QuakeIndex

Earthquake · reviewed by a seismologist

M 4.5mb

south of Alaska

· 5.0 km deep · released about 85 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 4.5 (mb)
Depth
5.0 km below the surface
Felt
1 report · strongest reported intensity II
Measured shaking
intensity II (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1421 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 85 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 2,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 89× the energy of this one
  3. Magna, Utah 2020 M 5.7 63× the energy of this one
  4. This earthquake M 4.5 about 85 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 180× 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 55.0609, -155.5416. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.4 209 km SSW of Akhiok, Alaska
  2. 2.7 183 km SSW of Akhiok, Alaska
  3. 2.9 204 km SSW of Akhiok, Alaska
  4. 3.0 256 km SE of Chignik, Alaska
  5. 2.9 199 km SE of Chignik, Alaska
  6. 3.4 208 km SE of Chignik, Alaska
  7. 2.8 215 km SE of Chignik, Alaska
  8. 3.0 178 km SE of Chignik, Alaska
  9. 2.7 186 km ESE of Chignik, Alaska
  10. 2.2 217 km SE of Chignik, Alaska
  11. 4.6 208 km SSW of Akhiok, Alaska
  12. 2.9 190 km SSW of Akhiok, Alaska
  13. 2.9 190 km SE of Chignik, Alaska
  14. 3.5 205 km SE of Chignik, Alaska
  15. 3.3 192 km SSW of Akhiok, 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 4.8 on 2021-07-29 — it released about 2.8 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.