QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

3km W of Bridgeport, CA

Yes. A magnitude 2.1 earthquake was recorded 3km W of Bridgeport, CA, at 11:12 pm PDT on 20 October 2018 (06:12 UTC), 1.8 km deep. 5 people have reported feeling it to USGS.

· 1.8 km deep · released about 49 lb of TNT

10 km30 km60 km120 km N Mono County 51 kmAlpine County 62 kmTuolumne County 66 kmDouglas County 78 kmMineral County 80 kmLyon County 86 kmMariposa County 95 kmCarson City 108 kmCalaveras County 113 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 2.1 (md)
Depth
1.8 km below the surface
Felt
5 reports · strongest reported intensity III
Nearest
Mono County, 51 km SE
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 2943 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. 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 49 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 310,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 220,000× the energy of this one
  3. Around the size people start to feel M 3.0 19× the energy of this one
  4. This earthquake M 2.1 about 49 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 5.6 on 2016-12-28 — about 150,000 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 · 25 km SSE of this epicentre
  2. 5.2 23 km S of Walker, California · 21 km WNW of this epicentre
  3. 5.2 31 km ENE of Mono City, California · 41 km ESE of this epicentre
  4. 5.1 23 km E of Bridgeport, California · 26 km E of this epicentre
  5. 5.1 19 km W of Bridgeport, California · 17 km WSW 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 38.2542, -119.2650. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mono County, CA 51 km (32 mi) SE earthquakes near Mono County
Alpine County, CA 62 km (38 mi) NW earthquakes near Alpine County
Tuolumne County, CA 66 km (41 mi) WSW earthquakes near Tuolumne County
Douglas County, NV 78 km (49 mi) NNW earthquakes near Douglas County
Mineral County, NV 80 km (49 mi) ENE earthquakes near Mineral County
Lyon County, NV 86 km (53 mi) N earthquakes near Lyon County

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

Aftershocks so far

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

  1. 1.9 20km SE of Bodie, CA
  2. 1.6 22 km E of Mono City, California
  3. 1.6 23 km E of Mono City, California
  4. 1.8 20km SE of Bodie, CA
  5. 2.1 19km SE of Bodie, CA
  6. 2.7 20km SE of Bodie, CA
  7. 2.3 21km SE of Bodie, CA
  8. 1.5 20 km ENE of Mono City, California
  9. 1.5 23 km E of Mono City, California
  10. 1.8 29 km WSW of Hawthorne, Nevada
  11. 1.6 35 km NE of Mono City, California
  12. 2.6 29 km WSW of Hawthorne, Nevada
  13. 2.2 30 km SW of Hawthorne, Nevada
  14. 1.5 21km SSE of Bodie, CA
  15. 1.6 21km SE of Bodie, 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.