QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9mb

193 km E of Atka, Alaska

· 36 km deep · released about 11 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 3.9 (mb)
Depth
36 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2696 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 16,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
  3. Magna, Utah 2020 M 5.7 500× the energy of this one
  4. This earthquake M 3.9 about 11 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 22× 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 51.9103, -171.4232. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.6 169 km WSW of Nikolski, Alaska
  2. 4.2 172 km SW of Nikolski, Alaska
  3. 4.4 177 km SW of Nikolski, Alaska
  4. 2.9 179 km WSW of Nikolski, Alaska
  5. 2.5 192 km ESE of Atka, Alaska
  6. 3.4 183 km WSW of Nikolski, Alaska
  7. 3.0 191 km E of Atka, Alaska
  8. 2.7 186 km E of Atka, Alaska
  9. 3.0 193 km WSW of Nikolski, Alaska
  10. 3.0 194 km ESE of Atka, Alaska
  11. 3.0 209 km SW of Nikolski, Alaska
  12. 3.8 183 km ESE of Atka, Alaska
  13. 3.4 200 km SW of Nikolski, Alaska
  14. 3.6 196 km SW of Nikolski, Alaska
  15. 3.9 214 km SW of Nikolski, 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 5.9 on 2018-08-25 — it released about 1,000 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.