QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

85 km E of Cantwell, Alaska

Yes. A magnitude 1.5 earthquake was recorded 85 km E of Cantwell, Alaska, at 10:47 pm AKDT on 9 August 2020 (06:47 UTC), 76 km deep.

· 76 km deep · released about 5.4 lb 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 1.5 (ml)
Depth
76 km below the surface
Felt
no reports yet
Nearest
Matanuska-Susitna Borough, 164 km SW
Nearest mapped fault
Susitna Glacier fault, 12 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 2269 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause 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 5.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.9 2002 Denali Fault, Alaska Earthquake · 24 km NNW of this epicentre
  2. 6.6 53 km ENE of Cantwell, Alaska · 40 km WNW of this epicentre
  3. 5.6 70 km W of Paxson, Alaska · 37 km SSE of this epicentre
  4. 5.6 70 km W of Paxson, Alaska · 37 km SSE of this epicentre
  5. 5.6 70 km W of Paxson, Alaska · 37 km SSE 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 63.3182, -147.2455. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Matanuska-Susitna Borough, AK 164 km (102 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

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

  1. 1.7 62 km ESE of McKinley Park, Alaska
  2. 2.0 81 km ESE of McKinley Park, Alaska
  3. 1.5 80 km ESE of Cantwell, Alaska
  4. 2.1 61 km ESE of McKinley Park, Alaska
  5. 2.8 72 km SW of Delta Junction, Alaska
  6. 2.0 66 km E of Cantwell, Alaska
  7. 1.6 61 km ESE of McKinley Park, Alaska
  8. 2.2 82 km ESE of McKinley Park, Alaska
  9. 1.5 72 km SSW of Harding-Birch Lakes, Alaska
  10. 1.8 82 km ESE of McKinley Park, Alaska
  11. 1.8 86 km WNW of Paxson, Alaska
  12. 1.6 75 km E of Cantwell, Alaska
  13. 1.6 81 km ESE of McKinley Park, Alaska
  14. 2.8 80 km E of Cantwell, Alaska
  15. 1.9 58 km E of Cantwell, 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.