QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

Earthquake near East Foothills, CA

No earthquake was likely felt in East Foothills in the 24 hours to 11:38 pm PST (07:38 UTC). The last one was M 2.9, 32 km (20 mi) E, at 9:44 am PDT on 31 October 2026, estimated intensity II (weak) in town. Every earthquake near East Foothills

This page: a magnitude 1.5 earthquake was recorded 12 km (7 mi) east-southeast of East Foothills, CA, at 9:05 pm PST on 21 November 2017 (05:05 UTC), 7.6 km deep.

USGS: 11 km ESE of East Foothills, California

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

9:05 pm PST, Nov 21, 2017 · · 7.6 km deep · released about 6.2 lb of TNT

10 km30 km60 km120 km N Santa Clara County 13 kmAlameda County 40 kmSanta Cruz County 45 kmSan Mateo County 60 kmStanislaus County 66 kmContra Costa County 69 kmSan Joaquin County 77 kmMerced County 88 kmSan Benito County 97 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
9:05 pm PST on 21 November 2017 ()
Where
12 km (7 mi) east-southeast of East Foothills, CA · earthquakes near East Foothills
Magnitude
M 1.5 (md)
Depth
7.6 km below the surface
Felt
no reports yet
Nearest
Santa Clara County, 13 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 3269 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 East Foothills, 12 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: San Jose, Milpitas, Santa Clara, Campbell, Morgan Hill, Los Gatos.

How big was it?

This earthquake released about 6.2 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,700,000× the energy of this one
  3. Around the size people start to feel M 3.0 150× the energy of this one
  4. This earthquake M 1.5 about 6.2 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 6,700 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 · 37 km SSW of this epicentre
  2. 6.5 Near Morgan Hill, California · 25 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 · 3 km SSE of this epicentre
  5. 6.1 Near San Jose, California · 17 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 37.3348, -121.6987. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 13 km (8 mi) S earthquakes near Santa Clara County
Alameda County, CA 40 km (25 mi) NNW earthquakes near Alameda County
Santa Cruz County, CA 45 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 69 km (43 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

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

  1. 1.6 6km SW of Gilroy, CA
  2. 1.8 9km E of Livermore, CA
  3. 2.0 12km SSW of Mountain House, CA
  4. 1.7 7km WNW of Lexington Hills, CA
  5. 2.5 8km ENE of San Martin, CA
  6. 1.8 11km NNW of Hollister, CA
  7. 2.9 16km E of Seven Trees, CA
  8. 2.8 6km ESE of Interlaken, CA
  9. 1.6 10km NNE of Alum Rock, CA
  10. 2.0 15km E of Seven Trees, CA
  11. 2.6 6km NNW of Aromas, CA
  12. 3.6 6km NNW of Aromas, CA
  13. 2.1 6km S of Gilroy, CA
  14. 1.7 4km SW of Stanford, CA
  15. 2.1 11km SSW of Loyola, 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.