QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0ml

7 km S of Big Lake, Alaska

· 32 km deep · released about 15 tons of TNT

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10 km30 km60 km120 km N Anchorage Municipality 47 kmMatanuska-Susitna 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 4.0 (ml)
Depth
32 km below the surface
Felt
183 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Anchorage Municipality, 47 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2136 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 183 people have reported feeling it to USGS.

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.

Where

Epicentre 61.4588, -149.9364. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Anchorage Municipality, AK 47 km (29 mi) NW of here earthquakes near Anchorage Municipality
Matanuska-Susitna Borough, AK 93 km (57 mi) SSW of here earthquakes near Matanuska-Susitna Borough

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

Aftershocks so far

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

  1. 1.7 22 km S of Susitna, Alaska
  2. 1.5 4 km E of Big Lake, Alaska
  3. 1.5 6 km SW of Big Lake, Alaska
  4. 1.5 14 km SW of Anchorage, Alaska
  5. 2.3 5 km NW of Point MacKenzie, Alaska
  6. 2.6 6 km S of Houston, Alaska
  7. 1.7 9 km ESE of Elmendorf Air Force Base, Alaska
  8. 2.3 5 km SE of Willow, Alaska
  9. 1.7 Southern Alaska
  10. 1.6 9 km SW of Point MacKenzie, Alaska
  11. 2.2 22 km WSW of Anchorage, Alaska
  12. 3.0 7 km NNE of Point MacKenzie, Alaska
  13. 2.1 8 km WSW of Point MacKenzie, Alaska
  14. 1.6 4 km SSW of Big Lake, Alaska
  15. 1.5 6 km N of Meadow Lakes, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 7.1 on 2018-11-30 — it released about 45,000 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.