QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

Earthquake near Mammoth Lakes, CA

No earthquake was likely felt in Mammoth Lakes in the 24 hours to 6:35 am PST (14:35 UTC). The last one was M 2.9, 26 km (16 mi) SSE, at 3:54 am PDT on 24 October 2026, estimated intensity II (weak) in town. Every earthquake near Mammoth Lakes

This page: a magnitude 1.5 earthquake was recorded 49 km (30 mi) south of Mammoth Lakes, CA, at 8:11 pm PST on 17 December 2021 (04:11 UTC), 22 km deep.

USGS: 32km ENE of Shaver Lake, CA

87 km (54 mi) ENE of Fresno, CA

8:11 pm PST, Dec 17, 2021 · · 22 km deep · released about 5.6 lb of TNT

10 km30 km60 km120 km N Madera County 68 kmFresno County 78 kmMono County 79 kmMariposa County 92 kmTulare County 110 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
8:11 pm PST on 17 December 2021 ()
Where
49 km (30 mi) south of Mammoth Lakes, CA · earthquakes near Mammoth Lakes
Magnitude
M 1.5 (md)
Depth
22 km below the surface
Felt
no reports yet
Nearest
Madera County, 68 km W
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1779 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 Mammoth Lakes, 49 km away, the estimate is intensity I (not felt). 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 5.6 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 2,700,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,900,000× the energy of this one
  3. Around the size people start to feel M 3.0 170× the energy of this one
  4. This earthquake M 1.5 about 5.6 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 4.4 on 2020-02-01 — about 22,000 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. 6.2 9 km SW of Aspen Springs, California · 36 km NNE of this epicentre
  2. 6.1 11 km WNW of Aspen Springs, California · 44 km NNE of this epicentre
  3. 6.1 8 km W of Aspen Springs, California · 41 km NNE of this epicentre
  4. 6.1 4 km NNW of Round Valley, California · 43 km NE of this epicentre
  5. 6.0 Mammoth Lakes area, California · 46 km NNE 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 37.2078, -118.9770. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Madera County, CA 68 km (43 mi) W earthquakes near Madera County
Fresno County, CA 78 km (49 mi) SW earthquakes near Fresno County
Mono County, CA 79 km (49 mi) N earthquakes near Mono County
Mariposa County, CA 92 km (57 mi) WNW earthquakes near Mariposa County
Tulare County, CA 110 km (69 mi) S earthquakes near Tulare County
Tuolumne County, CA 126 km (78 mi) NW earthquakes near Tuolumne County

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

Aftershocks so far

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

  1. 1.9 15km WSW of Toms Place, CA
  2. 2.4 15km SW of Toms Place, CA
  3. 1.8 9km WSW of Round Valley, CA
  4. 1.6 10km SSW of Mammoth Lakes, CA
  5. 1.9 17km S of Mammoth Lakes, CA
  6. 1.7 16km S of Mammoth Lakes, CA
  7. 1.6 1km WSW of Auberry, CA
  8. 1.5 10km W of Toms Place, CA
  9. 1.6 15km SW of Toms Place, CA
  10. 1.8 16km WSW of Toms Place, CA
  11. 1.6 26km NE of North Fork, CA
  12. 1.9 10km E of Mammoth Lakes, CA
  13. 2.1 10km WSW of Toms Place, CA
  14. 2.4 15km SW of Toms Place, CA
  15. 1.7 1km NE of Round Valley, 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.