QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mb

south of Alaska

· 12 km deep · released about 15 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 4.0 (mb)
Depth
12 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1144 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 54.4622, -156.7616. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.8 185 km SE of Perryville, Alaska
  2. 3.3 197 km SE of Perryville, Alaska
  3. 3.4 204 km SE of Perryville, Alaska
  4. 3.8 198 km SE of Perryville, Alaska
  5. 2.9 202 km SE of Perryville, Alaska
  6. 3.4 187 km SE of Perryville, Alaska
  7. 3.5 199 km SE of Chignik, Alaska
  8. 2.1 196 km SE of Perryville, Alaska
  9. 4.1 259 km SE of Perryville, Alaska
  10. 2.8 206 km SE of Perryville, Alaska
  11. 3.3 209 km SE of Perryville, Alaska
  12. 2.9 210 km SE of Perryville, Alaska
  13. 2.8 201 km SE of Perryville, Alaska
  14. 3.2 194 km SE of Perryville, Alaska
  15. 2.8 217 km SE of Perryville, 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.