QuakeIndex

Earthquake · reviewed by a seismologist

M 2.0ml

102 km SSW of False Pass, Alaska

Yes. A magnitude 2.0 earthquake was recorded 102 km SSW of False Pass, Alaska, at 2:01 am AKDT on 21 October 2021 (10:01 UTC), 20 km deep.

· 20 km deep · released about 30 lb of TNT

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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 2.0 (ml)
Depth
20 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1803 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. 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 30 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 350,000× the energy of this one
  3. Around the size people start to feel M 3.0 32× the energy of this one
  4. This earthquake M 2.0 about 30 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 5.1 on 2021-01-11 — about 45,000 times the energy of this one.

Before 2016, the USGS record lists 38 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.5 81 km ESE of Akutan, Alaska · 49 km WSW of this epicentre
  2. 6.5 79 km SW of False Pass, Alaska · 33 km NNW of this epicentre
  3. 6.4 85 km ESE of Akutan, Alaska · 50 km WSW of this epicentre
  4. 6.2 Unimak Island region, Alaska · 25 km S of this epicentre
  5. 6.2 102 km SSW of False Pass, Alaska · 1 km E 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 54.0002, -164.0098. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.6 117 km ESE of Akutan, Alaska
  2. 3.3 117 km ESE of Akutan, Alaska
  3. 2.0 112 km ESE of Akutan, Alaska
  4. 3.3 119 km ESE of Akutan, Alaska
  5. 4.5 122 km ESE of Akutan, Alaska
  6. 2.3 116 km ESE of Akutan, Alaska
  7. 4.8 120 km ESE of Akutan, Alaska
  8. 1.8 84 km SW of False Pass, Alaska
  9. 3.7 101 km S of False Pass, Alaska
  10. 2.7 78 km SSW of False Pass, Alaska
  11. 1.7 110 km SSW of False Pass, Alaska
  12. 1.8 116 km ESE of Akutan, Alaska
  13. 2.0 107 km SSW of False Pass, Alaska
  14. 2.0 92 km ESE of Akutan, Alaska
  15. 2.2 94 km S 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.