QuakeIndex

Earthquake · reviewed by a seismologist

M 5.4mww

43 km SSE of Old Harbor, Alaska

· 12 km deep · released about 1.9 kilotons of TNT

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10 km30 km60 km120 km N Kodiak Island Borough 110 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 5.4 (mww)
Depth
12 km below the surface
Felt
110 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Kodiak Island Borough, 110 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 599 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 110 people have reported feeling it to USGS.

How big was it?

This earthquake released about 1.9 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 89× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4× the energy of this one
  3. Magna, Utah 2020 M 5.7 2.8× the energy of this one
  4. This earthquake M 5.4 about 1.9 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 4,000× 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 56.8378, -153.0480. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Kodiak Island Borough, AK 110 km (68 mi) SSE of here earthquakes near Kodiak Island Borough

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

Aftershocks so far

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

  1. 1.9 24 km SSE of Old Harbor, Alaska
  2. 2.1 26 km SSW of Old Harbor, Alaska
  3. 2.2 70 km SE of Old Harbor, Alaska
  4. 1.9 38 km SSE of Old Harbor, Alaska
  5. 3.0 47 km ESE of Akhiok, Alaska
  6. 2.0 47 km SSE of Old Harbor, Alaska
  7. 2.9 45 km SSE of Old Harbor, Alaska
  8. 1.9 45 km SSE of Old Harbor, Alaska
  9. 3.5 40 km SSE of Old Harbor, Alaska
  10. 1.9 41 km SSE of Old Harbor, Alaska
  11. 2.1 42 km SSE of Old Harbor, Alaska
  12. 2.0 34 km SSE of Old Harbor, Alaska
  13. 2.8 42 km SSE of Old Harbor, Alaska
  14. 4.2 41 km SSE of Old Harbor, Alaska
  15. 1.9 6 km SW of Old Harbor, 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 5.4 on 2017-05-11.

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

On USGS

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