QuakeIndex

Earthquake · reviewed by a seismologist

M 5.7mww

155 km SSW of Akhiok, Alaska

· 13 km deep · released about 5.4 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 5.7 (mww)
Depth
13 km below the surface
Felt
3 reports · strongest reported intensity II
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
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 226 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 3 people have reported feeling it to USGS.

How big was it?

This earthquake released about 5.4 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.7 would have released about 32 times as much.

  1. Loma Prieta, California 1989 M 6.9 63× the energy of this one
  2. Northridge, California 1994 M 6.7 32× the energy of this one
  3. Mineral, Virginia 2011 M 5.8 1.4× the energy of this one
  4. This earthquake M 5.7 about 5.4 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 11,000× 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 55.6151, -154.9176. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.4 116 km S of Akhiok, Alaska
  2. 2.4 120 km S of Akhiok, Alaska
  3. 2.3 188 km S of Akhiok, Alaska
  4. 2.6 196 km SSW of Akhiok, Alaska
  5. 2.6 156 km SSW of Akhiok, Alaska
  6. 2.9 155 km SSW of Akhiok, Alaska
  7. 3.1 116 km S of Akhiok, Alaska
  8. 2.3 172 km SSW of Akhiok, Alaska
  9. 2.7 186 km S of Akhiok, Alaska
  10. 2.3 113 km SSW 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 4.7 on 2021-07-29.

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

On USGS

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