QuakeIndex

Earthquake · reviewed by a seismologist

M 2.6mh

Earthquake near Mammoth Lakes, CA

No earthquake was likely felt in Mammoth Lakes in the 24 hours to 7:28 am PST (15:28 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 2.6 earthquake was recorded 12 km (7 mi) south of Mammoth Lakes, CA, at 5:23 pm PDT on 18 August 2021 (00:23 UTC), 12 km deep.

USGS: 11km S of Mammoth Lakes, CA

5:23 pm PDT, Aug 18, 2021 · · 12 km deep · released about 240 lb of TNT

10 km30 km60 km120 km N Mono County 43 kmMadera County 77 kmMariposa County 81 kmTuolumne County 101 kmFresno County 105 kmMineral County 120 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
5:23 pm PDT on 18 August 2021 ()
Where
12 km (7 mi) south of Mammoth Lakes, CA · earthquakes near Mammoth Lakes
Magnitude
M 2.6 (mh)
Depth
12 km below the surface
Felt
no reports yet
Nearest
Mono County, 43 km NNE
Nearest mapped fault
Hilton Creek fault, 13 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 1908 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 20 km (12 mi) from the epicentre. In Mammoth Lakes, 12 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: Mammoth Lakes 12 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 240 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 63,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 45,000× the energy of this one
  3. Around the size people start to feel M 3.0 4× the energy of this one
  4. This earthquake M 2.6 about 240 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 520 times the energy of this one.

Before 2016, the USGS record lists 31 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.4 The 1986 Chalfant Valley, California Earthquake · 48 km E of this epicentre
  2. 6.2 9 km SW of Aspen Springs, California · 17 km ESE of this epicentre
  3. 6.1 11 km WNW of Aspen Springs, California · 15 km ENE of this epicentre
  4. 6.1 8 km W of Aspen Springs, California · 16 km E of this epicentre
  5. 6.1 4 km NNW of Round Valley, California · 35 km ESE 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 37.5418, -118.9915. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mono County, CA 43 km (27 mi) NNE earthquakes near Mono County
Madera County, CA 77 km (48 mi) WSW earthquakes near Madera County
Mariposa County, CA 81 km (50 mi) W earthquakes near Mariposa County
Tuolumne County, CA 101 km (63 mi) WNW earthquakes near Tuolumne County
Fresno County, CA 105 km (65 mi) SW earthquakes near Fresno County
Mineral County, NV 120 km (74 mi) NNE earthquakes near Mineral County

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

Aftershocks so far

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

  1. 1.6 9km W of Toms Place, CA
  2. 1.9 7km E of Mammoth Lakes, CA
  3. 2.1 7km E of Mammoth Lakes, CA
  4. 2.8 10km SW of Toms Place, CA
  5. 1.5 7km NW of West Bishop, CA
  6. 2.1 12km W of Toms Place, CA
  7. 2.0 12km W of Toms Place, CA
  8. 1.5 16km ESE of Yosemite Valley, CA
  9. 2.7 6km NE of Round Valley, CA
  10. 1.8 20km ESE of Yosemite Valley, CA
  11. 1.5 17km SSE of Mammoth Lakes, CA
  12. 1.8 16km SE of Mammoth Lakes, CA
  13. 2.1 9km WSW of Toms Place, CA
  14. 1.9 16km SW of Toms Place, CA
  15. 1.7 16km SW of Toms Place, 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.