QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8ml

184 km SE of Chignik, Alaska

· 16 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
16 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1810 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 55.3654, -155.9632. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.9 190 km SSW of Akhiok, Alaska
  2. 3.0 159 km SSW of Akhiok, Alaska
  3. 2.3 180 km SSW of Akhiok, Alaska
  4. 2.5 174 km SE of Chignik, Alaska
  5. 2.4 182 km ESE of Chignik, Alaska
  6. 1.9 167 km SW of Akhiok, Alaska
  7. 3.1 south of Alaska
  8. 2.7 168 km ESE of Chignik, Alaska
  9. 3.2 191 km SE of Chignik, Alaska
  10. 5.6 181 km SE of Chignik, Alaska
  11. 3.9 197 km SE of Chignik, Alaska
  12. 2.3 167 km SW of Akhiok, Alaska
  13. 2.9 167 km SW of Akhiok, Alaska
  14. 3.0 190 km SE of Chignik, Alaska
  15. 1.9 165 km SE 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.