QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mb

195 km WNW of Adak, Alaska

· 211 km deep · released about 15 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N
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
211 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2010 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 52.3090, -179.3905. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.0 228 km W of Adak, Alaska
  2. 2.1 159 km W of Adak, Alaska
  3. 3.9 185 km WNW of Adak, Alaska
  4. 3.4 219 km W of Adak, Alaska
  5. 2.8 Andreanof Islands, Aleutian Islands, Alaska
  6. 2.3 196 km W of Adak, Alaska
  7. 2.5 219 km W of Adak, Alaska
  8. 1.8 161 km W of Adak, Alaska
  9. 2.2 201 km W of Adak, Alaska
  10. 3.3 212 km W of Adak, Alaska
  11. 2.5 Andreanof Islands, Aleutian Islands, Alaska
  12. 2.5 200 km W of Adak, Alaska
  13. 4.6 Andreanof Islands, Aleutian Islands, Alaska
  14. 3.2 180 km W of Adak, Alaska
  15. 2.2 222 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 5.7 on 2018-02-08 — it released about 350 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.