QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8mb

145 km SW of Adak, Alaska

· 28 km deep · released about 7.6 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 3.8 (mb)
Depth
28 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2493 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 7.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 22,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 710× the energy of this one
  4. This earthquake M 3.8 about 7.6 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 16× 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 51.1383, -178.3593. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.9 149 km WSW of Adak, Alaska
  2. 1.8 146 km WSW of Adak, Alaska
  3. 1.6 153 km WSW of Adak, Alaska
  4. 1.8 154 km WSW of Adak, Alaska
  5. 2.0 110 km SW of Adak, Alaska
  6. 2.9 119 km WSW of Adak, Alaska
  7. 1.8 Andreanof Islands, Aleutian Islands, Alaska
  8. 2.2 136 km SW of Adak, Alaska
  9. 1.8 148 km WSW of Adak, Alaska
  10. 1.7 151 km WSW of Adak, Alaska
  11. 1.9 130 km WSW of Adak, Alaska
  12. 1.9 147 km WSW of Adak, Alaska
  13. 2.1 147 km WSW of Adak, Alaska
  14. 2.1 149 km WSW of Adak, Alaska
  15. 3.7 163 km WSW 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 11,000 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.