QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mb

194 km SSE of Atka, Alaska

· 10 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
10 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1143 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 50.6577, -172.8862. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.2 211 km SSE of Atka, Alaska
  2. 2.7 166 km SSE of Atka, Alaska
  3. 2.8 190 km SSE of Atka, Alaska
  4. 2.7 174 km SSE of Atka, Alaska
  5. 3.0 153 km SSE of Atka, Alaska
  6. 2.1 188 km SSE of Atka, Alaska
  7. 2.3 165 km SSE of Atka, Alaska
  8. 2.6 200 km SSE of Atka, Alaska
  9. 2.9 178 km SE of Atka, Alaska
  10. 3.0 226 km SSE of Atka, Alaska
  11. 2.8 Andreanof Islands, Aleutian Islands, Alaska
  12. 2.4 175 km SSE of Atka, Alaska
  13. 2.7 205 km SSE of Atka, Alaska
  14. 2.5 167 km SSE of Atka, Alaska
  15. 3.3 167 km SSE 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 4.2 on 2017-11-29 — it released about 2 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.