QuakeIndex

Earthquake · reviewed by a seismologist

M 5.3mwr

155 km SE of Chignik, Alaska

· 36 km deep · released about 1.3 kilotons 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 5.3 (mwr)
Depth
36 km below the surface
Felt
no reports yet
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1241 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 1.3 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 130× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 5.6× the energy of this one
  3. Magna, Utah 2020 M 5.7 4× the energy of this one
  4. This earthquake M 5.3 about 1.3 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 2,800× 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 55.1678, -156.9458. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.7 146 km SE of Perryville, Alaska
  2. 3.2 144 km SE of Perryville, Alaska
  3. 2.3 164 km SSE of Chignik, Alaska
  4. 2.0 143 km SE of Perryville, Alaska
  5. 2.5 147 km SE of Chignik, Alaska
  6. 2.5 south of Alaska
  7. 2.5 167 km SE of Chignik, Alaska
  8. 3.0 147 km SSE of Chignik, Alaska
  9. 2.3 Alaska Peninsula
  10. 3.2 158 km SE of Chignik, Alaska
  11. 3.5 156 km SSE of Chignik, Alaska
  12. 4.1 131 km SE of Chignik, Alaska
  13. 4.4 166 km SE of Chignik, Alaska
  14. 2.4 151 km SE of Perryville, Alaska
  15. 2.5 147 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 7.9 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.