QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near San Jose, CA

No earthquake was likely felt in San Jose in the 24 hours to 3:53 pm PST (23:53 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 1.6 earthquake was recorded 22 km (14 mi) northeast of San Jose, CA, at 2:19 am PDT on 18 May 2021 (09:19 UTC), 2.7 km deep.

USGS: 16km NE of Alum Rock, CA

21 km (13 mi) NNE of San Jose, CA · 18 km (11 mi) E of Milpitas, CA

2:19 am PDT, May 18, 2021 · · 2.7 km deep · released about 8.4 lb of TNT

10 km30 km60 km120 km N Santa Clara County 26 kmAlameda County 29 kmSanta Cruz County 57 kmContra Costa County 57 kmSan Mateo County 60 kmStanislaus County 62 kmSan Joaquin County 65 kmMerced County 90 kmSolano County 93 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
2:19 am PDT on 18 May 2021 ()
Where
22 km (14 mi) northeast of San Jose, CA · earthquakes near San Jose
Magnitude
M 1.6 (md)
Depth
2.7 km below the surface
Felt
no reports yet
Nearest
Santa Clara County, 26 km S
Nearest mapped fault
Calaveras fault, 9 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 2002 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 11 km (7 mi) from the epicentre. In San Jose, 22 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.

Earthquakes near other towns within 30 km: East Foothills, Milpitas, Santa Clara, Livermore, Fremont, Pleasanton.

How big was it?

This earthquake released about 8.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,300,000× the energy of this one
  3. Around the size people start to feel M 3.0 110× the energy of this one
  4. This earthquake M 1.6 about 8.4 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 4.3 on 2019-07-16 — about 10,000 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 SSW of this epicentre
  2. 6.5 Near Morgan Hill, California · 38 km S of this epicentre
  3. 6.2 Near San Jose, California · 20 km SSW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 16 km S of this epicentre
  5. 6.1 Near San Jose, California · 30 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 37.4533, -121.6905. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 26 km (16 mi) S earthquakes near Santa Clara County
Alameda County, CA 29 km (18 mi) NW earthquakes near Alameda County
Santa Cruz County, CA 57 km (35 mi) SSW earthquakes near Santa Cruz County
Contra Costa County, CA 57 km (35 mi) NNW earthquakes near Contra Costa County
San Mateo County, CA 60 km (37 mi) W earthquakes near San Mateo County
Stanislaus County, CA 62 km (38 mi) ENE earthquakes near Stanislaus 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. 2.2 9km NE of Gilroy, CA
  2. 1.9 11km NE of Milpitas, CA
  3. 2.2 9km ENE of San Martin, CA
  4. 2.9 15km E of Seven Trees, CA
  5. 2.2 4km NNE of Blackhawk, CA
  6. 2.5 4km NNE of Blackhawk, CA
  7. 2.0 4km NE of Blackhawk, CA
  8. 1.5 16km SSE of Livermore, CA
  9. 1.6 9km WSW of Mountain House, CA
  10. 1.8 5km E of Fremont, CA
  11. 1.7 3km NNW of Byron, CA
  12. 1.6 13km N of Morgan Hill, CA
  13. 1.8 8km SW of Loyola, CA
  14. 1.7 9km NNE of Alum Rock, CA
  15. 1.7 19km SE of Livermore, 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.