QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8md

21km WNW of Boulder Creek, CA

· 14 km deep · released about 530 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 28 kmSanta Cruz County 35 kmSanta Clara County 59 kmAlameda County 66 kmSan Francisco County 87 kmContra Costa County 91 kmMarin County 104 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 2.8 (md)
Depth
14 km below the surface
Felt
4 reports · strongest reported intensity III
Nearest
San Mateo County, 28 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2718 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 4 people have reported feeling it to USGS.

How big was it?

This earthquake released about 530 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 29,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 20,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.8× the energy of this one
  4. This earthquake M 2.8 about 530 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 37.1675, -122.3515. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Mateo County, CA 28 km (17 mi) S of here earthquakes near San Mateo County
Santa Cruz County, CA 35 km (22 mi) WNW of here earthquakes near Santa Cruz County
Santa Clara County, CA 59 km (37 mi) W of here earthquakes near Santa Clara County
Alameda County, CA 66 km (41 mi) SW of here earthquakes near Alameda County
San Francisco County, CA 87 km (54 mi) SE of here earthquakes near San Francisco County
Contra Costa County, CA 91 km (56 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

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

  1. 1.6 3km W of Portola Valley, CA
  2. 1.9 3km W of Portola Valley, CA
  3. 2.7 3km W of Portola Valley, CA
  4. 1.7 3km W of Portola Valley, CA
  5. 1.5 9km N of Boulder Creek, CA
  6. 1.7 3km W of Portola Valley, CA
  7. 1.8 3km W of Portola Valley, CA
  8. 1.8 2km SW of Los Altos Hills, CA
  9. 2.2 5km SSE of Newark, CA
  10. 1.8 12km WNW of Boulder Creek, CA
  11. 1.7 3km SW of Lexington Hills, CA
  12. 1.9 14km SW of Santa Cruz, CA
  13. 1.8 30km SW of Bonny Doon, CA
  14. 1.7 2km ESE of Woodside, CA
  15. 1.7 6km SSE of Portola Valley, 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.