QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8md

Earthquake near San Jose, CA

No earthquake was likely felt in San Jose in the 24 hours to 9:28 pm PST (05:28 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 2.8 earthquake was recorded 17 km (11 mi) east of San Jose, CA, at 8:21 pm PDT on 27 October 2023 (03:21 UTC), 8.2 km deep. 74 people have reported feeling it to USGS.

USGS: 11 km ESE of Alum Rock, CA

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

8:21 pm PDT, Oct 27, 2023 · · 8.2 km deep · released about 510 lb of TNT

10 km30 km60 km120 km N Santa Clara County 14 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 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
8:21 pm PDT on 27 October 2023 ()
Where
17 km (11 mi) east of San Jose, CA · earthquakes near San Jose
Magnitude
M 2.8 (md)
Depth
8.2 km below the surface
Felt
74 reports · strongest reported intensity IV
Nearest
Santa Clara County, 14 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 1043 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 27 km (17 mi) from the epicentre. In San Jose, 17 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 17 km, intensity II · Milpitas 20 km, intensity II · Santa Clara 22 km, intensity II · Campbell 23 km, intensity II · Morgan Hill 24 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 510 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 30,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 21,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.9× the energy of this one
  4. This earthquake M 2.8 about 510 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 2,300 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 · 38 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 37.3437, -121.7010. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 14 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 (42 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

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

  1. 1.5 9 km NE of Alum Rock, CA
  2. 3.2 7 km E of Fremont, CA
  3. 1.6 6 km SSW of Gilroy, CA
  4. 1.6 2 km E of Hayward, CA
  5. 2.5 8 km NE of Interlaken, CA
  6. 2.2 3 km ESE of Woodside, CA
  7. 1.5 6 km S of Portola Valley, CA
  8. 2.3 3 km ESE of Woodside, CA
  9. 1.5 11 km WSW of Patterson, CA
  10. 2.7 15 km SW of Westley, CA
  11. 1.6 4 km NE of Portola Valley, CA
  12. 1.6 15 km N of Morgan Hill, CA
  13. 1.7 20 km WSW of Patterson, CA
  14. 2.1 5 km ESE of Interlaken, CA
  15. 3.3 5 km ESE of Interlaken, 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.