QuakeIndex

Earthquake · reviewed by a seismologist

M 4.8mb

236 km SSW of Adak, Alaska

· 27 km deep · released about 240 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 4.8 (mb)
Depth
27 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1139 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 240 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 710× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 32× the energy of this one
  3. Magna, Utah 2020 M 5.7 22× the energy of this one
  4. This earthquake M 4.8 about 240 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 500× 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 50.0079, -178.2526. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.2 207 km SSW of Adak, Alaska
  2. 3.5 268 km SSW of Adak, Alaska
  3. 2.1 Andreanof Islands, Aleutian Islands, Alaska
  4. 3.3 255 km SSW of Adak, Alaska
  5. 2.1 196 km SSW of Adak, Alaska
  6. 3.7 Andreanof Islands, Aleutian Islands, Alaska
  7. 2.9 225 km SW of Adak, Alaska
  8. 3.2 276 km SSW of Adak, Alaska
  9. 4.5 259 km SSW of Adak, Alaska
  10. 2.9 246 km SSW of Adak, Alaska
  11. 2.4 215 km SSW of Adak, Alaska
  12. 3.4 200 km SSW of Adak, Alaska
  13. 2.0 260 km SSW of Adak, Alaska
  14. 2.2 257 km SSW of Adak, Alaska
  15. 2.7 255 km SSW 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 4.2 on 2016-07-24.

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

On USGS

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