QuakeIndex

Earthquake · reviewed by a seismologist

M 4.7mb

219 km SSE of Old Harbor, Alaska

· 10 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
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 1145 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 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 55.4005, -151.8735. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.6 233 km SSE of Old Harbor, Alaska
  2. 2.4 194 km SSE of Old Harbor, Alaska
  3. 2.5 219 km SSE of Old Harbor, Alaska
  4. 2.4 232 km SSE of Old Harbor, Alaska
  5. 2.5 218 km SSE of Old Harbor, Alaska
  6. 2.4 233 km SSE of Old Harbor, Alaska
  7. 2.2 218 km SSE of Old Harbor, Alaska
  8. 2.6 209 km SSE of Old Harbor, Alaska
  9. 2.2 217 km SE of Akhiok, Alaska
  10. 2.3 201 km SSE of Old Harbor, Alaska
  11. 3.6 211 km SE of Akhiok, Alaska
  12. 2.9 201 km SSE of Old Harbor, Alaska
  13. 2.5 177 km SSE of Old Harbor, Alaska
  14. 2.0 258 km SSE of Akhiok, Alaska
  15. 2.4 209 km SSE of Old Harbor, 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.