QuakeIndex

Earthquake · reviewed by a seismologist

M 4.6ml

114 km E of Chignik, Alaska

· 45 km deep · released about 120 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 4.6 (ml)
Depth
45 km below the surface
Felt
2 reports · strongest reported intensity III
Measured shaking
intensity IV (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 290 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 2 people have reported feeling it to USGS.

How big was it?

This earthquake released about 120 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 1,400× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 63× the energy of this one
  3. Magna, Utah 2020 M 5.7 45× the energy of this one
  4. This earthquake M 4.6 about 120 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 250× 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 56.3540, -156.5619. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.9 115 km E of Chignik, Alaska
  2. 2.1 108 km ENE of Chignik, Alaska
  3. 1.7 82 km E of Chignik, Alaska
  4. 1.8 82 km E of Chignik, Alaska
  5. 1.9 97 km ESE of Chignik, Alaska
  6. 2.0 106 km ESE of Chignik, Alaska
  7. 1.9 102 km E of Chignik, Alaska
  8. 2.6 116 km E of Chignik, Alaska
  9. 2.2 131 km E of Chignik, Alaska
  10. 2.3 128 km E of Chignik, Alaska
  11. 2.8 92 km ENE of Chignik, Alaska
  12. 2.4 114 km E of Chignik, Alaska
  13. 2.3 114 km E of Chignik, Alaska
  14. 2.4 127 km ESE of Chignik, Alaska
  15. 3.2 129 km SSE of Ugashik, 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 6.9 on 2021-10-11 — it released about 2,800 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.