QuakeIndex

Earthquake · reviewed by a seismologist

M 4.1mb

147 km WSW of Adak, Alaska

· 30 km deep · released about 21 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 4.1 (mb)
Depth
30 km below the surface
Felt
no reports yet
Measured shaking
intensity IV (ShakeMap)
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 89 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 21 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 7,900× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 350× the energy of this one
  3. Magna, Utah 2020 M 5.7 250× the energy of this one
  4. This earthquake M 4.1 about 21 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 45× 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 51.1620, -178.4274. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.7 138 km SW of Adak, Alaska
  2. 2.6 167 km SW of Adak, Alaska
  3. 2.6 167 km SW of Adak, Alaska
  4. 2.5 132 km WSW of Adak, Alaska
  5. 2.8 111 km SW of Adak, Alaska
  6. 2.4 117 km WSW of Adak, Alaska
  7. 4.6 181 km WSW of Adak, Alaska
  8. 2.5 121 km WSW of Adak, Alaska
  9. 3.0 124 km WSW of Adak, Alaska
  10. 2.5 122 km SW of Adak, Alaska
  11. 2.5 149 km SW of Adak, Alaska
  12. 2.3 125 km WSW of Adak, Alaska
  13. 2.8 111 km WSW of Adak, Alaska
  14. 2.2 121 km WSW of Adak, Alaska
  15. 2.4 131 km SW 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 6.5 on 2018-08-15 — it released about 4,000 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.