QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

12km WSW of Portola Valley, CA

· 5.1 km deep · released about 10 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 10 kmSanta Cruz County 46 kmAlameda County 53 kmSanta Clara County 60 kmSan Francisco County 75 kmContra Costa County 75 kmMarin County 88 kmSolano County 111 kmSan Joaquin County 117 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 1.7 (md)
Depth
5.1 km below the surface
Felt
no reports yet
Nearest
San Mateo County, 10 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2491 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 10 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 92× the energy of this one
  4. This earthquake M 1.7 about 10 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 37.3260, -122.3522. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Mateo County, CA 10 km (6 mi) S of here earthquakes near San Mateo County
Santa Cruz County, CA 46 km (29 mi) NW of here earthquakes near Santa Cruz County
Alameda County, CA 53 km (33 mi) SW of here earthquakes near Alameda County
Santa Clara County, CA 60 km (37 mi) WNW of here earthquakes near Santa Clara County
San Francisco County, CA 75 km (46 mi) SE of here earthquakes near San Francisco County
Contra Costa County, CA 75 km (46 mi) SSW of here earthquakes near Contra Costa County

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

Aftershocks so far

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

  1. 1.9 6km E of Fremont, CA
  2. 3.0 22km W of Bonny Doon, CA
  3. 1.6 3km ESE of Union City, CA
  4. 1.8 9km NNE of Milpitas, CA
  5. 2.0 3km W of Portola Valley, CA
  6. 1.5 3km W of Portola Valley, CA
  7. 1.6 3km W of Portola Valley, CA
  8. 1.9 3km W of Portola Valley, CA
  9. 2.7 3km W of Portola Valley, CA
  10. 1.7 3km W of Portola Valley, CA
  11. 1.5 9km N of Boulder Creek, CA
  12. 1.7 3km W of Portola Valley, CA
  13. 1.8 3km W of Portola Valley, CA
  14. 1.8 2km SW of Los Altos Hills, CA
  15. 1.8 4km W of San Francisco Zoo, 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.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.