QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mwr

65 km ESE of Cantwell, Alaska

Yes. A magnitude 4.0 earthquake was recorded 65 km ESE of Cantwell, Alaska, at 5:29 pm AKDT on 13 August 2025 (01:29 UTC), 3.5 km deep. 30 people have reported feeling it to USGS.

· 3.5 km deep · released about 15 tons of TNT

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10 km30 km60 km120 km N
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 4.0 (mwr)
Depth
3.5 km below the surface
Felt
30 reports · strongest reported intensity III
Measured shaking
intensity IV (ShakeMap)
Nearest
Denali Borough, 127 km WNW
Nearest mapped fault
Susitna Glacier fault, 25 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 374 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 97 km (60 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 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 32× 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

Tied for the largest within 50 km (31 mi) since 2016, with M 4.0 on 2020-01-17.

Before 2016, the USGS record lists 11 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.9 2002 Denali Fault, Alaska Earthquake · 39 km NNE of this epicentre
  2. 6.6 53 km ENE of Cantwell, Alaska · 38 km NNW of this epicentre
  3. 5.6 70 km W of Paxson, Alaska · 42 km ESE of this epicentre
  4. 5.6 70 km W of Paxson, Alaska · 42 km ESE of this epicentre
  5. 5.6 70 km W of Paxson, Alaska · 42 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 63.1847, -147.7208. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Denali Borough, AK 127 km (79 mi) WNW earthquakes near Denali Borough
Matanuska-Susitna Borough, AK 137 km (85 mi) SW earthquakes near Matanuska-Susitna 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 66 km ESE of Cantwell, Alaska
  2. 2.3 69 km SSE of Cantwell, Alaska
  3. 1.9 67 km ESE of Cantwell, Alaska
  4. 2.8 70 km SE of Cantwell, Alaska
  5. 2.0 69 km E of Cantwell, Alaska
  6. 1.7 71 km E of Cantwell, Alaska
  7. 1.6 79 km ESE of Denali Park, Alaska
  8. 2.0 69 km E of Cantwell, Alaska
  9. 2.3 86 km ESE of Denali Park, Alaska
  10. 1.8 68 km ESE of Cantwell, Alaska
  11. 2.0 67 km ESE of Cantwell, Alaska
  12. 1.8 66 km ESE of Cantwell, Alaska
  13. 2.1 65 km ESE of Cantwell, Alaska
  14. 1.7 70 km ESE of Cantwell, Alaska
  15. 2.9 63 km ESE of Denali Park, 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.