QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

5km SW of Pacheco, CA

· 9.7 km deep · released about 18 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 15 kmSolano County 38 kmAlameda County 39 kmMarin County 56 kmNapa County 64 kmSan Mateo County 64 kmSan Joaquin County 74 kmYolo County 83 kmSan Francisco County 84 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
9.7 km below the surface
Felt
1 report · strongest reported intensity IV
Nearest
Contra Costa County, 15 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1815 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 18 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 5.8 840,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 600,000× the energy of this one
  3. Around the size people start to feel M 3.0 53× the energy of this one
  4. This earthquake M 1.9 about 18 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 37.9568, -122.1207. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 15 km (10 mi) WNW of here earthquakes near Contra Costa County
Solano County, CA 38 km (24 mi) SSW of here earthquakes near Solano County
Alameda County, CA 39 km (24 mi) NNW of here earthquakes near Alameda County
Marin County, CA 56 km (35 mi) E of here earthquakes near Marin County
Napa County, CA 64 km (40 mi) SSE of here earthquakes near Napa County
San Mateo County, CA 64 km (40 mi) NNE of here earthquakes near San Mateo County

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

Aftershocks so far

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

  1. 1.6 3km SE of Concord, CA
  2. 2.2 2km E of Pacheco, CA
  3. 1.6 6km WSW of Colma, CA
  4. 2.5 4km N of San Leandro, CA
  5. 1.8 1km NE of San Ramon, CA
  6. 2.0 1km W of Kensington, CA
  7. 2.5 1km W of Kensington, CA
  8. 1.7 5km ENE of Vallejo, CA
  9. 1.9 7km ESE of Bethel Island, CA
  10. 1.9 8km SSW of Brentwood, CA
  11. 1.7 5km E of Fremont, CA
  12. 1.7 8km WSW of Mountain House, CA
  13. 1.6 8km E of Vallejo, CA
  14. 1.9 1km NE of San Ramon, CA
  15. 1.7 1km NE of San Ramon, 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 8,200 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.