QuakeIndex

Earthquake · reviewed by a seismologist

M 4.1mb

142 km ESE of Atka, Alaska

· 35 km deep · released about 21 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 4.1 (mb)
Depth
35 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1653 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 21 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 7,900× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 350× the energy of this one
  3. Magna, Utah 2020 M 5.7 250× the energy of this one
  4. This earthquake M 4.1 about 21 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 45× 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 51.9430, -172.1705. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.2 174 km E of Atka, Alaska
  2. 4.1 155 km ESE of Atka, Alaska
  3. 2.6 165 km E of Atka, Alaska
  4. 3.0 179 km ESE of Atka, Alaska
  5. 3.0 162 km E of Atka, Alaska
  6. 3.3 139 km E of Atka, Alaska
  7. 3.0 140 km ESE of Atka, Alaska
  8. 3.3 133 km ESE of Atka, Alaska
  9. 5.0 129 km E of Atka, Alaska
  10. 3.5 174 km ESE of Atka, Alaska
  11. 3.6 164 km E of Atka, Alaska
  12. 2.6 153 km E of Atka, Alaska
  13. 3.1 155 km ESE of Atka, Alaska
  14. 2.3 162 km ESE of Atka, Alaska
  15. 3.0 177 km ESE of Atka, 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 4.6 on 2021-06-30 — it released about 5.6 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.