QuakeIndex

Earthquake · reviewed by a seismologist

M 4.5mb

72 km SSE of False Pass, Alaska

Yes. A magnitude 4.5 earthquake was recorded 72 km SSE of False Pass, Alaska, at 8:29 am AKDT on 23 March 2016 (16:29 UTC), 53 km deep.

· 53 km deep · released about 85 tons of TNT

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10 km30 km60 km120 km N Aleutians East Borough 119 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 4.5 (mb)
Depth
53 km below the surface
Felt
no reports yet
Nearest
Aleutians East Borough, 119 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1201 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 129 km (80 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 85 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 2,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 89× the energy of this one
  3. Magna, Utah 2020 M 5.7 63× the energy of this one
  4. This earthquake M 4.5 about 85 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 180× 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

The largest earthquake within 50 km (31 mi) since our catalogue begins in 2016. No other earthquake of M4 or more has been recorded this close in that time.

Before 2016, the USGS record lists 23 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.5 47 km SE of False Pass, Alaska · 30 km N of this epicentre
  2. 6.5 88 km SE of False Pass, Alaska · 18 km ESE of this epicentre
  3. 5.8 112 km SE of False Pass, Alaska · 40 km SE of this epicentre
  4. 5.8 60 km SSW of King Cove, Alaska · 32 km NNE of this epicentre
  5. 5.7 88 km SE of False Pass, Alaska · 18 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 54.2936, -162.8305. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aleutians East Borough, AK 119 km (74 mi) NNE earthquakes near Aleutians East Borough

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

Aftershocks so far

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

  1. 2.4 73 km SE of False Pass, Alaska
  2. 2.4 93 km S of False Pass, Alaska
  3. 2.4 76 km S of King Cove, Alaska
  4. 2.1 89 km SSE of False Pass, Alaska
  5. 2.3 108 km SSE of False Pass, Alaska
  6. 2.4 104 km SSE of False Pass, Alaska
  7. 2.1 56 km SE of False Pass, Alaska
  8. 3.0 97 km SE of False Pass, Alaska
  9. 2.6 110 km SSE of False Pass, Alaska
  10. 2.1 102 km S of False Pass, Alaska
  11. 1.8 38 km SE of False Pass, Alaska
  12. 2.7 104 km S of False Pass, Alaska
  13. 2.3 46 km SSW of King Cove, Alaska
  14. 2.1 58 km S of King Cove, Alaska
  15. 1.9 42 km SE of False Pass, 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.