QuakeIndex

Earthquake · reviewed by a seismologist

M 3.3ml

Central Alaska

Yes. A magnitude 3.3 earthquake was recorded in Central Alaska, at 1:31 am AKDT on 23 April 2023 (09:31 UTC), 108 km deep. 1 person has reported feeling it to USGS.

· 108 km deep · released about 1.3 tons of TNT

10 km30 km60 km120 km N Matanuska-Susitna Borough 92 kmDenali Borough 93 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 3.3 (ml)
Depth
108 km below the surface
Felt
1 report · strongest reported intensity III
Nearest
Matanuska-Susitna Borough, 92 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1222 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 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 1.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 130,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 5,600× the energy of this one
  3. Magna, Utah 2020 M 5.7 4,000× the energy of this one
  4. This earthquake M 3.3 about 1.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2.8× 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 5.3 on 2016-05-15 — about 1,000 times the energy of this one.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.7 66 km ESE of Denali National Park, Alaska · 36 km N of this epicentre
  2. 5.5 59 km SE of Denali National Park, Alaska · 30 km NNW of this epicentre
  3. 5.4 70 km WSW of Cantwell, Alaska · 37 km NE of this epicentre
  4. 5.4 48 km N of Petersville, Alaska · 4 km NNE of this epicentre
  5. 5.3 71 km SE of Denali National Park, Alaska · 34 km NNE 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 62.8944, -150.6789. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Matanuska-Susitna Borough, AK 92 km (57 mi) SE earthquakes near Matanuska-Susitna Borough
Denali Borough, AK 93 km (58 mi) NNE earthquakes near Denali Borough

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

Aftershocks so far

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

  1. 1.9 51 km N of Petersville, Alaska
  2. 1.6 61 km NNW of Petersville, Alaska
  3. 1.5 72 km W of Cantwell, Alaska
  4. 1.6 60 km NNW of Petersville, Alaska
  5. 1.9 52 km NNW of Petersville, Alaska
  6. 1.8 74 km N of Petersville, Alaska
  7. 2.8 71 km ESE of Denali National Park, Alaska
  8. 1.9 68 km WSW of Cantwell, Alaska
  9. 1.5 71 km ESE of Denali National Park, Alaska
  10. 1.5 68 km WSW of Cantwell, Alaska
  11. 1.9 48 km SE of Denali National Park, Alaska
  12. 2.3 66 km ESE of Denali National Park, Alaska
  13. 2.8 60 km SE of Denali National Park, Alaska
  14. 2.1 6 km ENE of Petersville, Alaska
  15. 2.0 38 km N of Petersville, 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.