QuakeIndex

Earthquake · reviewed by a seismologist

M 3.2ml

13km WSW of Bridgeport, CA

Yes. A magnitude 3.2 earthquake was recorded 13km WSW of Bridgeport, CA, at 7:14 am PDT on 28 July 2021 (14:14 UTC), 11 km deep. 8 people have reported feeling it to USGS.

· 11 km deep · released about 1,800 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Tuolumne County 56 kmMono County 56 kmAlpine County 57 kmDouglas County 78 kmMariposa County 87 kmLyon County 90 kmMineral County 90 kmCalaveras County 103 kmCarson City 108 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
Magnitude
M 3.2 (ml)
Depth
11 km below the surface
Felt
8 reports · strongest reported intensity III
Nearest
Tuolumne County, 56 km WSW
Nearest mapped fault
Robinson Creek fault, 5 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 1867 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 44 km (27 mi) from the epicentre. 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.

How big was it?

This earthquake released about 1,800 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 190,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 8,500× the energy of this one
  3. Magna, Utah 2020 M 5.7 6,000× the energy of this one
  4. This earthquake M 3.2 about 1,800 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.9× more

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 6.0 on 2021-07-08 — about 17,000 times the energy of this one.

Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.8 3 km NE of Mono City, California · 29 km SE of this epicentre
  2. 5.2 23 km S of Walker, California · 13 km NW of this epicentre
  3. 5.2 31 km ENE of Mono City, California · 50 km E of this epicentre
  4. 5.1 23 km E of Bridgeport, California · 36 km E of this epicentre
  5. 5.1 19 km W of Bridgeport, California · 7 km W 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 38.2298, -119.3795. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Tuolumne County, CA 56 km (35 mi) WSW earthquakes near Tuolumne County
Mono County, CA 56 km (35 mi) SE earthquakes near Mono County
Alpine County, CA 57 km (35 mi) NW earthquakes near Alpine County
Douglas County, NV 78 km (48 mi) NNW earthquakes near Douglas County
Mariposa County, CA 87 km (54 mi) SSW earthquakes near Mariposa County
Lyon County, NV 90 km (56 mi) N earthquakes near Lyon County

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

Aftershocks so far

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

  1. 2.2 28km S of Smith Valley, NV
  2. 1.5 32km SE of Markleeville, CA
  3. 2.4 26km ENE of Dardanelle, CA
  4. 2.3 30km SSW of Smith Valley, NV
  5. 2.1 25km ENE of Dardanelle, CA
  6. 1.6 25km ENE of Dardanelle, CA
  7. 2.5 25km ENE of Dardanelle, CA
  8. 2.7 32km SSW of Smith Valley, NV
  9. 1.8 30km SE of Markleeville, CA
  10. 1.8 25km ENE of Dardanelle, CA
  11. 2.3 25km ENE of Dardanelle, CA
  12. 1.6 25km ENE of Dardanelle, CA
  13. 1.6 25km ENE of Dardanelle, CA
  14. 1.6 25km ENE of Dardanelle, CA
  15. 1.6 25km ENE of Dardanelle, 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.