QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

103 km E of McCarthy, Alaska

Yes. A magnitude 1.8 earthquake was recorded 103 km E of McCarthy, Alaska at 03:32 UTC on 2026-03-21, 8.2 km deep.

· 8.2 km deep · released about 15 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 1.8 (ml)
Depth
8.2 km below the surface
Felt
no reports yet
Nearest mapped fault
Totschunda fault, 25 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 237 days ago

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

At this magnitude and depth, people at rest would likely notice it out to about 11 km (7 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 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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 4.9 on 2021-05-09 — about 45,000 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.1 109 km E of McCarthy, Alaska · 9 km SE of this epicentre
  2. 5.7 152 km E of McCarthy, Alaska · 50 km E of this epicentre
  3. 5.5 87 km ENE of McCarthy, Alaska · 36 km NNW of this epicentre
  4. 5.4 140 km SSE of Alcan Border, Alaska · 42 km ENE of this epicentre
  5. 5.3 136 km E of McCarthy, Alaska · 36 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 61.3330, -141.0010. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.8 124 km E of McCarthy, Alaska
  2. 1.7 123 km E of McCarthy, Alaska
  3. 1.6 122 km ESE of McCarthy, Alaska
  4. 2.0 106 km E of McCarthy, Alaska
  5. 2.1 107 km E of McCarthy, Alaska
  6. 1.5 130 km E of McCarthy, Alaska
  7. 1.8 129 km ESE of McCarthy, Alaska
  8. 1.9 97 km ESE of McCarthy, Alaska
  9. 1.9 89 km ESE of McCarthy, Alaska
  10. 1.8 90 km ESE of McCarthy, Alaska
  11. 1.8 90 km ESE of McCarthy, Alaska
  12. 1.6 90 km E of McCarthy, Alaska
  13. 1.6 89 km ESE of McCarthy, Alaska
  14. 1.5 81 km ENE of McCarthy, Alaska
  15. 1.5 89 km ESE 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.