QuakeIndex

Earthquake · reviewed by a seismologist

M 3.6ml

160 km SSW of Akhiok, Alaska

· 20 km deep · released about 3.8 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 3.6 (ml)
Depth
20 km below the surface
Felt
no reports yet
Measured shaking
intensity II (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1607 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 3.8 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 45,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,400× the energy of this one
  4. This earthquake M 3.6 about 3.8 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 7.9× 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 55.6401, -155.2778. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.4 154 km SW of Akhiok, Alaska
  2. 2.7 159 km SSW of Akhiok, Alaska
  3. 2.6 201 km SSW of Akhiok, Alaska
  4. 2.4 146 km SW of Akhiok, Alaska
  5. 2.6 155 km SW of Akhiok, Alaska
  6. 2.9 141 km SW of Akhiok, Alaska
  7. 2.9 178 km SSW of Akhiok, Alaska
  8. 2.6 154 km SSW of Akhiok, Alaska
  9. 2.8 160 km SSW of Akhiok, Alaska
  10. 2.5 south of Alaska
  11. 2.2 133 km SW of Akhiok, Alaska
  12. 3.1 south of Alaska
  13. 3.0 168 km SSW of Akhiok, Alaska
  14. 2.5 144 km SSW of Akhiok, Alaska
  15. 3.3 149 km SW of Akhiok, 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 63 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.