QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

6km SW of Clayton, CA

· 10 km deep · released about 25 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 3 kmAlameda County 30 kmSolano County 40 kmSan Joaquin County 63 kmSan Mateo County 65 kmMarin County 69 kmNapa County 73 kmSanta Clara County 81 kmSacramento County 82 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
10 km below the surface
Felt
1 report · strongest reported intensity I
Nearest
Contra Costa County, 3 km ENE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1619 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 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 37.9088, -121.9843. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 3 km (2 mi) WSW of here earthquakes near Contra Costa County
Alameda County, CA 30 km (19 mi) NNW of here earthquakes near Alameda County
Solano County, CA 40 km (25 mi) S of here earthquakes near Solano County
San Joaquin County, CA 63 km (39 mi) W of here earthquakes near San Joaquin County
San Mateo County, CA 65 km (40 mi) NNE of here earthquakes near San Mateo County
Marin County, CA 69 km (43 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

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

  1. 1.8 3km NW of Orinda, CA
  2. 1.6 5km ENE of Walnut Creek, CA
  3. 2.2 9km NE of Milpitas, CA
  4. 1.8 3km NNE of San Leandro, CA
  5. 1.7 11km SE of Livermore, CA
  6. 1.8 12km SE of Livermore, CA
  7. 1.9 4km W of Pleasant Hill, CA
  8. 1.8 11km NE of Milpitas, CA
  9. 1.8 2km E of Walnut Creek, CA
  10. 1.5 4km WNW of Orinda, CA
  11. 1.6 6km WNW of Dublin, CA
  12. 1.9 3km SW of American Canyon, CA
  13. 2.5 4km SSE of Rodeo, CA
  14. 1.8 2km SSE of Alamo, CA
  15. 1.9 9km NE of Milpitas, 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.