QuakeIndex

Earthquake · reviewed by a seismologist

M 2.0md

11km SSE of Portola Valley, CA

· 4.3 km deep · released about 35 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 21 kmSanta Cruz County 35 kmSanta Clara County 46 kmAlameda County 48 kmContra Costa County 74 kmSan Francisco County 88 kmMarin County 98 kmSan Joaquin County 109 kmStanislaus County 110 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 2.0 (md)
Depth
4.3 km below the surface
Felt
no reports yet
Nearest
San Mateo County, 21 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2837 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 35 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 440,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 310,000× the energy of this one
  3. Around the size people start to feel M 3.0 28× the energy of this one
  4. This earthquake M 2.0 about 35 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 37.2858, -122.2013. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Mateo County, CA 21 km (13 mi) SE of here earthquakes near San Mateo County
Santa Cruz County, CA 35 km (22 mi) NNW of here earthquakes near Santa Cruz County
Santa Clara County, CA 46 km (28 mi) W of here earthquakes near Santa Clara County
Alameda County, CA 48 km (30 mi) SSW of here earthquakes near Alameda County
Contra Costa County, CA 74 km (46 mi) SSW of here earthquakes near Contra Costa County
San Francisco County, CA 88 km (55 mi) ESE of here earthquakes near San Francisco County

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

Aftershocks so far

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

  1. 2.8 21km WNW of Boulder Creek, CA
  2. 1.9 20km WNW of Boulder Creek, CA
  3. 2.2 5km WSW of Cupertino, CA
  4. 1.8 10km E of Alum Rock, CA
  5. 2.9 3km NNE of Corralitos, CA
  6. 2.1 9km NNE of Alum Rock, CA
  7. 1.9 3km S of Loyola, CA
  8. 1.5 9km NNE of Alum Rock, CA
  9. 1.6 8km SE of Seven Trees, CA
  10. 2.0 3km E of Union City, CA
  11. 1.7 5km WNW of Sunol, CA
  12. 1.5 3km S of Loyola, CA
  13. 2.3 8km E of Alum Rock, CA
  14. 1.8 8km SSE of Portola Valley, CA
  15. 2.1 3km SW of Monte Sereno, 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 4.1 on 2017-10-10 — it released about 1,200 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.