QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9mw

Earthquake near San Jose, CA

No earthquake was likely felt in San Jose in the 24 hours to 2:31 am PST (10:31 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 3.9 earthquake was recorded 15 km (9 mi) east-northeast of San Jose, CA, at 10:32 pm PST on 26 December 2017 (06:32 UTC), 11 km deep. 9,208 people have reported feeling it to USGS.

USGS: 8km ENE of Alum Rock, CA

13 km (8 mi) NNE of San Jose, CA

10:32 pm PST, Dec 26, 2017 · · 11 km deep · released about 11 tons of TNT

Every earthquake near San Jose Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Clara County 20 kmAlameda County 31 kmSanta Cruz County 49 kmSan Mateo County 55 kmContra Costa County 61 kmStanislaus County 68 kmSan Joaquin County 73 kmMerced County 93 kmSolano 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
10:32 pm PST on 26 December 2017 ()
Where
15 km (9 mi) east-northeast of San Jose, CA · earthquakes near San Jose
Magnitude
M 3.9 (mw)
Depth
11 km below the surface
Felt
9,208 reports · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
Nearest
Santa Clara County, 20 km SSE
Nearest mapped fault
Calaveras fault, 2 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 2585 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 89 km (55 mi) from the epicentre. In San Jose, 15 km away, the estimate is intensity III (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 15 km, intensity III · San Jose 15 km, intensity III · Santa Clara 19 km, intensity III · Campbell 22 km, intensity III · Sunnyvale 26 km, intensity III · Cupertino 27 km, intensity III · Fremont 27 km, intensity III · Los Gatos 28 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 16,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
  3. Magna, Utah 2020 M 5.7 500× the energy of this one
  4. This earthquake M 3.9 about 11 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 22× more

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 4.1 on 2017-10-10 — about 1.9 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 · 42 km SSW of this epicentre
  2. 6.5 Near Morgan Hill, California · 33 km SSE of this epicentre
  3. 6.2 Near San Jose, California · 12 km SSW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 11 km SSE of this epicentre
  5. 6.1 Near San Jose, California · 22 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 37.3965, -121.7468. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 20 km (12 mi) SSE earthquakes near Santa Clara County
Alameda County, CA 31 km (20 mi) NNW earthquakes near Alameda County
Santa Cruz County, CA 49 km (30 mi) SSW earthquakes near Santa Cruz County
San Mateo County, CA 55 km (34 mi) W earthquakes near San Mateo County
Contra Costa County, CA 61 km (38 mi) NNW earthquakes near Contra Costa County
Stanislaus County, CA 68 km (42 mi) ENE earthquakes near Stanislaus County

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

Aftershocks so far

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

  1. 1.7 6km E of Fremont, CA
  2. 1.8 9km ENE of Milpitas, CA
  3. 1.6 6km SW of Gilroy, CA
  4. 1.8 9km E of Livermore, CA
  5. 2.0 12km SSW of Mountain House, CA
  6. 1.7 7km WNW of Lexington Hills, CA
  7. 2.5 8km ENE of San Martin, CA
  8. 2.9 16km E of Seven Trees, CA
  9. 1.6 10km NNE of Alum Rock, CA
  10. 2.0 15km E of Seven Trees, CA
  11. 1.7 4km SW of Stanford, CA
  12. 2.1 11km SSW of Loyola, CA
  13. 2.0 8km SW of Los Altos Hills, CA
  14. 3.0 16km N of Morgan Hill, CA
  15. 1.6 7km WSW 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.