QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

211 km W of Adak, Alaska

Yes. A magnitude 1.5 earthquake was recorded 211 km W of Adak, Alaska at 10:44 UTC on 2023-09-07, 13 km deep.

· 13 km deep · released about 5.4 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 1.5 (ml)
Depth
13 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1151 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause 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 5.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 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 5.2 on 2016-11-23 — about 350,000 times the energy of this one.

Before 2016, the USGS record lists 74 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 207 km WSW of Adak, Alaska · 38 km SSE of this epicentre
  2. 6.9 203 km WSW of Adak, Alaska · 39 km SSE of this epicentre
  3. 6.9 231 km WSW of Adak, Alaska · 44 km SSW of this epicentre
  4. 6.8 235 km WSW of Adak, Alaska · 48 km SSW of this epicentre
  5. 6.7 237 km WSW of Adak, Alaska · 41 km SSW 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 51.6823, -179.6775. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.2 205 km WSW of Adak, Alaska
  2. 2.3 208 km WSW of Adak, Alaska
  3. 2.7 208 km WSW of Adak, Alaska
  4. 2.0 211 km W of Adak, Alaska
  5. 2.9 207 km W of Adak, Alaska
  6. 2.8 192 km W of Adak, Alaska
  7. 2.6 209 km W of Adak, Alaska
  8. 3.5 174 km W of Adak, Alaska
  9. 2.8 231 km W of Adak, Alaska
  10. 2.7 197 km WSW of Adak, Alaska
  11. 2.3 192 km WSW of Adak, Alaska
  12. 3.6 191 km W of Adak, Alaska
  13. 2.9 185 km WSW of Adak, Alaska
  14. 3.0 205 km W of Adak, Alaska
  15. 2.3 209 km W 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.