QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3md

3km ENE of San Ramon, CA

· 11 km deep · released about 91 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 14 kmAlameda County 16 kmSolano County 53 kmSan Mateo County 56 kmSan Joaquin County 61 kmSanta Clara County 67 kmMarin County 76 kmNapa County 86 kmSanta Cruz County 87 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 2.3 (md)
Depth
11 km below the surface
Felt
5 reports · strongest reported intensity II
Nearest
Contra Costa County, 14 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2166 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 5 people have reported feeling it to USGS.

How big was it?

This earthquake released about 91 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 170,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 120,000× the energy of this one
  3. Around the size people start to feel M 3.0 10× the energy of this one
  4. This earthquake M 2.3 about 91 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 37.7897, -121.9482. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 14 km (9 mi) S of here earthquakes near Contra Costa County
Alameda County, CA 16 km (10 mi) N of here earthquakes near Alameda County
Solano County, CA 53 km (33 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 61 km (38 mi) WSW of here earthquakes near San Joaquin County
Santa Clara County, CA 67 km (42 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

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

  1. 2.1 2km WNW of Concord, CA
  2. 3.6 2km W of Concord, CA
  3. 2.0 2km NNW of Kensington, CA
  4. 1.6 3km ESE of Union City, CA
  5. 2.3 4km ENE of Walnut Creek, CA
  6. 3.0 8km NE of Alum Rock, CA
  7. 1.9 2km SE of Pacheco, CA
  8. 2.6 3km WNW of Concord, CA
  9. 1.8 9km ENE of Milpitas, CA
  10. 1.5 3km NNE of Vine Hill, CA
  11. 1.8 10km ESE of Livermore, CA
  12. 2.1 9km ENE of Milpitas, CA
  13. 2.6 0km E of San Pablo, CA
  14. 2.0 14km SE of Livermore, CA
  15. 2.6 1km WNW of Bay Point, 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 1,600 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.