QuakeIndex

Earthquake · reviewed by a seismologist

M 4.8mww

232 km SE of Chiniak, Alaska

· 6.8 km deep · released about 240 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 4.8 (mww)
Depth
6.8 km below the surface
Felt
no reports yet
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 1920 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

How big was it?

This earthquake released about 240 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 710× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 32× the energy of this one
  3. Magna, Utah 2020 M 5.7 22× the energy of this one
  4. This earthquake M 4.8 about 240 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 500× 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 56.3292, -149.2714. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.4 262 km SE of Chiniak, Alaska
  2. 2.5 261 km SE of Chiniak, Alaska
  3. 2.8 217 km ESE of Chiniak, Alaska
  4. 2.8 254 km SE of Chiniak, Alaska
  5. 2.8 253 km SE of Chiniak, Alaska
  6. 2.7 246 km SE of Chiniak, Alaska
  7. 3.8 236 km SE of Chiniak, Alaska
  8. 2.3 236 km SE of Chiniak, Alaska
  9. 2.4 260 km SE of Chiniak, Alaska
  10. 2.8 240 km SE of Chiniak, Alaska
  11. 2.6 260 km SE of Chiniak, Alaska
  12. 2.5 259 km SE of Chiniak, Alaska
  13. 3.1 246 km SE of Chiniak, Alaska
  14. 2.9 277 km SE of Chiniak, Alaska
  15. 2.4 266 km SE of Chiniak, 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 7.9 on 2018-01-23 — 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.