QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mb

140 km SE of Akutan, Alaska

· 10 km deep · released about 15 tons of TNT

Felt it? Tell USGS Check my area
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 4.0 (mb)
Depth
10 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1154 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 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 32× 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 53.3186, -164.1508. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.4 Unimak Island region, Alaska
  2. 2.1 164 km SE of Akutan, Alaska
  3. 2.5 149 km SE of Akutan, Alaska
  4. 2.3 118 km ESE of Akutan, Alaska
  5. 2.0 115 km ESE of Akutan, Alaska
  6. 3.8 113 km ESE of Akutan, Alaska
  7. 2.1 113 km ESE of Akutan, Alaska
  8. 3.0 116 km ESE of Akutan, Alaska
  9. 2.1 112 km ESE of Akutan, Alaska
  10. 4.7 117 km ESE of Akutan, Alaska
  11. 3.9 123 km ESE of Akutan, Alaska
  12. 2.4 121 km ESE of Akutan, Alaska
  13. 1.9 104 km ESE of Akutan, Alaska
  14. 3.4 109 km ESE of Akutan, Alaska
  15. 2.2 160 km S of False Pass, 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.

On USGS

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