QuakeIndex

Earthquake · automatic estimate, may change

M 2.5ml

46 km S of Old Harbor, Alaska

Yes. A magnitude 2.5 earthquake was recorded 46 km S of Old Harbor, Alaska, at 9:28 am AKDT on 17 September 2025 (17:28 UTC), 114 km deep. The magnitude and location are an automatic first estimate and may change.

· 114 km deep · released about 170 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Kodiak Island Borough 111 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 2.5 (ml)
Depth
114 km below the surface
Felt
no reports yet
Nearest
Kodiak Island Borough, 111 km NNW
Status
Automatic — a machine’s first estimate, which may change

USGS · last changed by USGS · we first saw it 422 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. 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 170 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 89,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 63,000× the energy of this one
  3. Around the size people start to feel M 3.0 5.6× the energy of this one
  4. This earthquake M 2.5 about 170 lb of TNT

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 5.4 on 2023-02-21 — about 22,000 times the energy of this one.

Before 2016, the USGS record lists 36 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 47 km S of Old Harbor, Alaska · 5 km WSW of this epicentre
  2. 6.6 88 km SSE of Old Harbor, Alaska · 44 km SSE of this epicentre
  3. 6.5 85 km SSE of Old Harbor, Alaska · 39 km SSE of this epicentre
  4. 6.4 95 km S of Old Harbor, Alaska · 49 km SSE of this epicentre
  5. 6.2 19 km SW of Old Harbor, Alaska · 39 km NNW 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 56.7845, -153.2090. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Kodiak Island Borough, AK 111 km (69 mi) NNW earthquakes near Kodiak Island Borough

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

Aftershocks so far

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

  1. 2.2 31 km SSE of Old Harbor, Alaska
  2. 2.0 22 km WSW of Old Harbor, Alaska
  3. 2.4 53 km SSE of Old Harbor, Alaska
  4. 1.9 30 km SSE of Old Harbor, Alaska
  5. 2.4 46 km SE of Akhiok, Alaska
  6. 2.8 32 km ESE of Akhiok, Alaska
  7. 2.1 53 km SSE of Old Harbor, Alaska
  8. 2.4 35 km ESE of Old Harbor, Alaska
  9. 2.1 58 km SE of Old Harbor, Alaska
  10. 1.9 26 km SW of Old Harbor, Alaska
  11. 1.9 30 km SE of Old Harbor, Alaska
  12. 1.8 11 km SE of Old Harbor, Alaska
  13. 2.3 61 km SE of Akhiok, Alaska
  14. 2.5 35 km SSE of Old Harbor, Alaska
  15. 2.0 35 km SE 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.

On USGS

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