QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9ml

147 km S of Akhiok, Alaska

· 5.1 km deep · released about 11 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 3.9 (ml)
Depth
5.1 km below the surface
Felt
no reports yet
Measured shaking
intensity I (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 703 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 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 16,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
  3. Magna, Utah 2020 M 5.7 500× the energy of this one
  4. This earthquake M 3.9 about 11 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 22× 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 55.6294, -153.9375. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.8 163 km S of Akhiok, Alaska
  2. 2.2 127 km S of Akhiok, Alaska
  3. 2.5 130 km SSE of Akhiok, Alaska
  4. 2.6 103 km SSE of Akhiok, Alaska
  5. 2.7 141 km S of Akhiok, Alaska
  6. 2.5 113 km S of Akhiok, Alaska
  7. 3.2 155 km S of Akhiok, Alaska
  8. 3.3 142 km S of Akhiok, Alaska
  9. 3.2 152 km S of Akhiok, Alaska
  10. 2.5 128 km SSE of Akhiok, Alaska
  11. 5.0 111 km S of Akhiok, Alaska
  12. 3.6 112 km S of Akhiok, Alaska
  13. 3.8 116 km S of Akhiok, Alaska
  14. 4.9 117 km S of Akhiok, Alaska
  15. 5.2 110 km S 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 5.1 on 2020-07-08 — it released about 63 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.