QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

207 km SSE of Unalaska, Alaska

· 17 km deep · released about 1,300 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 3.1 (ml)
Depth
17 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1338 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 250,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 7,900× the energy of this one
  4. This earthquake M 3.1 about 1,300 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.4× 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.

Where

Epicentre 52.3390, -164.7874. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.2 208 km SSE of Unalaska, Alaska
  2. 2.2 230 km SSE of Unalaska, Alaska
  3. 2.2 197 km SSE of Unalaska, Alaska
  4. 2.6 206 km SSE of Akutan, Alaska
  5. 3.2 230 km SSE of Akutan, Alaska
  6. 2.2 196 km SSE of Unalaska, Alaska
  7. 2.6 183 km SSE of Unalaska, Alaska
  8. 2.0 181 km SSE of Unalaska, Alaska
  9. 2.7 179 km SSE of Akutan, Alaska
  10. 2.3 192 km SSE of Unalaska, Alaska
  11. 2.7 207 km SSE of Unalaska, Alaska
  12. 2.4 171 km SSE of Akutan, Alaska
  13. 3.2 210 km SSE of Unalaska, Alaska
  14. 2.9 208 km SSE of Unalaska, Alaska
  15. 2.5 162 km SSE of Unalaska, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.1 on 2018-12-23 — it released about 32 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.