to USGS.

How big was it?

This earthquake released about 590 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 26,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 18,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.6× the energy of this one
  4. This earthquake M 2.9 about 590 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 37.8232, -122.2122. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 25 km (16 mi) WSW of here earthquakes near Contra Costa County
Alameda County, CA 33 km (20 mi) NW of here earthquakes near Alameda County
San Mateo County, CA 48 km (30 mi) NNE of here earthquakes near San Mateo County
Marin County, CA 53 km (33 mi) ESE of here earthquakes near Marin County
Solano County, CA 55 km (34 mi) SSW of here earthquakes near Solano County
San Francisco County, CA 73 km (45 mi) E of here earthquakes near San Francisco County

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

Aftershocks so far

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

  1. 2.6 4 km SE of San Ramon, CA
  2. 1.5 4 km SE of San Ramon, CA
  3. 1.6 4 km N of Dublin, CA
  4. 1.8 4 km SE of San Ramon, CA
  5. 2.1 5 km SE of San Ramon, CA
  6. 1.9 5 km N of Dublin, CA
  7. 2.0 5 km SE of San Ramon, CA
  8. 1.7 5 km SE of San Ramon, CA
  9. 2.2 5 km SE of San Ramon, CA
  10. 2.0 5 km SE of San Ramon, CA
  11. 2.2 5 km SE of San Ramon, CA
  12. 1.6 4 km SE of San Ramon, CA
  13. 2.9 4 km SE of San Ramon, CA
  14. 2.0 5 km SE of San Ramon, CA
  15. 1.5 5 km N of Dublin, 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 250 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.