QuakeIndex

Earthquake · reviewed by a seismologist

M 5.9mww

163 km ESE of Nikolski, Alaska

· 10 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
10 km below the surface
Felt
1 report · strongest reported intensity II
Measured shaking
intensity IV (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 1146 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 1 person has 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 52.3220, -166.6659. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.5 148 km ESE of Nikolski, Alaska
  2. 2.4 149 km ESE of Nikolski, Alaska
  3. 2.1 137 km S of Unalaska, Alaska
  4. 2.1 130 km S of Unalaska, Alaska
  5. 2.1 150 km ESE of Nikolski, Alaska
  6. 2.4 146 km SE of Nikolski, Alaska
  7. 4.9 143 km SE of Nikolski, Alaska
  8. 2.1 137 km S of Unalaska, Alaska
  9. 2.2 132 km S of Unalaska, Alaska
  10. 2.4 169 km SE of Nikolski, Alaska
  11. 2.0 170 km ESE of Nikolski, Alaska
  12. 1.5 126 km S of Unalaska, Alaska
  13. 2.0 134 km ESE of Nikolski, Alaska
  14. 2.3 124 km S of Unalaska, Alaska
  15. 2.1 146 km S of Unalaska, 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 5.3 on 2017-05-24.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.