QuakeIndex

Earthquake · reviewed by a seismologist

M 4.1mb

181 km E of Atka, Alaska

· 58 km deep · released about 21 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 4.1 (mb)
Depth
58 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 513 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 52.1317, -171.5547. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.5 176 km E of Atka, Alaska
  2. 2.8 176 km E of Atka, Alaska
  3. 3.9 170 km E of Atka, Alaska
  4. 4.4 171 km E of Atka, Alaska
  5. 3.0 173 km E of Atka, Alaska
  6. 4.4 167 km E of Atka, Alaska
  7. 3.5 178 km E of Atka, Alaska
  8. 5.6 172 km ENE of Atka, Alaska
  9. 3.2 174 km ENE of Atka, Alaska
  10. 4.9 168 km E of Atka, Alaska
  11. 3.4 182 km E of Atka, Alaska
  12. 3.3 181 km E of Atka, Alaska
  13. 3.6 182 km WSW of Nikolski, Alaska
  14. 2.9 168 km WSW of Nikolski, Alaska
  15. 3.5 182 km WSW of Nikolski, 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 5.9 on 2018-08-25 — it released about 500 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.