QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

Earthquake near Mammoth Lakes, CA

No earthquake was likely felt in Mammoth Lakes in the 24 hours to 10:35 am PST (18:35 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 1.9 earthquake was recorded 39 km (24 mi) southwest of Mammoth Lakes, CA, at 10:16 am PST on 4 January 2021 (18:16 UTC), 24 km deep. 2 people have reported feeling it to USGS.

USGS: 29km ENE of North Fork, CA

82 km (51 mi) NE of Fresno, CA

10:16 am PST, Jan 4, 2021 · · 24 km deep · released about 21 lb of TNT

10 km30 km60 km120 km N Madera County 49 kmMariposa County 64 kmMono County 69 kmFresno County 77 kmTuolumne County 97 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
10:16 am PST on 4 January 2021 ()
Where
39 km (24 mi) southwest of Mammoth Lakes, CA · earthquakes near Mammoth Lakes
Magnitude
M 1.9 (md)
Depth
24 km below the surface
Felt
2 reports · strongest reported intensity II
Nearest
Madera County, 49 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1557 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, 39 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 21 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 710,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 500,000× the energy of this one
  3. Around the size people start to feel M 3.0 45× the energy of this one
  4. This earthquake M 1.9 about 21 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 5,800 times the energy of this one.

Before 2016, the USGS record lists 20 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 9 km SW of Aspen Springs, California · 41 km ENE of this epicentre
  2. 6.1 11 km WNW of Aspen Springs, California · 43 km NE of this epicentre
  3. 6.1 8 km W of Aspen Springs, California · 43 km ENE of this epicentre
  4. 6.0 Mammoth Lakes area, California · 50 km ENE of this epicentre
  5. 6.0 Mammoth Lakes area, California · 50 km ENE 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 37.3650, -119.2335. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Madera County, CA 49 km (30 mi) WSW earthquakes near Madera County
Mariposa County, CA 64 km (40 mi) WNW earthquakes near Mariposa County
Mono County, CA 69 km (43 mi) NNE earthquakes near Mono County
Fresno County, CA 77 km (48 mi) SSW earthquakes near Fresno County
Tuolumne County, CA 97 km (60 mi) NW earthquakes near Tuolumne County
Calaveras County, CA 148 km (92 mi) NW earthquakes near Calaveras County

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

Aftershocks so far

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

  1. 1.5 11km WNW of Toms Place, CA
  2. 1.9 14km SE of Mammoth Lakes, CA
  3. 1.6 22km ESE of Yosemite Valley, CA
  4. 2.4 7km SE of North Fork, CA
  5. 1.9 18km SSE of Shaver Lake, CA
  6. 1.6 8km ESE of Mammoth Lakes, CA
  7. 2.3 8km ESE of Mammoth Lakes, CA
  8. 2.0 13km WNW of Round Valley, CA
  9. 1.9 9km E of Mammoth Lakes, CA
  10. 2.8 18km SSE of Shaver Lake, CA
  11. 1.6 21km SE of Yosemite Valley, CA
  12. 1.7 12km ESE of Mammoth Lakes, CA
  13. 2.9 14km S of Mammoth Lakes, CA
  14. 1.9 17km WSW of Toms Place, CA
  15. 2.3 24km NNE of Squaw 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.