QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

216 km WSW of Adak, Alaska

Yes. A magnitude 3.1 earthquake was recorded 216 km WSW of Adak, Alaska at 19:08 UTC on 2023-01-21, 35 km deep.

· 35 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
35 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1324 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 22 km (14 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 6.1 on 2021-09-24 — about 32,000 times the energy of this one.

Before 2016, the USGS record lists 171 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 238 km WSW of Adak, Alaska · 26 km WNW of this epicentre
  2. 7.2 207 km WSW of Adak, Alaska · 30 km N of this epicentre
  3. 6.9 203 km WSW of Adak, Alaska · 30 km N of this epicentre
  4. 6.9 231 km WSW of Adak, Alaska · 34 km NW of this epicentre
  5. 6.8 235 km WSW of Adak, Alaska · 35 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 51.0883, -179.4904. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.2 194 km WSW of Adak, Alaska
  2. 2.1 236 km WSW of Adak, Alaska
  3. 2.2 193 km WSW of Adak, Alaska
  4. 3.1 250 km WSW of Adak, Alaska
  5. 2.7 174 km WSW of Adak, Alaska
  6. 1.9 187 km WSW of Adak, Alaska
  7. 2.6 191 km WSW of Adak, Alaska
  8. 1.8 Andreanof Islands, Aleutian Islands, Alaska
  9. 2.7 204 km WSW of Adak, Alaska
  10. 2.9 241 km WSW of Adak, Alaska
  11. 1.9 178 km WSW of Adak, Alaska
  12. 2.6 178 km WSW of Adak, Alaska
  13. 2.0 218 km WSW of Adak, Alaska
  14. 1.9 191 km WSW of Adak, Alaska
  15. 3.5 244 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.