QuakeIndex

Earthquake · reviewed by a seismologist

M 5.0mww

199 km SE of Perryville, Alaska

· 20 km deep · released about 480 tons 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 5.0 (mww)
Depth
20 km below the surface
Felt
33 reports · strongest reported intensity V
Measured shaking
intensity II (ShakeMap)
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 640 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 33 people have reported feeling it to USGS.

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 54.6782, -156.8589. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.1 195 km SE of Perryville, Alaska
  2. 2.9 185 km SE of Perryville, Alaska
  3. 2.4 152 km SE of Perryville, Alaska
  4. 2.8 213 km SE of Perryville, Alaska
  5. 2.7 195 km SE of Chignik, Alaska
  6. 2.4 180 km SE of Perryville, Alaska
  7. 2.6 175 km SE of Perryville, Alaska
  8. 3.1 197 km SE of Perryville, Alaska
  9. 2.7 193 km SE of Chignik, Alaska
  10. 2.7 south of Alaska
  11. 3.4 194 km SE of Chignik, Alaska
  12. 4.7 south of Alaska
  13. 2.5 197 km SE of Perryville, Alaska
  14. 3.0 south of Alaska
  15. 2.9 167 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 5.6 on 2021-09-16 — 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.