QuakeIndex

Earthquake · reviewed by a seismologist

M 2.6ml

Unimak Island region, Alaska

Yes. A magnitude 2.6 earthquake was recorded in the Unimak Island region, Alaska at 17:38 UTC on 2020-09-29, 34 km deep.

· 34 km deep · released about 240 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 2.6 (ml)
Depth
34 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2169 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 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 240 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 63,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 45,000× the energy of this one
  3. Around the size people start to feel M 3.0 4× the energy of this one
  4. This earthquake M 2.6 about 240 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 5.9 on 2016-10-27 — about 89,000 times the energy of this one.

Before 2016, the USGS record lists 62 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 146 km ESE of Akutan, Alaska · 39 km S of this epicentre
  2. 6.2 Unimak Island region, Alaska · 22 km WSW of this epicentre
  3. 6.2 102 km SSW of False Pass, Alaska · 25 km WNW of this epicentre
  4. 6.2 136 km S of False Pass, Alaska · 27 km SSW of this epicentre
  5. 6.2 115 km ESE of Akutan, Alaska · 28 km W 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 53.8850, -163.6754. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.0 153 km S of False Pass, Alaska
  2. 2.1 102 km S of False Pass, Alaska
  3. 2.5 95 km S of False Pass, AK
  4. 3.0 84 km S of False Pass, Alaska
  5. 2.2 116 km SSW of False Pass, Alaska
  6. 2.0 88 km S of False Pass, Alaska
  7. 2.2 119 km ESE of Akutan, Alaska
  8. 3.0 122 km ESE of Akutan, Alaska
  9. 2.3 116 km ESE of Akutan, Alaska
  10. 2.6 125 km S of False Pass, Alaska
  11. 4.3 121 km ESE of Akutan, AK
  12. 3.5 117 km ESE of Akutan, Alaska
  13. 3.5 121 km ESE of Akutan, Alaska
  14. 2.8 121 km ESE of Akutan, Alaska
  15. 2.3 121 km ESE of Akutan, 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.