QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

2km ESE of Alamo, CA

· 16 km deep · released about 15 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 10 kmAlameda County 24 kmSolano County 47 kmSan Mateo County 57 kmSan Joaquin County 66 kmMarin County 68 kmSanta Clara County 75 kmNapa County 78 kmSacramento County 89 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 1.8 (md)
Depth
16 km below the surface
Felt
no reports yet
Nearest
Contra Costa County, 10 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2505 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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 37.8455, -122.0167. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 10 km (6 mi) SW of here earthquakes near Contra Costa County
Alameda County, CA 24 km (15 mi) NNW of here earthquakes near Alameda County
Solano County, CA 47 km (29 mi) S of here earthquakes near Solano County
San Mateo County, CA 57 km (36 mi) NNE of here earthquakes near San Mateo County
San Joaquin County, CA 66 km (41 mi) W of here earthquakes near San Joaquin County
Marin County, CA 68 km (42 mi) ESE of here earthquakes near Marin County

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

Aftershocks so far

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

  1. 1.9 2km SE of Pacheco, CA
  2. 1.7 5km NW of Sunol, CA
  3. 2.1 2km NW of Concord, CA
  4. 1.8 1km ESE of Pacheco, CA
  5. 1.9 2km NNE of San Ramon, CA
  6. 2.2 1km SW of Danville, CA
  7. 1.9 4km N of Diablo, CA
  8. 1.5 6km ENE of Vallejo, CA
  9. 1.6 11km ESE of Sunol, CA
  10. 2.4 11km ESE of Sunol, CA
  11. 1.5 10km E of Blackhawk, CA
  12. 1.5 3km NE of Union City, CA
  13. 1.9 3km NW of Castro Valley, CA
  14. 1.5 5km E of Oakland, CA
  15. 1.5 5km E of Vallejo, 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 9,800 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.