QuakeIndex

Earthquake · reviewed by a seismologist

M 5.5mww

92 km S of Nikolski, Alaska

Yes. A magnitude 5.5 earthquake was recorded 92 km S of Nikolski, Alaska at 19:25 UTC on 2026-03-05, 17 km deep. 1 person has reported feeling it to USGS.

· 17 km deep · released about 2.7 kilotons 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 5.5 (mww)
Depth
17 km below the surface
Felt
1 report · strongest reported intensity II
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 51 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 261 km (162 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 2.7 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 63× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2.8× the energy of this one
  3. Magna, Utah 2020 M 5.7 2× the energy of this one
  4. This earthquake M 5.5 about 2.7 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 5,600× 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 since 2016 was M 5.9 on 2025-09-03 — about 4 times the energy of this one.

Before 2016, the USGS record lists 160 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 77 km SSW of Nikolski, Alaska · 41 km NW of this epicentre
  2. 6.9 80 km SW of Nikolski, Alaska · 49 km NW of this epicentre
  3. 6.9 Fox Islands, Aleutian Islands, Alaska · 45 km NW of this epicentre
  4. 6.8 64 km SSW of Nikolski, Alaska · 48 km NW of this epicentre
  5. 6.7 75 km SSE of Nikolski, Alaska · 45 km ENE 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 52.1060, -168.9557. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.3 59 km S of Nikolski, Alaska
  2. 2.3 55 km SSW of Nikolski, Alaska
  3. 2.5 87 km SSW of Nikolski, Alaska
  4. 2.6 102 km SSW of Nikolski, Alaska
  5. 2.2 63 km SSW of Nikolski, Alaska
  6. 2.4 86 km SSW of Nikolski, Alaska
  7. 2.5 99 km SSW of Nikolski, Alaska
  8. 3.0 70 km SSW of Nikolski, Alaska
  9. 2.3 77 km S of Nikolski, Alaska
  10. 2.5 76 km S of Nikolski, Alaska
  11. 2.6 53 km SSE of Nikolski, Alaska
  12. 2.5 64 km S of Nikolski, Alaska
  13. 2.7 85 km SSW of Nikolski, Alaska
  14. 2.5 61 km SSW of Nikolski, Alaska
  15. 2.3 52 km S of Nikolski, 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.