QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0ml

128 km SSW of McCarthy, Alaska

Yes. A magnitude 3.0 earthquake was recorded 128 km SSW of McCarthy, Alaska at 02:56 UTC on 2025-11-21, 3.8 km deep.

· 3.8 km deep · released about 870 lb of TNT

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10 km30 km60 km120 km N
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 3.0 (ml)
Depth
3.8 km below the surface
Felt
no reports yet
Nearest mapped fault
Kosakuts fault (Chugach-St. Elias fold and thrust belt), 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 266 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 35 km (22 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 870 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 390,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 17,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 12,000× the energy of this one
  4. This earthquake M 3.0 about 870 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 4.3 on 2020-08-09 — about 97 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.2 90 km SSW of McCarthy, Alaska · 49 km NNW 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 60.3019, -143.4048. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.6 106 km E of Cordova, Alaska
  2. 1.7 109 km S of McCarthy, Alaska
  3. 2.2 115 km ESE of Cordova, Alaska
  4. 1.6 121 km ESE of Cordova, Alaska
  5. 1.5 107 km S of McCarthy, Alaska
  6. 1.7 106 km S of McCarthy, Alaska
  7. 1.6 109 km S of McCarthy, Alaska
  8. 3.2 82 km S of McCarthy, Alaska
  9. 3.3 81 km S of McCarthy, Alaska
  10. 1.9 107 km S of McCarthy, Alaska
  11. 1.9 88 km S of McCarthy, Alaska
  12. 1.9 102 km S of McCarthy, Alaska
  13. 1.8 129 km S of McCarthy, Alaska
  14. 1.6 115 km S of McCarthy, Alaska
  15. 1.8 130 km S of McCarthy, Alaska

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.