QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

74 km W of Karluk, Alaska

Yes. A magnitude 2.1 earthquake was recorded 74 km W of Karluk, Alaska at 23:22 UTC on 2021-08-07, 15 km deep.

· 15 km deep · released about 43 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lake and Peninsula Borough 81 kmKodiak Island Borough 108 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 2.1 (ml)
Depth
15 km below the surface
Felt
no reports yet
Nearest
Lake and Peninsula Borough, 81 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1905 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 8 km (5 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 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 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 5.3 on 2018-05-11 — about 63,000 times the energy of this one.

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

  1. 5.5 64 km SW of Karluk, Alaska · 39 km SE of this epicentre
  2. 5.4 60 km E of Ugashik, Alaska · 43 km W of this epicentre
  3. 5.2 55 km WSW of Karluk, Alaska · 23 km ESE of this epicentre
  4. 5.0 54 km WNW of Karluk, Alaska · 34 km NE 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 57.4928, -155.6833. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake and Peninsula Borough, AK 81 km (50 mi) NNW earthquakes near Lake and Peninsula Borough
Kodiak Island Borough, AK 108 km (67 mi) ENE earthquakes near Kodiak Island Borough

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

Aftershocks so far

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

  1. 2.1 72 km SW of Karluk, Alaska
  2. 1.5 65 km W of Karluk, Alaska
  3. 1.6 80 km SW of Karluk, Alaska
  4. 2.0 76 km WNW of Akhiok, Alaska
  5. 1.5 52 km WSW of Karluk, Alaska
  6. 2.2 83 km ESE of Egegik, Alaska
  7. 2.0 73 km WNW of Akhiok, Alaska
  8. 1.5 60 km WNW of Karluk, Alaska
  9. 2.0 70 km WNW of Akhiok, Alaska
  10. 1.9 47 km W of Karluk, Alaska
  11. 2.1 91 km ESE of Egegik, Alaska
  12. 1.5 88 km ENE of Ugashik, Alaska
  13. 2.1 72 km WSW of Karluk, Alaska
  14. 1.5 86 km WSW of Karluk, Alaska
  15. 2.0 74 km W of Karluk, 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.