QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8mb

183 km SE of Akutan, Alaska

Yes. A magnitude 3.8 earthquake was recorded 183 km SE of Akutan, Alaska at 01:02 UTC on 2018-09-08, 10 km deep.

· 10 km deep · released about 7.6 tons 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 3.8 (mb)
Depth
10 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 2538 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 82 km (51 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 7.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 22,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 710× the energy of this one
  4. This earthquake M 3.8 about 7.6 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 16× more

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 7.9 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 184 km SE of Akutan, Alaska · 48 km NE of this epicentre
  2. 6.2 156 km SE of Akutan, Alaska · 34 km N of this epicentre
  3. 5.5 218 km SE of Akutan, Alaska · 36 km SSE of this epicentre
  4. 5.4 149 km SE of Akutan, Alaska · 34 km NW of this epicentre
  5. 5.1 200 km SE of Akutan, Alaska · 26 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 52.8854, -163.9759. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.3 140 km SE of Akutan, Alaska
  2. 3.0 139 km SE of Akutan, Alaska
  3. 1.8 139 km SE of Akutan, Alaska
  4. 2.3 232 km SE of Akutan, Alaska
  5. 1.8 159 km SE of Akutan, Alaska
  6. 3.0 147 km SE of Akutan, Alaska
  7. 4.0 140 km SE of Akutan, Alaska
  8. 1.9 134 km SE of Akutan, Alaska
  9. 3.9 138 km SE of Akutan, Alaska
  10. 2.7 147 km SE of Akutan, Alaska
  11. 3.3 136 km SE of Akutan, Alaska
  12. 2.8 149 km SE of Akutan, Alaska
  13. 2.8 163 km SE of Akutan, Alaska
  14. 2.2 196 km SSE of Akutan, Alaska
  15. 3.2 220 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.