QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8ml

184 km SSW of Akhiok, Alaska

· 21 km deep · released about 7.6 tons 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 3.8 (ml)
Depth
21 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 1632 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 7.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 22,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 710× the energy of this one
  4. This earthquake M 3.8 about 7.6 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 16× 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.

Where

Epicentre 55.5225, -155.7063. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.1 south of Alaska
  2. 3.0 168 km SSW of Akhiok, Alaska
  3. 2.5 144 km SSW of Akhiok, Alaska
  4. 3.3 149 km SW of Akhiok, Alaska
  5. 2.6 146 km SSW of Akhiok, Alaska
  6. 3.0 157 km SW of Akhiok, Alaska
  7. 2.4 163 km ESE of Chignik, Alaska
  8. 3.2 152 km SSW of Akhiok, Alaska
  9. 2.5 165 km ESE of Chignik, Alaska
  10. 2.5 155 km SW of Akhiok, Alaska
  11. 4.0 152 km SSW of Akhiok, Alaska
  12. 2.2 south of Alaska
  13. 3.5 157 km SSW of Akhiok, Alaska
  14. 2.3 153 km ESE of Chignik, Alaska
  15. 2.8 191 km SE of Chignik, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.8 on 2021-07-29 — it released about 32 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.