QuakeIndex

Earthquake · reviewed by a seismologist

M 4.2mb

37 km WNW of False Pass, Alaska

· 146 km deep · released about 30 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 4.2 (mb)
Depth
146 km below the surface
Felt
1 report · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 793 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 30 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 5,600× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 250× the energy of this one
  3. Magna, Utah 2020 M 5.7 180× the energy of this one
  4. This earthquake M 4.2 about 30 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 63× 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 55.0174, -163.9303. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.8 21 km SSW of False Pass, Alaska
  2. 2.0 51 km W of False Pass, Alaska
  3. 2.9 21 km WSW of False Pass, Alaska
  4. 2.7 28 km WNW of False Pass, Alaska
  5. 1.9 33 km SW of False Pass, Alaska
  6. 2.0 28 km SW of False Pass, Alaska
  7. 2.9 48 km WSW of False Pass, Alaska
  8. 3.0 26 km NNW of False Pass, Alaska
  9. 1.6 30 km WSW of False Pass, Alaska
  10. 2.1 68 km WSW of False Pass, Alaska
  11. 2.3 16 km S of False Pass, Alaska
  12. 2.9 10 km SSW of False Pass, Alaska
  13. 4.3 15 km WNW of False Pass, Alaska
  14. 1.5 42 km SW of False Pass, Alaska
  15. 2.2 4 km N of False Pass, 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.