QuakeIndex

Earthquake · reviewed by a seismologist

M 5.0mb

142 km SE of Chignik, Alaska

· 29 km deep · released about 480 tons 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 5.0 (mb)
Depth
29 km below the surface
Felt
no reports yet
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1820 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

How big was it?

This earthquake released about 480 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 350× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 16× the energy of this one
  3. Magna, Utah 2020 M 5.7 11× the energy of this one
  4. This earthquake M 5.0 about 480 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 1,000× 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 55.3622, -156.8545. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.3 143 km SE of Chignik, Alaska
  2. 3.6 161 km SSE of Chignik, Alaska
  3. 2.4 147 km SSE of Chignik, Alaska
  4. 3.0 140 km SE of Chignik, Alaska
  5. 2.7 141 km SSE of Chignik, Alaska
  6. 3.9 137 km SE of Chignik, Alaska
  7. 3.0 153 km SE of Chignik, Alaska
  8. 2.4 118 km SE of Chignik, Alaska
  9. 2.9 139 km SE of Chignik, Alaska
  10. 2.5 137 km SE of Chignik, Alaska
  11. 3.9 135 km SSE of Chignik, Alaska
  12. 2.2 114 km SE of Chignik, Alaska
  13. 2.9 114 km SE of Chignik, Alaska
  14. 2.6 151 km SE of Chignik, Alaska
  15. 2.4 138 km SE of Perryville, 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 22 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.