QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5ml

192 km SSW of Adak, Alaska

Yes. A magnitude 2.5 earthquake was recorded 192 km SSW of Adak, Alaska at 14:16 UTC on 2026-06-21, 1.6 km deep.

· 1.6 km deep · released about 170 lb 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 2.5 (ml)
Depth
1.6 km below the surface
Felt
no reports yet
Nearest mapped fault
Alaska-Aleutian subduction zone, 6 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 143 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, people at rest would likely notice it out to about 22 km (14 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 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 4.8 on 2018-08-10 — about 2,800 times the energy of this one.

Before 2016, the USGS record lists 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.5 184 km SSW of Adak, Alaska · 46 km ESE of this epicentre
  2. 6.0 207 km SW of Adak, Alaska · 34 km WNW of this epicentre
  3. 6.0 161 km SSW of Adak, Alaska · 45 km ENE of this epicentre
  4. 5.8 150 km SW of Adak, Alaska · 43 km NNE of this epicentre
  5. 5.8 192 km SSW of Adak, Alaska · 48 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 50.4360, -178.1720. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.2 236 km SSW of Adak, Alaska
  2. 2.8 148 km SW of Adak, Alaska
  3. 3.6 165 km SSW of Adak, 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.