QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

156 km S of Adak, Alaska

Yes. A magnitude 2.1 earthquake was recorded 156 km S of Adak, Alaska at 08:01 UTC on 2024-07-22, 8.4 km deep.

· 8.4 km deep · released about 43 lb of TNT

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
Magnitude
M 2.1 (ml)
Depth
8.4 km below the surface
Felt
no reports yet
Nearest mapped fault
Alaska-Aleutian subduction zone, 1 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 807 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 15 km (9 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 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 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 4.7 on 2016-11-29 — about 7,900 times the energy of this one.

Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.4 146 km S of Adak, Alaska · 41 km WNW of this epicentre
  2. 6.3 159 km SSE of Adak, Alaska · 44 km ENE of this epicentre
  3. 5.8 176 km S of Adak, Alaska · 48 km WSW of this epicentre
  4. 5.8 164 km S of Adak, Alaska · 35 km WSW of this epicentre
  5. 5.7 Andreanof Islands, Aleutian Islands, Alaska · 35 km S 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 50.4842, -176.2618. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.6 168 km S of Adak, Alaska
  2. 3.2 176 km S of Adak, Alaska
  3. 2.2 156 km S of Adak, Alaska
  4. 3.0 117 km SSE of Adak, Alaska
  5. 2.3 114 km SSE of Adak, Alaska
  6. 2.5 173 km SSE of Adak, Alaska
  7. 2.4 147 km SSE of Adak, Alaska
  8. 2.8 153 km S of Adak, Alaska
  9. 2.5 145 km S of Adak, Alaska
  10. 2.8 136 km SSE of Adak, Alaska
  11. 2.9 169 km S of Adak, Alaska
  12. 2.7 143 km S of Adak, Alaska
  13. 2.5 188 km SSE of Adak, Alaska
  14. 2.5 145 km S of Adak, Alaska
  15. 3.4 138 km SSE 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.