QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

1km NE of San Ramon, CA

· 9.3 km deep · released about 13 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 15 kmAlameda County 16 kmSolano County 54 kmSan Mateo County 54 kmSan Joaquin County 64 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 1.8 (md)
Depth
9.3 km below the surface
Felt
1 report · strongest reported intensity I
Nearest
Contra Costa County, 15 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1751 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 13 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 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 810,000× the energy of this one
  3. Around the size people start to feel M 3.0 72× the energy of this one
  4. This earthquake M 1.8 about 13 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 37.7863, -121.9712. 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 16 km (10 mi) NNW of here earthquakes near Alameda County
Solano County, CA 54 km (33 mi) S of here earthquakes near Solano County
San Mateo County, CA 54 km (34 mi) NE of here earthquakes near San Mateo County
San Joaquin County, CA 64 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

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

  1. 1.6 8km NNE of Milpitas, CA
  2. 1.8 19km SSE of Livermore, CA
  3. 2.0 1km NW of Concord, CA
  4. 1.6 2km NNE of Danville, CA
  5. 2.3 5km E of Blackhawk, CA
  6. 1.6 4km E of South San Francisco, CA
  7. 1.9 3km ESE of Pacheco, CA
  8. 1.9 8km E of Alum Rock, CA
  9. 1.7 2km SSW of Blackhawk, CA
  10. 1.5 5km WSW of Daly City, CA
  11. 1.6 2km NE of Union City, CA
  12. 1.8 3km ENE of San Leandro, CA
  13. 2.9 3km ENE of San Leandro, CA
  14. 1.6 2km ENE of Pacifica, CA
  15. 3.2 2km NNE of San Leandro, 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 11,000 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.