QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

2km NNE of San Ramon, CA

· 8.2 km deep · released about 25 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 14 kmAlameda County 17 kmSolano County 52 kmSan Mateo County 55 kmSan Joaquin County 63 kmSanta Clara County 68 kmMarin County 74 kmNapa County 85 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 1.9 (md)
Depth
8.2 km below the surface
Felt
2 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 2393 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 2 people have reported feeling it to USGS.

How big was it?

This earthquake released about 25 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 620,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 440,000× the energy of this one
  3. Around the size people start to feel M 3.0 39× the energy of this one
  4. This earthquake M 1.9 about 25 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 37.7965, -121.9673. 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 17 km (11 mi) NNW of here earthquakes near Alameda County
Solano County, CA 52 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 (43 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

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

  1. 1.8 11km NNW of Pittsburg, CA
  2. 1.9 2km NE of Danville, CA
  3. 1.6 4km ESE of Fremont, CA
  4. 1.8 13km SSE of Livermore, CA
  5. 1.5 8km WSW of Mountain House, CA
  6. 2.1 8km WSW of Mountain House, CA
  7. 1.9 8km SW of Brentwood, CA
  8. 2.0 9km WSW of Mountain House, CA
  9. 2.0 7km SE of Blackhawk, CA
  10. 1.8 8km ESE of Blackhawk, CA
  11. 1.7 10km SW of Brentwood, CA
  12. 1.7 9km WSW of Mountain House, CA
  13. 1.7 4km NW of Orinda, CA
  14. 1.5 4km NNE of Fairview, CA
  15. 1.5 2km E of Berkeley, 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 6,000 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.