QuakeIndex

Earthquake · reviewed by a seismologist

M 4.2ml

109 km SE of Perryville, Alaska

· 29 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 (ml)
Depth
29 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2017 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 55.2222, -157.8975. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.2 Alaska Peninsula
  2. 3.8 122 km SSE of Perryville, Alaska
  3. 2.8 157 km SE of Perryville, Alaska
  4. 3.0 119 km SSE of Perryville, Alaska
  5. 4.5 154 km SE of Perryville, Alaska
  6. 3.2 106 km SSE of Perryville, Alaska
  7. 3.4 116 km SSE of Perryville, Alaska
  8. 3.2 94 km SSE of Perryville, Alaska
  9. 3.7 113 km SSE of Perryville, Alaska
  10. 2.5 62 km SE of Perryville, Alaska
  11. 4.8 135 km SE of Perryville, Alaska
  12. 4.5 142 km SE of Perryville, Alaska
  13. 4.5 136 km SE of Perryville, Alaska
  14. 4.2 91 km SSE of Chignik, Alaska
  15. 3.9 118 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.

For this area

The largest earthquake within 50 km in our catalogue was M 5.7 on 2016-05-31 — 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.