QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

133 km SSW of Adak, Alaska

Yes. A magnitude 3.1 earthquake was recorded 133 km SSW of Adak, Alaska at 08:49 UTC on 2024-12-09, 10 km deep.

· 10 km deep · released about 1,300 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 3.1 (ml)
Depth
10 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 634 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 41 km (25 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 6.3 on 2024-12-09 — about 63,000 times the energy of this one.

Before 2016, the USGS record lists 31 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.8 90 km SSW of Adak, Alaska · 47 km NE of this epicentre
  2. 6.4 146 km S of Adak, Alaska · 48 km ESE of this epicentre
  3. 6.0 130 km SSW of Adak, Alaska · 5 km NNW of this epicentre
  4. 6.0 161 km SSW of Adak, Alaska · 28 km SSW of this epicentre
  5. 6.0 136 km S of Adak, Alaska · 36 km ESE 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 50.7806, -177.4271. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.6 129 km SSW of Adak, Alaska
  2. 2.1 115 km SSW of Adak, Alaska
  3. 2.0 109 km SSW of Adak, Alaska
  4. 2.2 115 km SSW of Adak, Alaska
  5. 3.2 124 km SSW of Adak, Alaska
  6. 2.1 111 km SSW of Adak, Alaska
  7. 3.4 120 km SSW of Adak, Alaska
  8. 2.1 107 km SSW of Adak, Alaska
  9. 2.1 114 km SSW of Adak, Alaska
  10. 2.2 127 km SSW of Adak, Alaska
  11. 3.7 124 km SSW of Adak, Alaska
  12. 2.1 109 km SSW of Adak, Alaska
  13. 2.0 88 km SSW of Adak, Alaska
  14. 3.4 140 km SSW of Adak, Alaska
  15. 2.8 118 km SSW 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.