QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

152 km SW of Adak, Alaska

Yes. A magnitude 3.1 earthquake was recorded 152 km SW of Adak, Alaska at 10:51 UTC on 2026-09-11, 19 km deep.

· 19 km deep · released about 1,300 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 3.1 (ml)
Depth
19 km below the surface
Felt
no reports yet
Measured shaking
intensity III (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 64 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 37 km (23 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 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 250,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 7,900× the energy of this one
  4. This earthquake M 3.1 about 1,300 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.4× 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 6.5 on 2018-08-15 — about 130,000 times the energy of this one.

Before 2016, the USGS record lists 202 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 162 km WSW of Adak, Alaska · 48 km NW of this epicentre
  2. 7.0 114 km WSW of Adak, Alaska · 46 km NNE of this epicentre
  3. 7.0 148 km WSW of Adak, Alaska · 30 km NNW of this epicentre
  4. 6.9 151 km WSW of Adak, Alaska · 36 km NNW of this epicentre
  5. 6.8 111 km SW of Adak, Alaska · 41 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 51.0870, -178.4380. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.2 150 km SW of Adak, Alaska
  2. 4.2 150 km SW of Adak, Alaska
  3. 4.2 147 km WSW of Adak, Alaska
  4. 2.8 148 km SW of Adak, Alaska
  5. 2.7 159 km SW of Adak, Alaska
  6. 2.2 140 km SW of Adak, Alaska
  7. 2.0 126 km SW of Adak, Alaska
  8. 2.1 126 km WSW of Adak, Alaska
  9. 3.0 127 km WSW of Adak, Alaska
  10. 2.4 125 km WSW of Adak, Alaska
  11. 2.2 125 km WSW of Adak, Alaska
  12. 2.7 150 km SW of Adak, Alaska
  13. 2.5 156 km SW of Adak, Alaska
  14. 2.1 135 km WSW of Adak, Alaska
  15. 3.1 123 km WSW of Adak, 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.