QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

13km NNW of Boulder Creek, CA

· 13 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 26 kmSanta Cruz County 29 kmSanta Clara County 44 kmAlameda County 52 kmContra Costa County 79 kmSan Francisco County 93 kmMarin County 104 kmStanislaus County 111 kmSan Joaquin County 112 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
13 km below the surface
Felt
no reports yet
Nearest
San Mateo County, 26 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2593 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 37.2310, -122.1827. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Mateo County, CA 26 km (16 mi) SE of here earthquakes near San Mateo County
Santa Cruz County, CA 29 km (18 mi) NNW of here earthquakes near Santa Cruz County
Santa Clara County, CA 44 km (27 mi) W of here earthquakes near Santa Clara County
Alameda County, CA 52 km (32 mi) SSW of here earthquakes near Alameda County
Contra Costa County, CA 79 km (49 mi) SSW of here earthquakes near Contra Costa County
San Francisco County, CA 93 km (58 mi) SE 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

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

  1. 1.7 6km SSE of Portola Valley, CA
  2. 1.7 9km NNE of Alum Rock, CA
  3. 2.9 5km NE of Alum Rock, CA
  4. 1.6 3km WSW of Portola Valley, CA
  5. 2.0 3km WSW of Portola Valley, CA
  6. 1.5 15km E of Seven Trees, CA
  7. 1.8 8km NE of Alum Rock, CA
  8. 2.3 16km N of Morgan Hill, CA
  9. 1.6 9km NE of Alum Rock, CA
  10. 2.2 15km N of Morgan Hill, CA
  11. 1.5 3km NE of Union City, CA
  12. 2.6 12km W of Saratoga, CA
  13. 1.6 3km ESE of Hayward, CA
  14. 2.0 6km S of Loyola, CA
  15. 1.8 2km SE of Pacifica, 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 7,200 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.