QuakeIndex

Earthquake · reviewed by a seismologist

M 4.2mb

152 km SE of Akutan, Alaska

· 5.4 km deep · released about 30 tons of TNT

10 km30 km60 km120 km N
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 4.2 (mb)
Depth
5.4 km below the surface
Felt
no reports yet
Measured shaking
intensity I (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1499 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 30 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 5,600× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 250× the energy of this one
  3. Magna, Utah 2020 M 5.7 180× the energy of this one
  4. This earthquake M 4.2 about 30 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 63× 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 53.3456, -163.8940. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.1 147 km SE of Akutan, Alaska
  2. 2.1 121 km SE of Akutan, Alaska
  3. 2.5 Unimak Island region, Alaska
  4. 3.8 151 km S of False Pass, Alaska
  5. 3.2 145 km S of False Pass, Alaska
  6. 2.1 124 km S of False Pass, Alaska
  7. 2.7 175 km S of False Pass, Alaska
  8. 2.6 152 km S of False Pass, Alaska
  9. 2.2 139 km SE of Akutan, Alaska
  10. 2.8 133 km SE of Akutan, Alaska
  11. 2.8 110 km SE of Akutan, Alaska
  12. 2.6 116 km ESE of Akutan, Alaska
  13. 2.6 131 km S of False Pass, Alaska
  14. 2.1 152 km ESE of Akutan, Alaska
  15. 2.7 123 km ESE of Akutan, 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 5.7 on 2020-08-13 — 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.