QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9ml

Kodiak Island region, Alaska

Yes. A magnitude 3.9 earthquake was recorded in the Kodiak Island region, Alaska at 23:15 UTC on 2023-11-06, 28 km deep. 1 person has reported feeling it to USGS.

· 28 km deep · released about 11 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Kodiak Island Borough 29 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 3.9 (ml)
Depth
28 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Kodiak Island Borough, 29 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1034 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 85 km (53 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 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 16,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
  3. Magna, Utah 2020 M 5.7 500× the energy of this one
  4. This earthquake M 3.9 about 11 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 22× 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 4.9 on 2021-01-03 — about 32 times the energy of this one.

Before 2016, the USGS record lists 20 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.1 4 km ENE of Karluk, Alaska · 17 km NW of this epicentre
  2. 7.0 26 km SSE of Karluk, Alaska · 19 km SSW of this epicentre
  3. 6.5 24 km SSW of Larsen Bay, Alaska · 15 km S of this epicentre
  4. 6.4 29 km N of Akhiok, Alaska · 32 km S of this epicentre
  5. 6.0 28 km N of Akhiok, Alaska · 32 km S 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 57.4874, -154.1736. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Kodiak Island Borough, AK 29 km (18 mi) NNE earthquakes near Kodiak Island Borough

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

Aftershocks so far

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

  1. 1.5 15 km SW of Karluk, Alaska
  2. 1.7 34 km NW of Akhiok, Alaska
  3. 1.6 19 km SW of Karluk, Alaska
  4. 2.4 25 km SW of Larsen Bay, Alaska
  5. 2.7 3 km SE of Larsen Bay, Alaska
  6. 1.8 24 km NE of Karluk, Alaska
  7. 1.5 13 km S of Karluk, Alaska
  8. 2.1 33 km NNE of Karluk, Alaska
  9. 2.0 12 km WNW of Karluk, Alaska
  10. 1.6 11 km ENE of Karluk, Alaska
  11. 1.7 30 km NNW of Karluk, Alaska
  12. 2.1 24 km NW of Karluk, Alaska
  13. 1.8 14 km WSW of Karluk, Alaska
  14. 2.2 7 km NW of Karluk, Alaska
  15. 1.9 29 km S of Larsen Bay, 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.