QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

27km WSW of Westley, CA

· 5.5 km deep · released about 15 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Clara County 34 kmAlameda County 41 kmStanislaus County 44 kmSan Joaquin County 54 kmContra Costa County 63 kmSanta Cruz County 70 kmMerced County 76 kmSan Mateo County 78 kmSolano County 95 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 1.8 (md)
Depth
5.5 km below the surface
Felt
2 reports · strongest reported intensity II
Nearest
Santa Clara County, 34 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3103 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 2 people have reported feeling it to USGS.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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 37.4860, -121.4953. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Santa Clara County, CA 34 km (21 mi) NNE of here earthquakes near Santa Clara County
Alameda County, CA 41 km (25 mi) ESE of here earthquakes near Alameda County
Stanislaus County, CA 44 km (27 mi) W of here earthquakes near Stanislaus County
San Joaquin County, CA 54 km (33 mi) SSW of here earthquakes near San Joaquin County
Contra Costa County, CA 63 km (39 mi) SE of here earthquakes near Contra Costa County
Santa Cruz County, CA 70 km (43 mi) NE of here earthquakes near Santa Cruz County

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

Aftershocks so far

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

  1. 3.0 16km E of Seven Trees, CA
  2. 1.7 4km ESE of Union City, CA
  3. 2.3 9km ENE of San Martin, CA
  4. 2.0 15km N of Morgan Hill, CA
  5. 3.1 14km N of Morgan Hill, CA
  6. 1.9 13km SE of Livermore, CA
  7. 1.6 8km E of Alum Rock, CA
  8. 1.9 9km NNE of Alum Rock, CA
  9. 1.5 13km SE of Livermore, CA
  10. 1.8 13km SE of Livermore, CA
  11. 2.3 14km N of Morgan Hill, CA
  12. 1.7 9km NE of Milpitas, CA
  13. 1.5 7km NE of Alum Rock, CA
  14. 2.3 14km SSW of Westley, CA
  15. 1.6 14km SSW of Westley, 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 2,700 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.