QuakeIndex

Earthquake · reviewed by a seismologist

M 5.5mww

256 km ESE of Chiniak, Alaska

· 10 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
10 km below the surface
Felt
1 report · strongest reported intensity II
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 1512 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 1 person has 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 56.5460, -148.5352. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.8 288 km ESE of Chiniak, Alaska
  2. 3.0 243 km SE of Chiniak, Alaska
  3. 3.3 243 km SE of Chiniak, Alaska
  4. 3.4 248 km ESE of Chiniak, Alaska
  5. 3.2 254 km ESE of Chiniak, Alaska
  6. 3.1 253 km SE of Chiniak, Alaska
  7. 3.2 282 km ESE of Chiniak, Alaska
  8. 4.2 283 km ESE of Chiniak, Alaska
  9. 3.2 271 km SE of Chiniak, Alaska
  10. 3.3 253 km SE of Chiniak, Alaska
  11. 3.3 256 km SE of Chiniak, Alaska
  12. 3.9 244 km SE of Chiniak, Alaska
  13. 3.0 239 km ESE of Chiniak, Alaska
  14. 3.2 251 km ESE of Chiniak, Alaska
  15. 3.1 248 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 5.3 on 2018-01-23.

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

On USGS

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