QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Unalaska, AK

No earthquake was likely felt in Unalaska in the 24 hours to 4:21 pm AKST (01:21 UTC). The last one was M 4.4, 117 km (72 mi) ESE, at 3:00 pm AKST on 11 November 2026, estimated intensity II (weak) in town. Every earthquake near Unalaska

This page: a magnitude 1.8 earthquake was recorded 9 km (6 mi) south of Unalaska, AK, at 1:12 am AKDT on 20 September 2026 (09:12 UTC), 12 km deep.

USGS: 8 km S of Unalaska, Alaska

1:12 am AKDT, Sep 20, 2026 · · 12 km deep · released about 15 lb of TNT

Every earthquake near Unalaska Felt it? Tell USGS Check my area
10 km30 km60 km120 km N
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
1:12 am AKDT on 20 September 2026 ()
Where
9 km (6 mi) south of Unalaska, AK · earthquakes near Unalaska
Magnitude
M 1.8 (ml)
Depth
12 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 49 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 7 km (4 mi) from the epicentre. In Unalaska, 9 km away, the estimate is intensity II (weak). 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.

Earthquakes near other towns within 30 km: Dutch Harbor.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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 5.3 on 2025-07-27 — about 180,000 times the energy of this one.

Before 2016, the USGS record lists 16 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 36 km ESE of Unalaska, Alaska · 33 km ESE of this epicentre
  2. 6.1 56 km SSW of Unalaska, Alaska · 48 km SSW of this epicentre
  3. 6.0 51 km SW of Unalaska, Alaska · 46 km WSW of this epicentre
  4. 5.9 27 km WNW of Dutch Harbor, Alaska · 32 km NW of this epicentre
  5. 5.9 13 km NE of Dutch Harbor, Alaska · 22 km NNE 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 53.7940, -166.5470. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. -0.4 15 km WNW of Dutch Harbor, Alaska
  2. -0.1 15 km W of Dutch Harbor, Alaska
  3. 0.6 15 km W of Dutch Harbor, Alaska
  4. 0.5 15 km W of Dutch Harbor, Alaska
  5. 0.6 15 km W of Dutch Harbor, Alaska
  6. -0.3 15 km W of Dutch Harbor, Alaska
  7. -0.2 15 km W of Dutch Harbor, Alaska
  8. 0.9 15 km W of Dutch Harbor, Alaska
  9. -0.2 15 km W of Dutch Harbor, Alaska
  10. -0.1 15 km W of Dutch Harbor, Alaska
  11. 1.1 15 km W of Dutch Harbor, Alaska
  12. 0.1 15 km W of Dutch Harbor, Alaska
  13. -0.4 15 km W of Dutch Harbor, Alaska
  14. -0.7 15 km W of Dutch Harbor, Alaska
  15. 0.2 15 km W of Dutch 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.