QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4ml

28 km E of Slana, Alaska

Yes. A magnitude 3.4 earthquake was recorded 28 km E of Slana, Alaska, at 2:21 pm AKST on 28 December 2021 (23:21 UTC), 4.4 km deep.

· 4.4 km deep · released about 1.9 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Copper River Census Area 75 km
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 3.4 (ml)
Depth
4.4 km below the surface
Felt
no reports yet
Nearest
Copper River Census Area, 75 km SSW
Nearest mapped fault
Totschunda fault, 10 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 1713 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 57 km (35 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 1.9 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 89,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,800× the energy of this one
  4. This earthquake M 3.4 about 1.9 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 4× 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 4.1 on 2021-07-26 — about 11 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

  1. 5.1 3 km ENE of Mentasta Lake, Alaska · 33 km NNW of this epicentre
  2. 5.1 17 km ESE of Mentasta Lake, Alaska · 21 km N of this epicentre
  3. 5.0 16 km WNW of Mentasta Lake, Alaska · 49 km NW of this epicentre
  4. 5.0 21 km N of Nabesna, Alaska · 26 km ESE 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 62.6689, -143.4024. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Copper River Census Area, AK 75 km (47 mi) SSW earthquakes near Copper River Census Area

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

  1. 1.5 31 km SW of Tetlin, Alaska
  2. 1.6 7 km NE of Slana, Alaska
  3. 3.0 13 km ENE of Slana, Alaska
  4. 2.3 13 km SE of Mentasta Lake, Alaska
  5. 3.1 13 km N of Mentasta Lake, Alaska
  6. 1.5 14 km SE of Mentasta Lake, Alaska
  7. 2.0 29 km SW of Tetlin, Alaska
  8. 1.7 13 km E of Slana, Alaska
  9. 2.1 29 km SW of Tetlin, Alaska
  10. 1.8 26 km E of Slana, Alaska
  11. 1.8 24 km SE of Mentasta Lake, Alaska
  12. 1.6 27 km E of Slana, Alaska
  13. 2.0 27 km NNW of Nabesna, Alaska
  14. 1.8 7 km SE of Mentasta Lake, Alaska
  15. 1.6 5 km ESE of Mentasta Lake, 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.