QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8ml

149 km SSE of Chignik, Alaska

· 12 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
12 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1769 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 55.1787, -157.0936. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.4 158 km SSE of Chignik, Alaska
  2. 2.5 186 km SE of Perryville, Alaska
  3. 4.5 147 km SE of Perryville, Alaska
  4. 2.7 142 km SE of Perryville, Alaska
  5. 3.2 142 km SE of Perryville, Alaska
  6. 2.3 156 km SSE of Chignik, Alaska
  7. 2.7 140 km SE of Chignik, Alaska
  8. 2.6 150 km SE of Chignik, Alaska
  9. 2.5 170 km SE of Chignik, Alaska
  10. 2.4 102 km SE of Chignik, Alaska
  11. 3.3 137 km SE of Perryville, Alaska
  12. 2.3 122 km SE of Chignik, Alaska
  13. 2.5 146 km SE of Perryville, Alaska
  14. 2.4 Alaska Peninsula
  15. 2.8 145 km SSE 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 5.9 on 2021-07-29 — it released about 45,000 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.