QuakeIndex

Earthquake · reviewed by a seismologist

M 7.1mw

1 km SE of Point MacKenzie, Alaska

· 47 km deep · released about 670 kilotons of TNT

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10 km30 km60 km120 km N Anchorage Municipality 41 kmMatanuska-Susitna Borough 105 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 7.1 (mw)
Depth
47 km below the surface
Felt
2342 reports · strongest reported intensity VIII
Measured shaking
intensity VIII (ShakeMap)
USGS impact alert
orange
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Anchorage Municipality, 41 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 294 days ago

This was a major earthquake. Serious damage is likely near the epicentre. Follow official information from USGS and local authorities. 2342 people have reported feeling it to USGS.

How big was it?

This earthquake released about 670 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 8.1 would have released about 32 times as much.

  1. Great Alaska earthquake 1964 M 9.2 1,400× the energy of this one
  2. Tōhoku, Japan 2011 M 9.1 1,000× the energy of this one
  3. San Francisco 1906 M 7.9 16× the energy of this one
  4. This earthquake M 7.1 about 670 kilotons of TNT
  5. Loma Prieta, California 1989 M 6.9 this one released 2× more
  6. Northridge, California 1994 M 6.7 this one released 4× 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 61.3464, -149.9552. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Anchorage Municipality, AK 41 km (25 mi) WNW of here earthquakes near Anchorage Municipality
Matanuska-Susitna Borough, AK 105 km (65 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

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

  1. 2.3 7 km SSE of Big Lake, Alaska
  2. 2.3 10 km NW of Point MacKenzie, Alaska
  3. 2.4 6 km WSW of Knik, Alaska
  4. 2.5 8 km N of Point MacKenzie, Alaska
  5. 3.6 6 km NW of Point MacKenzie, Alaska
  6. 3.6 7 km WSW of Knik, Alaska
  7. 3.0 7 km NW of Point MacKenzie, Alaska
  8. 3.2 2 km SSE of Big Lake, Alaska
  9. 3.2 8 km NW of Point MacKenzie, Alaska
  10. 2.5 3 km NNW of Point MacKenzie, Alaska
  11. 3.0 6 km NW of Point MacKenzie, Alaska
  12. 3.2 8 km NW of Point MacKenzie, Alaska
  13. 3.0 8 km NW of Point MacKenzie, Alaska
  14. 3.2 5 km SW of Big Lake, Alaska
  15. 3.3 1 km SSE of Big Lake, 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 4.1 on 2018-03-30.

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

On USGS

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