QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8ml

129 km ESE of Chignik, Alaska

· 44 km deep · released about 480 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N
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
44 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 312 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 55.9764, -156.3946. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.1 121 km E of Chignik, Alaska
  2. 2.4 111 km E of Chignik, Alaska
  3. 3.1 113 km E of Chignik, Alaska
  4. 2.4 108 km E of Chignik, Alaska
  5. 2.2 116 km E of Chignik, Alaska
  6. 2.1 128 km ESE of Chignik, Alaska
  7. 2.3 136 km ESE of Chignik, Alaska
  8. 1.9 124 km E of Chignik, Alaska
  9. 1.8 141 km ESE of Chignik, Alaska
  10. 1.7 109 km E of Chignik, Alaska
  11. 2.3 160 km ESE of Chignik, Alaska
  12. 1.8 109 km E of Chignik, Alaska
  13. 2.5 142 km ESE of Chignik, Alaska
  14. 2.4 123 km ESE of Chignik, Alaska
  15. 2.5 117 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 6.9 on 2021-10-11 — it released about 1,400,000 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.