QuakeIndex

Earthquake · reviewed by a seismologist

M 4.9mb

143 km SE of Nikolski, Alaska

Yes. A magnitude 4.9 earthquake was recorded 143 km SE of Nikolski, Alaska at 02:58 UTC on 2017-12-10, 24 km deep.

· 24 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
24 km below the surface
Felt
no reports yet
Nearest mapped fault
Alaska-Aleutian subduction zone, 16 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1192 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 180 km (112 mi) from the epicentre. Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

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.

For this area

The largest earthquake within 50 km since 2016 was M 5.9 on 2017-05-24 — about 32 times the energy of this one.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.0 Fox Islands, Aleutian Islands, Alaska · 31 km NW of this epicentre
  2. 6.7 103 km SE of Nikolski, Alaska · 40 km NW of this epicentre
  3. 6.4 123 km ESE of Nikolski, Alaska · 49 km N of this epicentre
  4. 6.3 110 km SE of Nikolski, Alaska · 33 km NW of this epicentre
  5. 6.3 119 km ESE of Nikolski, Alaska · 48 km N of this epicentre

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 52.1647, -167.1701. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.9 152 km ESE of Nikolski, Alaska
  2. 2.9 146 km ESE of Nikolski, Alaska
  3. 3.1 145 km ESE of Nikolski, Alaska
  4. 2.3 134 km ESE of Nikolski, Alaska
  5. 2.7 153 km ESE of Nikolski, Alaska
  6. 2.4 148 km ESE of Nikolski, Alaska
  7. 4.0 135 km ESE of Nikolski, Alaska
  8. 3.1 149 km ESE of Nikolski, Alaska
  9. 4.0 154 km ESE of Nikolski, Alaska
  10. 3.5 151 km ESE of Nikolski, Alaska
  11. 5.3 139 km ESE of Nikolski, Alaska
  12. 2.9 142 km ESE of Nikolski, Alaska
  13. 2.2 127 km ESE of Nikolski, Alaska
  14. 2.9 170 km SE of Nikolski, Alaska
  15. 3.6 179 km SE 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.

On USGS

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