QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9md

3 km SSW of San Francisco Zoo, CA

· 7.0 km deep · released about 650 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 35 kmMarin County 44 kmSan Francisco County 45 kmAlameda County 54 kmContra Costa County 55 kmSolano County 80 kmSanta Cruz County 89 kmSanta Clara County 91 kmNapa County 91 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 2.9 (md)
Depth
7.0 km below the surface
Felt
1085 reports · strongest reported intensity IV
Nearest
San Mateo County, 35 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 78 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 1085 people have reported feeling it to USGS.

How big was it?

This earthquake released about 650 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 23,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 16,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.5× the energy of this one
  4. This earthquake M 2.9 about 650 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 37.7042, -122.5162. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Mateo County, CA 35 km (22 mi) NNW of here earthquakes near San Mateo County
Marin County, CA 44 km (27 mi) SSE of here earthquakes near Marin County
San Francisco County, CA 45 km (28 mi) E of here earthquakes near San Francisco County
Alameda County, CA 54 km (33 mi) W of here earthquakes near Alameda County
Contra Costa County, CA 55 km (34 mi) WSW of here earthquakes near Contra Costa County
Solano County, CA 80 km (50 mi) SW of here earthquakes near Solano County

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

Aftershocks so far

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

  1. 2.1 3 km NNE of San Leandro, CA
  2. 1.9 0 km SSW of Pleasant Hill, CA
  3. 2.0 2 km SSW of Alamo, CA
  4. 1.8 2 km SW of Alamo, CA
  5. 1.5 7 km E of Santa Venetia, CA
  6. 1.9 2 km SE of Oakland, CA
  7. 1.6 2 km W of Portola Valley, CA
  8. 2.0 2 km ENE of Berkeley, CA
  9. 2.6 2 km NNE of San Leandro, CA
  10. 1.5 2 km ESE of Pacifica, CA
  11. 1.5 2 km SE of Pacifica, CA
  12. 1.5 3 km SE of Pacifica, CA
  13. 1.8 2 km SW of Alamo, CA
  14. 1.7 2 km SSE of Pacifica, CA
  15. 2.0 2 km ENE of Hayward, 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 230 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.