QuakeIndex

Earthquake · reviewed by a seismologist

M 4.9mb

247 km SE of Chignik, Alaska

· 2.7 km deep · released about 340 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 4.9 (mb)
Depth
2.7 km below the surface
Felt
1 report · strongest reported intensity III
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1144 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 340 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 500× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 22× the energy of this one
  3. Magna, Utah 2020 M 5.7 16× the energy of this one
  4. This earthquake M 4.9 about 340 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 710× 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 54.6008, -155.8810. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.5 251 km SE of Chignik, Alaska
  2. 2.4 247 km SE of Chignik, Alaska
  3. 2.5 258 km SE of Chignik, Alaska
  4. 2.6 256 km SE of Chignik, Alaska
  5. 2.8 231 km SE of Chignik, Alaska
  6. 2.5 220 km SE of Chignik, Alaska
  7. 2.4 254 km SE of Chignik, Alaska
  8. 2.6 244 km SE of Chignik, Alaska
  9. 2.7 206 km SE of Chignik, Alaska
  10. 3.0 239 km SE of Chignik, Alaska
  11. 3.9 south of Alaska
  12. 2.8 259 km SE of Chignik, Alaska
  13. 2.5 263 km SE of Chignik, Alaska
  14. 3.3 south of Alaska
  15. 3.2 251 km SE of Chignik, 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.

On USGS

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