QuakeIndex

Earthquake · reviewed by a seismologist

M 2.4md

Earthquake near San Jose, CA

No earthquake was likely felt in San Jose in the 24 hours to 3:35 pm PST (23:35 UTC). The last one was M 2.6, 19 km (12 mi) E, at 12:38 pm PDT on 27 October 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near San Jose

This page: a magnitude 2.4 earthquake was recorded 18 km (11 mi) northeast of San Jose, CA, at 4:56 am PST on 4 March 2023 (12:56 UTC), 7.4 km deep.

USGS: 12km NNE of Alum Rock, CA

19 km (12 mi) N of San Jose, CA · 11 km (7 mi) ENE of Milpitas, CA

4:56 am PST, Mar 4, 2023 · · 7.4 km deep · released about 120 lb of TNT

10 km30 km60 km120 km N Alameda County 23 kmSanta Clara County 28 kmContra Costa County 53 kmSan Mateo County 53 kmSanta Cruz County 55 kmSan Joaquin County 68 kmStanislaus County 69 kmSolano County 90 kmMerced County 98 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
4:56 am PST on 4 March 2023 ()
Where
18 km (11 mi) northeast of San Jose, CA · earthquakes near San Jose
Magnitude
M 2.4 (md)
Depth
7.4 km below the surface
Felt
no reports yet
Nearest
Alameda County, 23 km NNW
Nearest mapped fault
Calaveras fault, 4 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1346 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 20 km (12 mi) from the epicentre. In San Jose, 18 km away, the estimate is intensity II (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

Likely felt in: Milpitas 12 km, intensity II · San Jose 18 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 89,000× the energy of this one
  3. Around the size people start to feel M 3.0 7.9× the energy of this one
  4. This earthquake M 2.4 about 120 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.

For this area

The largest earthquake within 50 km since 2016 was M 5.1 on 2022-10-25 — about 9,800 times the energy of this one.

Before 2016, the USGS record lists 19 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 49 km S of this epicentre
  2. 6.5 Near Morgan Hill, California · 41 km SSE of this epicentre
  3. 6.2 Near San Jose, California · 19 km S of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 19 km SSE of this epicentre
  5. 6.1 Near San Jose, California · 30 km S of this epicentre

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 37.4670, -121.7767. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Alameda County, CA 23 km (15 mi) NNW earthquakes near Alameda County
Santa Clara County, CA 28 km (18 mi) SSE earthquakes near Santa Clara County
Contra Costa County, CA 53 km (33 mi) NNW earthquakes near Contra Costa County
San Mateo County, CA 53 km (33 mi) W earthquakes near San Mateo County
Santa Cruz County, CA 55 km (34 mi) SSW earthquakes near Santa Cruz County
San Joaquin County, CA 68 km (42 mi) NE earthquakes near San Joaquin County

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

Aftershocks so far

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

  1. 1.6 14km SSE of Livermore, CA
  2. 1.7 14km SSE of Livermore, CA
  3. 1.7 14km NE of Alum Rock, CA
  4. 2.1 6km NNE of San Leandro, CA
  5. 1.5 10km E of Alum Rock, CA
  6. 1.9 1km SSE of Diablo, CA
  7. 1.9 15km E of Seven Trees, CA
  8. 1.6 4km NNW of Diablo, CA
  9. 1.6 3km N of Danville, CA
  10. 1.6 2km E of Union City, CA
  11. 2.2 2km ENE of Union City, CA
  12. 2.3 11km ENE of Milpitas, CA
  13. 1.9 14km N of Morgan Hill, CA
  14. 2.0 14km ENE of Seven Trees, CA
  15. 1.6 16km E of Seven Trees, 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.