QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

5km SW of Antioch, CA

· 19 km deep · released about 38 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 11 kmSolano County 33 kmAlameda County 37 kmSan Joaquin County 50 kmSacramento County 68 kmNapa County 72 kmSan Mateo County 78 kmYolo County 78 kmMarin County 79 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 2.1 (md)
Depth
19 km below the surface
Felt
1 report · strongest reported intensity I
Nearest
Contra Costa County, 11 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1271 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 38 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 390,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 280,000× the energy of this one
  3. Around the size people start to feel M 3.0 25× the energy of this one
  4. This earthquake M 2.1 about 38 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 37.9772, -121.8440. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 11 km (7 mi) NE of here earthquakes near Contra Costa County
Solano County, CA 33 km (21 mi) SSE of here earthquakes near Solano County
Alameda County, CA 37 km (23 mi) N of here earthquakes near Alameda County
San Joaquin County, CA 50 km (31 mi) W of here earthquakes near San Joaquin County
Sacramento County, CA 68 km (42 mi) SW of here earthquakes near Sacramento County
Napa County, CA 72 km (45 mi) SE of here earthquakes near Napa County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

  1. 1.7 2km N of San Leandro, CA
  2. 1.5 8km SSW of Livermore, CA
  3. 1.5 8km SSW of Brentwood, CA
  4. 2.0 2km NE of Danville, CA
  5. 1.9 2km W of Diablo, CA
  6. 1.9 2km NE of Danville, CA
  7. 1.7 9km NE of Blackhawk, CA
  8. 1.5 3km ESE of San Ramon, CA
  9. 2.7 3km NE of San Leandro, CA
  10. 1.5 3km E of Oakland, CA
  11. 2.0 3km NNE of Fremont, CA
  12. 1.5 2km NNE of Pleasant Hill, CA
  13. 1.7 7km SSW of Antioch, CA
  14. 2.1 4km S of Pittsburg, CA
  15. 1.8 9km SSW of Brentwood, 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 3,800 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.