QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mb

138 km WNW of Adak, Alaska

· 186 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 (mb)
Depth
186 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 606 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

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 52.3739, -178.4824. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.2 131 km W of Adak, Alaska
  2. 2.0 130 km W of Adak, Alaska
  3. 2.3 153 km WNW of Adak, Alaska
  4. 2.5 155 km WNW of Adak, Alaska
  5. 2.9 133 km W of Adak, Alaska
  6. 2.4 118 km WNW of Adak, Alaska
  7. 2.7 175 km WNW of Adak, Alaska
  8. 2.1 155 km WNW of Adak, Alaska
  9. 2.6 147 km W of Adak, Alaska
  10. 3.8 134 km W of Adak, Alaska
  11. 2.4 127 km WNW of Adak, Alaska
  12. 2.2 110 km W of Adak, Alaska
  13. 2.1 133 km WNW of Adak, Alaska
  14. 1.8 131 km W of Adak, Alaska
  15. 2.5 133 km W of Adak, 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 4.6 on 2024-09-16 — it released about 7.9 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.