QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0md

1km NE of San Ramon, CA

· 9.4 km deep · released about 890 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 15 kmAlameda County 17 kmSolano County 53 kmSan Mateo County 55 kmSan Joaquin County 63 kmSanta Clara County 68 kmMarin County 74 kmNapa County 86 kmSanta Cruz County 86 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 3.0 (md)
Depth
9.4 km below the surface
Felt
259 reports · strongest reported intensity VI
Nearest
Contra Costa County, 15 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1709 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 259 people have reported feeling it to USGS.

How big was it?

This earthquake released about 890 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 380,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 17,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 12,000× the energy of this one
  4. This earthquake M 3.0 about 890 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 37.7893, -121.9675. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 15 km (9 mi) S of here earthquakes near Contra Costa County
Alameda County, CA 17 km (10 mi) NNW of here earthquakes near Alameda County
Solano County, CA 53 km (33 mi) S of here earthquakes near Solano County
San Mateo County, CA 55 km (34 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 68 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. 1.6 12km SW of Mountain House, CA
  2. 1.5 1km SE of Pacifica, CA
  3. 1.6 1km NE of Byron, CA
  4. 1.9 6km WNW of Dublin, CA
  5. 2.2 5km WNW of Dublin, CA
  6. 1.6 4km N of Lafayette, CA
  7. 1.6 5km N of Lafayette, CA
  8. 1.9 8km E of Fremont, CA
  9. 1.6 2km NNE of San Ramon, CA
  10. 2.4 6km N of Diablo, CA
  11. 2.1 11km SSW of Brentwood, CA
  12. 1.6 1km NE of San Ramon, CA
  13. 1.5 4km WSW of Colma, CA
  14. 1.7 5km WSW of Pacheco, CA
  15. 1.5 2km NE of Union City, 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 170 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.