QuakeIndex

Earthquake · reviewed by a seismologist

M 4.9mb

111 km NNW of Nikolski, Alaska

· 215 km deep · released about 340 tons 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 4.9 (mb)
Depth
215 km below the surface
Felt
2 reports · strongest reported intensity IV
Measured shaking
intensity II (ShakeMap)
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 1220 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 2 people have reported feeling it to USGS.

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 53.7903, -169.7512. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.0 99 km NW of Nikolski, Alaska
  2. 3.1 97 km NW of Nikolski, Alaska
  3. 1.6 69 km NNW of Nikolski, Alaska
  4. 2.2 81 km NNW of Nikolski, Alaska
  5. 4.0 76 km NNW of Nikolski, Alaska
  6. 4.2 142 km NNW of Nikolski, Alaska
  7. 2.0 100 km NW of Nikolski, Alaska
  8. 2.1 116 km NW of Nikolski, Alaska
  9. 2.7 69 km NNW of Nikolski, Alaska
  10. 2.3 115 km NW of Nikolski, Alaska
  11. 2.9 73 km NW of Nikolski, Alaska
  12. 3.6 84 km NW 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 5.0 on 2020-01-13 — it released about 1.4 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.