QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near Saratoga, CA

No earthquake was likely felt in Saratoga in the 24 hours to 10:48 pm PST (06:48 UTC). The last one was M 2.0, 7 km (4 mi) NW, at 9:23 am PST on 10 November 2026, estimated intensity II (weak) in town; 4 felt reports to USGS. Every earthquake near Saratoga

This page: a magnitude 1.6 earthquake was recorded 11 km (7 mi) west-southwest of Saratoga, CA, at 11:36 am PDT on 10 October 2021 (18:36 UTC), 8.4 km deep.

USGS: 11km WSW of Saratoga, CA

30 km (19 mi) WSW of San Jose, CA · 13 km (8 mi) SW of Cupertino, CA

11:36 am PDT, Oct 10, 2021 · · 8.4 km deep · released about 7.6 lb of TNT

10 km30 km60 km120 km N Santa Cruz County 28 kmSan Mateo County 28 kmSanta Clara County 40 kmAlameda County 50 kmContra Costa County 78 kmSan Francisco County 95 kmMarin County 105 kmStanislaus County 107 kmSan Joaquin County 109 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
11:36 am PDT on 10 October 2021 ()
Where
11 km (7 mi) west-southwest of Saratoga, CA · earthquakes near Saratoga
Magnitude
M 1.6 (md)
Depth
8.4 km below the surface
Felt
no reports yet
Nearest
Santa Cruz County, 28 km SSE
Nearest mapped fault
Butano 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 1858 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 7 km (4 mi) from the epicentre. In Saratoga, 11 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: Boulder Creek, Loyola, Monte Sereno, Cupertino, Los Gatos, Brookdale.

How big was it?

This earthquake released about 7.6 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 2,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
  3. Around the size people start to feel M 3.0 130× the energy of this one
  4. This earthquake M 1.6 about 7.6 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 5,400 times the energy of this one.

Before 2016, the USGS record lists 21 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 33 km SE of this epicentre
  2. 6.5 Near Morgan Hill, California · 47 km ESE of this epicentre
  3. 6.3 22 km S of Davenport, California · 48 km S of this epicentre
  4. 6.3 16 km SW of Davenport, California · 39 km SSW of this epicentre
  5. 6.2 Near San Jose, California · 31 km ENE 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 37.2392, -122.1442. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Cruz County, CA 28 km (17 mi) SSE earthquakes near Santa Cruz County
San Mateo County, CA 28 km (17 mi) NW earthquakes near San Mateo County
Santa Clara County, CA 40 km (25 mi) E earthquakes near Santa Clara County
Alameda County, CA 50 km (31 mi) NNE earthquakes near Alameda County
Contra Costa County, CA 78 km (48 mi) NNE earthquakes near Contra Costa County
San Francisco County, CA 95 km (59 mi) NW earthquakes near San Francisco County

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

Aftershocks so far

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

  1. 1.6 2km ESE of Hayward, CA
  2. 3.6 4km ENE of Corralitos, CA
  3. 1.5 12km ESE of Alum Rock, CA
  4. 2.0 8km ENE of Milpitas, CA
  5. 1.7 22km W of Bonny Doon, CA
  6. 1.7 9km ENE of Alum Rock, CA
  7. 1.6 10km NNE of Alum Rock, CA
  8. 1.6 8km NNE of Milpitas, CA
  9. 2.7 5km SSW of Lexington Hills, CA
  10. 1.6 4km E of South San Francisco, CA
  11. 1.9 12km ESE of Alum Rock, CA
  12. 1.9 8km E of Alum Rock, CA
  13. 1.6 2km NE of Union City, CA
  14. 2.7 16km E of Seven Trees, CA
  15. 1.9 16km E of Seven Trees, 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.