QuakeIndex

Earthquake · reviewed by a seismologist

M 5.9mww

Andreanof Islands, Aleutian Islands, Alaska

· 30 km deep · released about 11 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 5.9 (mww)
Depth
30 km below the surface
Felt
4 reports · strongest reported intensity V
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 279 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 4 people have reported feeling it to USGS.

How big was it?

This earthquake released about 11 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.9 would have released about 32 times as much.

  1. Ridgecrest, California 2019 M 7.1 63× the energy of this one
  2. Loma Prieta, California 1989 M 6.9 32× the energy of this one
  3. Northridge, California 1994 M 6.7 16× the energy of this one
  4. This earthquake M 5.9 about 11 kilotons of TNT
  5. Mineral, Virginia 2011 M 5.8 this one released 1.4× more
  6. Magna, Utah 2020 M 5.7 this one released 2× 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 51.3349, -178.1181. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.0 92 km SW of Adak, Alaska
  2. 2.0 85 km WSW of Adak, Alaska
  3. 2.2 123 km SW of Adak, Alaska
  4. 2.8 Andreanof Islands, Aleutian Islands, Alaska
  5. 2.7 134 km SW of Adak, Alaska
  6. 1.9 81 km WSW of Adak, Alaska
  7. 2.9 139 km SW of Adak, Alaska
  8. 2.7 157 km SW of Adak, Alaska
  9. 2.9 137 km WSW of Adak, Alaska
  10. 1.9 116 km WSW of Adak, Alaska
  11. 2.1 111 km WSW of Adak, Alaska
  12. 1.5 121 km SW of Adak, Alaska
  13. 2.1 131 km SW of Adak, Alaska
  14. 1.8 130 km SW of Adak, Alaska
  15. 2.1 119 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 7.9 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.