QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8md

2km N of Piedmont, CA

· 5.5 km deep · released about 420 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 26 kmAlameda County 36 kmSan Mateo County 49 kmMarin County 50 kmSolano County 54 kmSan Francisco County 71 kmNapa County 74 kmSanta Clara County 84 kmSan Joaquin County 85 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 2.8 (md)
Depth
5.5 km below the surface
Felt
2614 reports · strongest reported intensity V
Nearest
Contra Costa County, 26 km ENE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1433 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 2614 people have reported feeling it to USGS.

How big was it?

This earthquake released about 420 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 36,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 26,000× the energy of this one
  3. Around the size people start to feel M 3.0 2.3× the energy of this one
  4. This earthquake M 2.8 about 420 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 37.8457, -122.2350. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 26 km (16 mi) WSW of here earthquakes near Contra Costa County
Alameda County, CA 36 km (22 mi) NW of here earthquakes near Alameda County
San Mateo County, CA 49 km (31 mi) NNE of here earthquakes near San Mateo County
Marin County, CA 50 km (31 mi) ESE of here earthquakes near Marin County
Solano County, CA 54 km (33 mi) SSW of here earthquakes near Solano County
San Francisco County, CA 71 km (44 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

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

  1. 1.5 2km ESE of Berkeley, CA
  2. 1.5 4km E of Moraga, CA
  3. 1.8 7km S of Muir Beach, CA
  4. 2.2 4km NNE of Blackhawk, CA
  5. 2.5 4km NNE of Blackhawk, CA
  6. 2.0 4km NE of Blackhawk, CA
  7. 1.9 4km SSW of Colma, CA
  8. 2.3 2km WNW of Concord, CA
  9. 1.7 2km E of Berkeley, CA
  10. 1.8 5km E of Fremont, CA
  11. 2.1 8km S of Muir Beach, CA
  12. 1.6 8km S of Muir Beach, CA
  13. 1.6 3km NNW of Piedmont, CA
  14. 2.1 2km ENE of Berkeley, CA
  15. 1.7 3km WNW of Castro Valley, 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 350 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.