QuakeIndex

Earthquake · reviewed by a seismologist

M 4.6mb

181 km WSW of Adak, Alaska

· 35 km deep · released about 120 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 4.6 (mb)
Depth
35 km below the surface
Felt
no reports yet
Measured shaking
intensity IV (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 100 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

How big was it?

This earthquake released about 120 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 1,400× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 63× the energy of this one
  3. Magna, Utah 2020 M 5.7 45× the energy of this one
  4. This earthquake M 4.6 about 120 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 250× 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 51.1458, -178.9713. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.5 155 km WSW of Adak, Alaska
  2. 3.1 184 km WSW of Adak, Alaska
  3. 2.4 176 km WSW of Adak, Alaska
  4. 2.4 179 km WSW of Adak, Alaska
  5. 2.4 164 km SW of Adak, Alaska
  6. 2.2 147 km WSW of Adak, Alaska
  7. 2.7 205 km WSW of Adak, Alaska
  8. 2.5 203 km WSW of Adak, Alaska
  9. 2.6 154 km WSW of Adak, Alaska
  10. 2.3 170 km WSW of Adak, Alaska
  11. 2.3 157 km SW of Adak, Alaska
  12. 2.2 193 km WSW of Adak, Alaska
  13. 2.3 193 km WSW of Adak, Alaska
  14. 2.3 147 km WSW of Adak, Alaska
  15. 4.9 204 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.

For this area

The largest earthquake within 50 km in our catalogue was M 6.1 on 2021-09-24 — it released about 180 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.