QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

Earthquake near Phoenix Lake, CA

No earthquake was likely felt in Phoenix Lake in the 24 hours to 9:12 am PST (17:12 UTC). The last one was M 5.2, 181 km (113 mi) NE, at 1:17 am PDT on 1 May 2026, estimated intensity II (weak) in town; 1,875 felt reports to USGS. Every earthquake near Phoenix Lake

This page: a magnitude 2.1 earthquake was recorded 28 km (17 mi) southeast of Phoenix Lake, CA, at 10:18 am PDT on 25 August 2021 (17:18 UTC), 38 km deep.

USGS: 11km E of Groveland-Big Oak Flat, CA

10:18 am PDT, Aug 25, 2021 · · 38 km deep · released about 46 lb of TNT

10 km30 km60 km120 km N Tuolumne County 24 kmMariposa County 32 kmCalaveras County 58 kmMadera County 75 kmAmador County 85 kmStanislaus County 86 kmMerced County 91 kmAlpine County 91 kmSan Joaquin County 105 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
10:18 am PDT on 25 August 2021 ()
Where
28 km (17 mi) southeast of Phoenix Lake, CA · earthquakes near Phoenix Lake
Magnitude
M 2.1 (md)
Depth
38 km below the surface
Felt
no reports yet
Nearest
Tuolumne County, 24 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1900 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. In Phoenix Lake, 28 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: Tuolumne City, Soulsbyville, Mono Vista, Twain Harte, East Sonora.

How big was it?

This earthquake released about 46 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 5.8 330,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 230,000× the energy of this one
  3. Around the size people start to feel M 3.0 21× the energy of this one
  4. This earthquake M 2.1 about 46 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 since 1900 lists no earthquake of M5 or more within 50 km.

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 37.8297, -120.0797. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Tuolumne County, CA 24 km (15 mi) NNE earthquakes near Tuolumne County
Mariposa County, CA 32 km (20 mi) SSE earthquakes near Mariposa County
Calaveras County, CA 58 km (36 mi) NW earthquakes near Calaveras County
Madera County, CA 75 km (46 mi) SSE earthquakes near Madera County
Amador County, CA 85 km (53 mi) NW earthquakes near Amador County
Stanislaus County, CA 86 km (54 mi) WSW earthquakes near Stanislaus County

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

Aftershocks so far

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

  1. 2.1 11 km SSW of Mariposa, CA
  2. 2.2 9 km NW of Chinese Camp, CA
  3. 2.2 11 km SSW of Mariposa, CA
  4. 1.6 8 km SSW of Mariposa, CA
  5. 2.2 10 km SSW of Mariposa, CA
  6. 2.1 20 km ENE of Mi-Wuk Village, CA
  7. 2.3 15 km SW of Mariposa, CA
  8. 2.4 9 km SSW of Mariposa, CA
  9. 2.4 7 km SSW of Mariposa, CA
  10. 2.3 10 km SSW of Mariposa, CA
  11. 2.3 10 km SSW of Mariposa, CA
  12. 2.0 10 km SSW of Mariposa, CA
  13. 2.3 11 km SSW of Mariposa, CA
  14. 2.8 10 km SSW of Mariposa, CA
  15. 2.0 9 km SSW of Mariposa, 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.