QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0ml

203 km SE of Chignik, Alaska

· 8.8 km deep · released about 950 lb 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 3.0 (ml)
Depth
8.8 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1717 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 350,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
  4. This earthquake M 3.0 about 950 lb of TNT

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 54.8943, -156.3358. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.6 244 km SE of Chignik, Alaska
  2. 2.7 206 km SE of Chignik, Alaska
  3. 3.0 239 km SE of Chignik, Alaska
  4. 3.9 south of Alaska
  5. 2.3 216 km SE of Perryville, Alaska
  6. 2.8 201 km SE of Perryville, Alaska
  7. 4.4 209 km SE of Perryville, Alaska
  8. 2.5 170 km SE of Chignik, Alaska
  9. 2.8 208 km SE of Perryville, Alaska
  10. 2.5 204 km SE of Perryville, Alaska
  11. 2.5 212 km SE of Chignik, Alaska
  12. 4.2 223 km SE of Chignik, Alaska
  13. 2.6 187 km SE of Chignik, Alaska
  14. 3.0 190 km SE of Chignik, Alaska
  15. 3.1 202 km SE of Perryville, 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 5.6 on 2021-09-16 — it released about 7,900 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.