QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

Kodiak Island region, Alaska

Yes. A magnitude 1.5 earthquake was recorded in the Kodiak Island region, Alaska, at 5:22 pm AKDT on 7 October 2021 (01:22 UTC), 4.7 km deep.

· 4.7 km deep · released about 5.4 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Kodiak Island Borough 87 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 1.5 (ml)
Depth
4.7 km below the surface
Felt
no reports yet
Nearest
Kodiak Island Borough, 87 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1803 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 9 km (6 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 5.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 lb of TNT

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 2017-03-05 — about 7,900 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 6.2 53 km ESE of Old Harbor, Alaska · 30 km SSE of this epicentre
  2. 5.9 25 km E of Old Harbor, Alaska · 18 km SW of this epicentre
  3. 5.6 45 km SSE of Chiniak, Alaska · 48 km E of this epicentre
  4. 5.6 13 km S of Chiniak, Alaska · 34 km NE of this epicentre
  5. 5.4 36 km SSW of Chiniak, Alaska · 15 km E 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 57.2830, -152.6887. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Kodiak Island Borough, AK 87 km (54 mi) WNW earthquakes near Kodiak Island Borough

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. 2.3 8 km SSE of Womens Bay, Alaska
  2. 1.5 4 km SSW of Kodiak Station, Alaska
  3. 1.7 34 km NNE of Old Harbor, Alaska
  4. 1.8 34 km NNE of Old Harbor, Alaska
  5. 1.7 28 km SSE of Old Harbor, Alaska
  6. 2.0 38 km E of Old Harbor, Alaska
  7. 1.9 Kodiak Island region, Alaska
  8. 1.7 16 km NNE of Old Harbor, Alaska
  9. 1.9 Kodiak Island region, Alaska
  10. 2.1 32 km SSE of Old Harbor, Alaska
  11. 1.9 33 km NE of Old Harbor, Alaska
  12. 2.5 9 km SSW of Womens Bay, Alaska
  13. 2.9 33 km SW of Womens Bay, Alaska
  14. 1.8 33 km SSE of Old Harbor, Alaska
  15. 1.6 23 km SSW of Womens 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.