QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3md

Earthquake near East Foothills, CA

No earthquake was likely felt in East Foothills in the 24 hours to 10:34 pm PST (06:34 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 2.3 earthquake was recorded 7 km (4 mi) east of East Foothills, CA, at 9:26 am PDT on 30 August 2017 (16:26 UTC), 6.6 km deep. 1 person has reported feeling it to USGS.

USGS: 6 km E of East Foothills, California

12 km (7 mi) NE of San Jose, CA

9:26 am PDT, Aug 30, 2017 · · 6.6 km deep · released about 74 lb of TNT

10 km30 km60 km120 km N Santa Clara County 19 kmAlameda County 33 kmSanta Cruz County 48 kmSan Mateo County 56 kmContra Costa County 62 kmStanislaus County 68 kmSan Joaquin County 74 kmMerced County 92 kmSolano County 100 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
9:26 am PDT on 30 August 2017 ()
Where
7 km (4 mi) east of East Foothills, CA · earthquakes near East Foothills
Magnitude
M 2.3 (md)
Depth
6.6 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Santa Clara County, 19 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 3358 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 18 km (11 mi) from the epicentre. In East Foothills, 7 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.

Likely felt in: San Jose 15 km, intensity II · Milpitas 16 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 74 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 200,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 140,000× the energy of this one
  3. Around the size people start to feel M 3.0 13× the energy of this one
  4. This earthquake M 2.3 about 74 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 22 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 41 km SSW of this epicentre
  2. 6.5 Near Morgan Hill, California · 32 km SSE of this epicentre
  3. 6.2 Near San Jose, California · 11 km SSW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 10 km SSE of this epicentre
  5. 6.1 Near San Jose, California · 21 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 37.3848, -121.7398. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 19 km (12 mi) SSE earthquakes near Santa Clara County
Alameda County, CA 33 km (20 mi) NNW earthquakes near Alameda County
Santa Cruz County, CA 48 km (30 mi) SSW earthquakes near Santa Cruz County
San Mateo County, CA 56 km (35 mi) W earthquakes near San Mateo County
Contra Costa County, CA 62 km (39 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

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

  1. 1.6 7 km WSW of Gilroy, California
  2. 1.9 14 km E of Seven Trees, California
  3. 1.7 5 km SW of Gilroy, California
  4. 2.4 5 km SW of Gilroy, California
  5. 2.0 10 km ENE of Milpitas, California
  6. 2.4 7 km WSW of Gilroy, California
  7. 2.2 8 km ENE of San Martin, California
  8. 1.6 12 km ESE of East Foothills, California
  9. 2.7 8 km ENE of San Martin, California
  10. 2.3 5 km SW of Gilroy, California
  11. 1.6 6 km NNW of Day Valley, California
  12. 2.3 2 km SSE of Dublin, California
  13. 2.6 15 km SSE of Livermore, California
  14. 1.6 0 km S of Los Altos Hills, California
  15. 2.9 15 km SSE of Livermore, California

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.