QuakeIndex

Earthquake · reviewed by a seismologist

M 5.8mww

229 km WSW of Adak, Alaska

· 25 km deep · released about 7.6 kilotons 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 5.8 (mww)
Depth
25 km below the surface
Felt
no reports yet
Measured shaking
intensity V (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 280 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

How big was it?

This earthquake released about 7.6 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.8 would have released about 32 times as much.

  1. Ridgecrest, California 2019 M 7.1 89× the energy of this one
  2. Loma Prieta, California 1989 M 6.9 45× the energy of this one
  3. Northridge, California 1994 M 6.7 22× the energy of this one
  4. This earthquake M 5.8 about 7.6 kilotons of TNT
  5. Magna, Utah 2020 M 5.7 this one released 1.4× more
  6. Around the size people start to feel M 3.0 this one released 16,000× 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 51.1664, -179.7462. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.6 251 km WSW of Adak, Alaska
  2. 2.0 240 km WSW of Adak, Alaska
  3. 2.2 251 km WSW of Adak, Alaska
  4. 3.3 237 km WSW of Adak, Alaska
  5. 5.4 247 km WSW of Adak, Alaska
  6. 2.2 255 km WSW of Adak, Alaska
  7. 2.2 247 km WSW of Adak, Alaska
  8. 2.4 249 km WSW of Adak, Alaska
  9. 3.8 248 km WSW of Adak, Alaska
  10. 4.0 245 km WSW of Adak, Alaska
  11. 2.9 242 km WSW of Adak, Alaska
  12. 2.4 235 km WSW of Adak, Alaska
  13. 5.1 239 km WSW of Adak, Alaska
  14. 2.8 242 km WSW of Adak, Alaska
  15. 2.6 241 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 6.1 on 2020-01-26 — it released about 2.8 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.