QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

9km N of Boulder Creek, CA

· 11 km deep · released about 5.6 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Cruz County 24 kmSan Mateo County 32 kmSanta Clara County 39 kmAlameda County 52 kmContra Costa County 81 kmSan Francisco County 99 kmStanislaus County 107 kmMarin County 109 kmSan Joaquin 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 1.5 (md)
Depth
11 km below the surface
Felt
no reports yet
Nearest
Santa Cruz County, 24 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2285 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 5.6 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 2,700,000× 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 5.6 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 37.2068, -122.1242. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Santa Cruz County, CA 24 km (15 mi) NNW of here earthquakes near Santa Cruz County
San Mateo County, CA 32 km (20 mi) SE of here earthquakes near San Mateo County
Santa Clara County, CA 39 km (24 mi) W of here earthquakes near Santa Clara County
Alameda County, CA 52 km (33 mi) SSW of here earthquakes near Alameda County
Contra Costa County, CA 81 km (50 mi) S of here earthquakes near Contra Costa County
San Francisco County, CA 99 km (61 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

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

  1. 1.5 10km NE of Milpitas, CA
  2. 1.5 12km ESE of Alum Rock, CA
  3. 2.0 10km NE of Milpitas, CA
  4. 2.3 10km NE of Milpitas, CA
  5. 1.8 10km E of Alum Rock, CA
  6. 1.7 14km SW of Santa Cruz, CA
  7. 1.9 0km SW of Los Gatos, CA
  8. 1.8 10km ENE of Milpitas, CA
  9. 1.8 19km WNW of Bonny Doon, CA
  10. 1.6 8km NE of Alum Rock, CA
  11. 2.1 4km WSW of Los Altos Hills, CA
  12. 2.1 10km NE of Milpitas, CA
  13. 1.6 10km NE of Milpitas, CA
  14. 2.6 8km WSW of Saratoga, CA
  15. 2.1 10km NE of Milpitas, 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 7,400 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.