QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8ml

199 km SE of Chignik, Alaska

· 33 km deep · released about 480 lb 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 2.8 (ml)
Depth
33 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1809 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 480 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 32,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 22,000× the energy of this one
  3. Around the size people start to feel M 3.0 2× the energy of this one
  4. This earthquake M 2.8 about 480 lb of TNT

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 55.3274, -155.7320. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.6 177 km SSW of Akhiok, Alaska
  2. 2.8 199 km SE of Chignik, Alaska
  3. 2.9 185 km SSW of Akhiok, Alaska
  4. 1.8 157 km SSW of Akhiok, Alaska
  5. 3.0 169 km ESE of Chignik, Alaska
  6. 2.8 190 km SSW of Akhiok, Alaska
  7. 2.4 170 km SE of Chignik, Alaska
  8. 2.6 158 km SSW of Akhiok, Alaska
  9. 2.6 166 km ESE of Chignik, Alaska
  10. 2.0 154 km ESE of Chignik, Alaska
  11. 2.7 197 km SE of Chignik, Alaska
  12. 2.6 182 km SE of Chignik, Alaska
  13. 2.4 194 km SE of Chignik, Alaska
  14. 2.3 183 km ESE of Chignik, Alaska
  15. 2.2 155 km ESE of Chignik, 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 4.8 on 2021-07-29 — 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.