QuakeIndex

Earthquake · reviewed by a seismologist

M 4.8mb

Southern Alaska

Yes. A magnitude 4.8 earthquake was recorded in Southern Alaska, at 7:18 am AKDT on 24 September 2022 (15:18 UTC), 41 km deep. 129 people have reported feeling it to USGS.

· 41 km deep · released about 240 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Copper River Census Area 106 kmChugach Census Area 116 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 4.8 (mb)
Depth
41 km below the surface
Felt
129 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Copper River Census Area, 106 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1441 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, people at rest would likely notice it out to about 165 km (103 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 240 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 710× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 32× the energy of this one
  3. Magna, Utah 2020 M 5.7 22× the energy of this one
  4. This earthquake M 4.8 about 240 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 500× 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 (31 mi) since our catalogue begins in 2016. The previous largest was M 4.0 on 2017-03-03.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.1 48 km SSE of Nelchina, Alaska · 45 km WNW 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 61.4915, -145.5887. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Copper River Census Area, AK 106 km (66 mi) NE earthquakes near Copper River Census Area
Chugach Census Area, AK 116 km (72 mi) SSW earthquakes near Chugach Census Area

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. 1.7 44 km W of Tonsina, Alaska
  2. 2.0 41 km ENE of Valdez, Alaska
  3. 1.5 37 km NNE of Valdez, Alaska
  4. 2.6 32 km SSW of Tonsina, Alaska
  5. 2.1 51 km S of Tonsina, Alaska
  6. 1.8 48 km S of Tolsona, Alaska
  7. 1.8 36 km WSW of Tonsina, Alaska
  8. 2.2 39 km NE of Valdez, Alaska
  9. 1.7 44 km WSW of Tonsina, Alaska
  10. 1.8 43 km W of Tonsina, Alaska
  11. 1.7 47 km SSW of Tonsina, Alaska
  12. 2.3 34 km S of Tolsona, Alaska
  13. 2.2 37 km SSW of Tonsina, Alaska
  14. 2.3 40 km ENE of Valdez, Alaska
  15. 1.9 39 km NNE of Valdez, 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.