QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near San Jose, CA

No earthquake was likely felt in San Jose in the 24 hours to 4:59 am PST (12:59 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 1.8 earthquake was recorded 39 km (24 mi) east-northeast of San Jose, CA, at 3:00 am PDT on 26 March 2018 (10:00 UTC), 5.5 km deep. 2 people have reported feeling it to USGS.

USGS: 27km WSW of Westley, CA

35 km (22 mi) NE of San Jose, CA · 27 km (17 mi) S of Tracy, CA

3:00 am PDT, Mar 26, 2018 · · 5.5 km deep · released about 15 lb of TNT

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
3:00 am PDT on 26 March 2018 ()
Where
39 km (24 mi) east-northeast of San Jose, CA · earthquakes near San Jose
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
Nearest mapped fault
Greenville 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 3150 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 12 km (7 mi) from the epicentre. In San Jose, 39 km away, the estimate is intensity I (not felt). 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.

Earthquakes near other towns within 30 km: Tracy.

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.

For this area

The largest earthquake within 50 km since 2016 was M 4.1 on 2017-10-10 — about 2,700 times the energy of this one.

Before 2016, the USGS record lists 11 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.5 Near Morgan Hill, California · 44 km SSW of this epicentre
  2. 6.2 Near San Jose, California · 34 km SW of this epicentre
  3. 6.2 The 1984 Morgan Hill, California Earthquake · 25 km SW of this epicentre
  4. 6.1 Near San Jose, California · 42 km SW of this epicentre
  5. 5.8 The 1979 Coyote Lake, California Earthquake · 43 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 37.4860, -121.4953. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 34 km (21 mi) SSW earthquakes near Santa Clara County
Alameda County, CA 41 km (25 mi) WNW earthquakes near Alameda County
Stanislaus County, CA 44 km (27 mi) E earthquakes near Stanislaus County
San Joaquin County, CA 54 km (33 mi) NNE earthquakes near San Joaquin County
Contra Costa County, CA 63 km (39 mi) NW earthquakes near Contra Costa County
Santa Cruz County, CA 70 km (43 mi) SW 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.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.