QuakeIndex

Earthquake · reviewed by a seismologist

M 4.9mb

128 km WSW of Nikolski, Alaska

· 54 km deep · released about 340 tons of TNT

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 4.9 (mb)
Depth
54 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 279 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 340 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 500× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 22× the energy of this one
  3. Magna, Utah 2020 M 5.7 16× the energy of this one
  4. This earthquake M 4.9 about 340 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 710× 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 52.4081, -170.5441. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.0 168 km SW of Nikolski, Alaska
  2. 2.3 108 km WSW of Nikolski, Alaska
  3. 3.4 164 km WSW of Nikolski, Alaska
  4. 3.5 148 km SW of Nikolski, Alaska
  5. 3.0 150 km SW of Nikolski, Alaska
  6. 2.5 96 km WSW of Nikolski, Alaska
  7. 2.6 171 km SW of Nikolski, Alaska
  8. 5.2 102 km SW of Nikolski, Alaska
  9. 3.1 165 km WSW of Nikolski, Alaska
  10. 2.6 163 km SW of Nikolski, Alaska
  11. 2.2 136 km SW of Nikolski, Alaska
  12. 2.2 134 km SW of Nikolski, Alaska
  13. 4.0 130 km WSW of Nikolski, Alaska
  14. 2.4 118 km SW of Nikolski, Alaska
  15. 4.0 121 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 5.8 on 2019-10-26 — it released about 22 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.