QuakeIndex

Earthquake · reviewed by a seismologist

M 5.3mww

191 km WSW of Adak, Alaska

· 35 km deep · released about 1.3 kilotons 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 5.3 (mww)
Depth
35 km below the surface
Felt
1 report · strongest reported intensity II
Measured shaking
intensity IV (ShakeMap)
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 606 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 1.3 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 130× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 5.6× the energy of this one
  3. Magna, Utah 2020 M 5.7 4× the energy of this one
  4. This earthquake M 5.3 about 1.3 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 2,800× 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 51.2181, -179.1863. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.6 190 km WSW of Adak, Alaska
  2. 3.6 184 km WSW of Adak, Alaska
  3. 2.2 152 km WSW of Adak, Alaska
  4. 3.1 203 km WSW of Adak, Alaska
  5. 1.8 161 km WSW of Adak, Alaska
  6. 2.2 194 km WSW of Adak, Alaska
  7. 2.2 193 km WSW of Adak, Alaska
  8. 2.6 150 km WSW of Adak, Alaska
  9. 2.7 174 km WSW of Adak, Alaska
  10. 1.9 187 km WSW of Adak, Alaska
  11. 2.6 191 km WSW of Adak, Alaska
  12. 1.8 Andreanof Islands, Aleutian Islands, Alaska
  13. 1.9 197 km WSW of Adak, Alaska
  14. 2.7 204 km WSW of Adak, Alaska
  15. 1.9 178 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 16 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.