QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

196 km ESE of Atka, Alaska

Yes. A magnitude 3.1 earthquake was recorded 196 km ESE of Atka, Alaska at 12:32 UTC on 2023-02-08, 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 1308 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 5.9 on 2018-08-25 — about 16,000 times the energy of this one.

Before 2016, the USGS record lists 58 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.3 Fox Islands, Aleutian Islands, Alaska · 40 km NW of this epicentre
  2. 7.1 Fox Islands, Aleutian Islands, Alaska · 48 km SE of this epicentre
  3. 6.9 170 km E of Atka, Alaska · 45 km NNW of this epicentre
  4. 6.2 179 km SW of Nikolski, Alaska · 49 km E of this epicentre
  5. 6.1 185 km ESE of Atka, Alaska · 12 km WNW 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 51.8086, -171.4111. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 6.0 169 km SW of Nikolski, Alaska
  2. 3.0 172 km E of Atka, Alaska
  3. 3.6 175 km SW of Nikolski, Alaska
  4. 3.5 181 km ESE of Atka, Alaska
  5. 2.8 188 km E of Atka, Alaska
  6. 3.6 181 km E of Atka, Alaska
  7. 3.6 181 km WSW of Nikolski, Alaska
  8. 3.7 180 km E of Atka, Alaska
  9. 2.6 191 km WSW of Nikolski, Alaska
  10. 2.3 180 km SW of Nikolski, Alaska
  11. 3.1 173 km SW of Nikolski, Alaska
  12. 4.9 189 km E of Atka, Alaska
  13. 3.2 184 km ESE of Atka, Alaska
  14. 2.6 184 km SW of Nikolski, Alaska
  15. 3.4 175 km ESE of Atka, 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.