QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8md

2km ESE of Danville, CA

· 7.2 km deep · released about 460 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 12 kmAlameda County 20 kmSolano County 50 kmSan Mateo County 56 kmSan Joaquin County 63 kmSanta Clara County 71 kmMarin County 72 kmNapa County 82 kmSanta Cruz County 90 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
7.2 km below the surface
Felt
121 reports · strongest reported intensity IV
Nearest
Contra Costa County, 12 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3021 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 121 people have reported feeling it to USGS.

How big was it?

This earthquake released about 460 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 33,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 23,000× the energy of this one
  3. Around the size people start to feel M 3.0 2.1× the energy of this one
  4. This earthquake M 2.8 about 460 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 37.8170, -121.9798. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 12 km (7 mi) SSW of here earthquakes near Contra Costa County
Alameda County, CA 20 km (12 mi) NNW of here earthquakes near Alameda County
Solano County, CA 50 km (31 mi) S of here earthquakes near Solano County
San Mateo County, CA 56 km (35 mi) NE of here earthquakes near San Mateo County
San Joaquin County, CA 63 km (39 mi) WSW of here earthquakes near San Joaquin County
Santa Clara County, CA 71 km (44 mi) NNW of here earthquakes near Santa Clara 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. 1.8 9km NNE of Alum Rock, CA
  2. 1.9 10km ESE of Sunol, CA
  3. 1.6 11km NE of Milpitas, CA
  4. 2.1 2km NE of Oakland, CA
  5. 2.8 2km NE of Oakland, CA
  6. 2.8 9km ENE of Milpitas, CA
  7. 2.0 1km S of Pleasant Hill, CA
  8. 1.5 2km WSW of San Lorenzo, CA
  9. 3.4 9km ENE of Milpitas, CA
  10. 3.3 2km NNW of Crockett, CA
  11. 2.1 5km E of Union City, CA
  12. 1.6 8km NE of Alum Rock, CA
  13. 1.5 3km NNW of Orinda, CA
  14. 2.5 9km N of Bay Point, CA
  15. 1.8 2km E 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 4.4 on 2018-01-04 — it released about 240 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.