QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5ml

176 km SE of Akutan, Alaska

Yes. A magnitude 2.5 earthquake was recorded 176 km SE of Akutan, Alaska at 15:49 UTC on 2018-02-02, 32 km deep.

· 32 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
32 km below the surface
Felt
no reports yet
Nearest mapped fault
Alaska-Aleutian subduction zone, 16 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 1190 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 4.4 on 2016-07-19 — about 710 times the energy of this one.

Before 2016, the USGS record lists 11 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 136 km SE of Akutan, Alaska · 49 km NNW of this epicentre
  2. 6.2 184 km SE of Akutan, Alaska · 35 km NE of this epicentre
  3. 6.2 156 km SE of Akutan, Alaska · 22 km NNW of this epicentre
  4. 6.0 195 km S of False Pass, Alaska · 47 km ENE of this epicentre
  5. 5.5 218 km SE of Akutan, Alaska · 46 km SSE 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 53.0072, -163.8988. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 5.5 160 km ESE of Akutan, Alaska
  2. 3.4 197 km SE of Akutan, Alaska
  3. 2.4 172 km S of False Pass, Alaska
  4. 2.5 165 km S of False Pass, Alaska
  5. 2.9 162 km S of False Pass, Alaska
  6. 2.5 164 km S of False Pass, Alaska
  7. 2.4 165 km S of False Pass, Alaska
  8. 2.5 170 km S of False Pass, Alaska
  9. 2.6 166 km S of False Pass, Alaska
  10. 2.4 165 km S of False Pass, Alaska
  11. 2.2 163 km S of False Pass, Alaska
  12. 2.4 165 km S of False Pass, Alaska
  13. 2.2 135 km SE of Akutan, Alaska
  14. 2.5 175 km SE of Akutan, Alaska
  15. 2.8 130 km SE of Akutan, 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.