QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mw

22 km SE of Circle, Alaska

· 13 km deep · released about 15 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 4.0 (mw)
Depth
13 km below the surface
Felt
5 reports · strongest reported intensity III
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1154 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 5 people have reported feeling it to USGS.

How big was it?

This earthquake released about 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 32× 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 65.6614, -143.7574. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.9 50 km ESE of Central, Alaska
  2. 2.5 28 km ESE of Central, Alaska
  3. 1.6 35 km S of Circle, Alaska
  4. 1.7 13 km E of Circle, Alaska
  5. 1.9 71 km SSE of Circle, Alaska
  6. 2.0 33 km SE of Circle, Alaska
  7. 1.6 33 km ESE of Central, Alaska
  8. 1.7 15 km ESE of Circle, Alaska
  9. 2.0 35 km NE of Circle, Alaska
  10. 1.5 36 km SE of Central, Alaska
  11. 1.8 37 km ESE of Central, Alaska
  12. 2.3 northern Alaska
  13. 1.6 30 km NE of Circle, Alaska
  14. 3.0 34 km NE of Circle, Alaska
  15. 1.5 36 km NE of Circle, 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.