QuakeIndex

Earthquake · reviewed by a seismologist

M 4.3mb

58 km SSE of Kokhanok, Alaska

Yes. A magnitude 4.3 earthquake was recorded 58 km SSE of Kokhanok, Alaska at 05:34 UTC on 2023-02-20, 131 km deep. 21 people have reported feeling it to USGS.

· 131 km deep · released about 43 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 4.3 (mb)
Depth
131 km below the surface
Felt
21 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
Nearest
Lake and Peninsula Borough, 143 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1294 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 it was probably too small to be felt, even directly above it. 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 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 4,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 180× the energy of this one
  3. Magna, Utah 2020 M 5.7 130× the energy of this one
  4. This earthquake M 4.3 about 43 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 89× 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 4.8 on 2019-03-07 — about 5.6 times the energy of this one.

Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 74 km S of Kokhanok, Alaska · 20 km SSW of this epicentre
  2. 6.0 62 km SSE of Kokhanok, Alaska · 5 km SE of this epicentre
  3. 5.6 72 km S of Kokhanok, Alaska · 16 km SSW of this epicentre
  4. 5.6 62 km SE of Kokhanok, Alaska · 22 km ENE of this epicentre
  5. 5.5 73 km SSE of Kokhanok, Alaska · 21 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 58.9321, -154.5175. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake and Peninsula Borough, AK 143 km (89 mi) SW earthquakes near Lake and Peninsula Borough

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

Aftershocks so far

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

  1. 1.5 62 km SSE of Kokhanok, Alaska
  2. 2.0 73 km SE of Kokhanok, Alaska
  3. 3.1 58 km SSE of Kokhanok, Alaska
  4. 1.5 57 km SSE of Kokhanok, Alaska
  5. 1.6 93 km NW of Aleneva, Alaska
  6. 1.9 91 km NW of Aleneva, Alaska
  7. 1.9 68 km SSE of Kokhanok, Alaska
  8. 1.6 82 km SSE of Kokhanok, Alaska
  9. 1.6 79 km S of Kokhanok, Alaska
  10. 2.1 86 km SSE of Kokhanok, Alaska
  11. 1.9 66 km S of Kokhanok, Alaska
  12. 1.5 97 km SSE of Kokhanok, Alaska
  13. 2.4 91 km NW of Aleneva, Alaska
  14. 2.0 62 km SSE of Kokhanok, Alaska
  15. 1.9 53 km S of Kokhanok, 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.