QuakeIndex

Earthquake · reviewed by a seismologist

M 4.7mb

Gulf of Alaska

· 7.0 km deep · released about 170 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 4.7 (mb)
Depth
7.0 km below the surface
Felt
no reports yet
Measured shaking
intensity I (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 975 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 170 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.7 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 1,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 45× the energy of this one
  3. Magna, Utah 2020 M 5.7 32× the energy of this one
  4. This earthquake M 4.7 about 170 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 350× 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 56.8454, -149.3262. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.9 232 km ESE of Chiniak, Alaska
  2. 3.3 221 km SE of Chiniak, Alaska
  3. 2.8 224 km ESE of Chiniak, Alaska
  4. 2.6 217 km SE of Chiniak, Alaska
  5. 3.0 215 km SE of Chiniak, Alaska
  6. 2.9 226 km SE of Chiniak, Alaska
  7. 2.8 240 km ESE of Chiniak, Alaska
  8. 2.7 184 km ESE of Chiniak, Alaska
  9. 2.8 215 km SE of Chiniak, Alaska
  10. 2.6 224 km SE of Chiniak, Alaska
  11. 2.7 242 km ESE of Chiniak, Alaska
  12. 2.8 223 km SE of Chiniak, Alaska
  13. 3.2 237 km ESE of Chiniak, Alaska
  14. 2.8 223 km SE of Chiniak, Alaska
  15. 3.1 184 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 2018-01-23 — it released about 16 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.