QuakeIndex

Earthquake · reviewed by a seismologist

M 5.7mww

118 km SW of Adak, Alaska

Yes. A magnitude 5.7 earthquake was recorded 118 km SW of Adak, Alaska at 16:31 UTC on 2024-12-09, 17 km deep. 3 people have reported feeling it to USGS.

· 17 km deep · released about 5.4 kilotons 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 5.7 (mww)
Depth
17 km below the surface
Felt
3 reports · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 119 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 292 km (181 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 5.4 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.7 would have released about 32 times as much.

  1. Loma Prieta, California 1989 M 6.9 63× the energy of this one
  2. Northridge, California 1994 M 6.7 32× the energy of this one
  3. Mineral, Virginia 2011 M 5.8 1.4× the energy of this one
  4. This earthquake M 5.7 about 5.4 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 11,000× 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 7.9 times the energy of this one.

Before 2016, the USGS record lists 87 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.0 69 km SW of Adak, Alaska · 49 km NNE of this epicentre
  2. 6.8 111 km SW of Adak, Alaska · 37 km NW of this epicentre
  3. 6.8 90 km SSW of Adak, Alaska · 46 km ENE of this epicentre
  4. 6.6 85 km SSW of Adak, Alaska · 49 km ENE of this epicentre
  5. 6.6 117 km SW of Adak, Alaska · 42 km NW 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 51.0055, -177.6184. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.0 99 km SSW of Adak, Alaska
  2. 3.2 94 km SSW of Adak, Alaska
  3. 3.5 110 km SSW of Adak, Alaska
  4. 5.9 96 km SSW of Adak, Alaska
  5. 2.2 115 km SSW of Adak, Alaska
  6. 2.8 116 km SSW of Adak, Alaska
  7. 3.2 129 km SSW of Adak, Alaska
  8. 2.6 129 km SSW of Adak, Alaska
  9. 2.6 147 km SSW of Adak, Alaska
  10. 2.8 121 km SSW of Adak, Alaska
  11. 4.0 117 km SSW of Adak, Alaska
  12. 2.1 114 km SSW of Adak, Alaska
  13. 3.7 115 km SSW of Adak, Alaska
  14. 2.9 136 km SSW of Adak, Alaska
  15. 3.0 114 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.