QuakeIndex

Earthquake · reviewed by a seismologist

M 3.3ml

89 km SE of False Pass, Alaska

Yes. A magnitude 3.3 earthquake was recorded 89 km SE of False Pass, Alaska, at 2:52 am AKDT on 26 October 2021 (10:52 UTC), 27 km deep.

· 27 km deep · released about 1.3 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Aleutians East Borough 115 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
Magnitude
M 3.3 (ml)
Depth
27 km below the surface
Felt
no reports yet
Nearest
Aleutians East Borough, 115 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1770 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 44 km (27 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 1.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 130,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 5,600× the energy of this one
  3. Magna, Utah 2020 M 5.7 4,000× the energy of this one
  4. This earthquake M 3.3 about 1.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2.8× more

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 5.0 on 2020-08-20 — about 350 times the energy of this one.

Before 2016, the USGS record lists 26 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.5 47 km SE of False Pass, Alaska · 42 km NW of this epicentre
  2. 6.5 88 km SE of False Pass, Alaska · 8 km SW of this epicentre
  3. 5.8 112 km SE of False Pass, Alaska · 24 km SSE of this epicentre
  4. 5.8 60 km SSW of King Cove, Alaska · 32 km N of this epicentre
  5. 5.7 88 km SE of False Pass, Alaska · 6 km WSW 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 54.2509, -162.5055. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aleutians East Borough, AK 115 km (72 mi) NNE earthquakes near Aleutians East Borough

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

Aftershocks so far

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

  1. 1.9 50 km S of King Cove, Alaska
  2. 2.6 61 km S of King Cove, Alaska
  3. 1.6 41 km SE of False Pass, Alaska
  4. 1.8 91 km S of King Cove, Alaska
  5. 1.5 48 km SSW of King Cove, Alaska
  6. 1.8 82 km SE of False Pass, Alaska
  7. 1.9 96 km SSE of False Pass, Alaska
  8. 2.6 77 km SSE of King Cove, Alaska
  9. 2.6 51 km SSE of King Cove, Alaska
  10. 2.8 116 km SSE of False Pass, Alaska
  11. 1.8 52 km S of King Cove, Alaska
  12. 1.9 Alaska Peninsula
  13. 1.7 55 km SSW of King Cove, Alaska
  14. 2.6 52 km SE of False Pass, Alaska
  15. 2.6 45 km SE of False Pass, 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.