QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

10 km SSW of Half Moon Bay, CA

· 11 km deep · released about 5.7 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 10 kmAlameda County 58 kmSanta Cruz County 59 kmSan Francisco County 62 kmSanta Clara County 72 kmContra Costa County 76 kmMarin County 78 kmSolano County 109 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 1.5 (md)
Depth
11 km below the surface
Felt
no reports yet
Nearest
San Mateo County, 10 km ENE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1125 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 5.7 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,900,000× the energy of this one
  3. Around the size people start to feel M 3.0 170× the energy of this one
  4. This earthquake M 1.5 about 5.7 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 37.3817, -122.4825. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Mateo County, CA 10 km (7 mi) WSW of here earthquakes near San Mateo County
Alameda County, CA 58 km (36 mi) WSW of here earthquakes near Alameda County
Santa Cruz County, CA 59 km (37 mi) NW of here earthquakes near Santa Cruz County
San Francisco County, CA 62 km (38 mi) SE of here earthquakes near San Francisco County
Santa Clara County, CA 72 km (45 mi) WNW of here earthquakes near Santa Clara County
Contra Costa County, CA 76 km (47 mi) SW 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

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

  1. 2.1 5 km SSE of Portola Valley, CA
  2. 2.1 6 km WNW of San Francisco Zoo, CA
  3. 1.7 5 km WSW of Colma, CA
  4. 1.5 4 km NNE of Lompico, CA
  5. 2.1 1 km SSE of Los Altos Hills, CA
  6. 2.5 2 km SSE of Los Altos Hills, CA
  7. 1.6 4 km WSW of Colma, CA
  8. 1.5 1 km N of Millbrae, CA
  9. 1.9 2 km NNE of Millbrae, CA
  10. 2.2 4 km WSW of Cupertino, CA
  11. 2.2 6 km WNW of San Francisco Zoo, CA
  12. 1.5 6 km WNW of San Francisco Zoo, CA
  13. 2.1 3 km N of San Lorenzo, CA
  14. 1.5 2 km ESE of Pacifica, CA
  15. 1.7 2 km NNE of Saratoga, 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.