QuakeIndex

Earthquake · reviewed by a seismologist

M 5.5mww

276 km ESE of Chiniak, Alaska

· 6.0 km deep · released about 2.7 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 5.5 (mww)
Depth
6.0 km below the surface
Felt
2 reports · strongest reported intensity II
Measured shaking
intensity II (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 1140 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 2 people have reported feeling it to USGS.

How big was it?

This earthquake released about 2.7 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 63× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2.8× the energy of this one
  3. Magna, Utah 2020 M 5.7 2× the energy of this one
  4. This earthquake M 5.5 about 2.7 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 5,600× 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 56.2956, -148.4314. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.5 261 km ESE of Chiniak, Alaska
  2. 2.8 251 km ESE of Chiniak, Alaska
  3. 3.0 254 km ESE of Chiniak, Alaska
  4. 3.0 260 km ESE of Chiniak, Alaska
  5. 2.8 251 km ESE of Chiniak, Alaska
  6. 2.8 266 km ESE of Chiniak, Alaska
  7. 3.0 257 km ESE of Chiniak, Alaska
  8. 2.6 254 km SE of Chiniak, Alaska
  9. 3.8 284 km SE of Chiniak, Alaska
  10. 2.6 267 km SE of Chiniak, Alaska
  11. 2.6 267 km SE of Chiniak, Alaska
  12. 2.2 260 km ESE of Chiniak, Alaska
  13. 2.2 262 km ESE of Chiniak, Alaska
  14. 2.8 255 km SE of Chiniak, Alaska
  15. 2.4 256 km ESE 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 5.5 on 2018-01-24.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.