QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5md

Earthquake near San Jose, CA

No earthquake was likely felt in San Jose in the 24 hours to 1:47 pm PST (21:47 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 2.5 earthquake was recorded 18 km (11 mi) east of San Jose, CA, at 3:21 am PDT on 9 April 2023 (10:21 UTC), 8.0 km deep. 8 people have reported feeling it to USGS.

USGS: 12km ESE of Alum Rock, CA

11 km (7 mi) ENE of San Jose, CA

3:21 am PDT, Apr 9, 2023 · · 8.0 km deep · released about 190 lb of TNT

10 km30 km60 km120 km N Santa Clara County 13 kmAlameda County 39 kmSanta Cruz County 46 kmSan Mateo County 60 kmStanislaus County 66 kmContra Costa County 68 kmSan Joaquin County 76 kmMerced County 88 kmSan Benito County 97 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
3:21 am PDT on 9 April 2023 ()
Where
18 km (11 mi) east of San Jose, CA · earthquakes near San Jose
Magnitude
M 2.5 (md)
Depth
8.0 km below the surface
Felt
8 reports · strongest reported intensity III
Nearest
Santa Clara County, 13 km S
Nearest mapped fault
Calaveras fault, under 1 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 1243 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 21 km (13 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: San Jose 18 km, intensity II · Milpitas 21 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 190 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 80,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 57,000× the energy of this one
  3. Around the size people start to feel M 3.0 5.1× the energy of this one
  4. This earthquake M 2.5 about 190 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 6,200 times the energy of this one.

Before 2016, the USGS record lists 23 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 37 km SSW of this epicentre
  2. 6.5 Near Morgan Hill, California · 26 km SSE of this epicentre
  3. 6.2 Near San Jose, California · 10 km WSW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 4 km SSE of this epicentre
  5. 6.1 Near San Jose, California · 18 km SSW 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 37.3383, -121.6970. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 13 km (8 mi) S earthquakes near Santa Clara County
Alameda County, CA 39 km (24 mi) NNW earthquakes near Alameda County
Santa Cruz County, CA 46 km (28 mi) SW earthquakes near Santa Cruz County
San Mateo County, CA 60 km (37 mi) W earthquakes near San Mateo County
Stanislaus County, CA 66 km (41 mi) ENE earthquakes near Stanislaus County
Contra Costa County, CA 68 km (43 mi) NNW earthquakes near Contra Costa County

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

Aftershocks so far

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

  1. 2.0 2km SE of Portola Valley, CA
  2. 1.9 7km SSE of Portola Valley, CA
  3. 2.1 7km SSE of Portola Valley, CA
  4. 1.8 6km E of Milpitas, CA
  5. 2.4 8km NE of Gilroy, CA
  6. 1.6 10km NE of Morgan Hill, CA
  7. 1.9 13km NNE of Morgan Hill, CA
  8. 1.6 13km ESE of Gilroy, CA
  9. 2.6 7km WSW of Gilroy, CA
  10. 1.9 11km NNW of Hollister, CA
  11. 2.6 6km SSW of Gilroy, CA
  12. 1.7 10km NNE of Alum Rock, CA
  13. 1.9 5km NNW of Day Valley, CA
  14. 1.6 13km ESE of Gilroy, CA
  15. 1.7 12km ESE of Gilroy, 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.