QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

199 km S of Unalaska, Alaska

· 10 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
10 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1716 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 52.1095, -166.0236. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.2 192 km ESE of Nikolski, Alaska
  2. 2.6 184 km S of Unalaska, Alaska
  3. 3.0 177 km SSE of Unalaska, Alaska
  4. 3.5 185 km ESE of Nikolski, Alaska
  5. 2.4 194 km S of Unalaska, Alaska
  6. 2.3 197 km SSE of Unalaska, Alaska
  7. 2.7 209 km SSE of Unalaska, Alaska
  8. 3.0 158 km S of Unalaska, Alaska
  9. 3.7 155 km S of Unalaska, Alaska
  10. 2.0 205 km S of Unalaska, Alaska
  11. 2.6 192 km ESE of Nikolski, Alaska
  12. 2.3 200 km SSE of Unalaska, Alaska
  13. 3.4 169 km S of Unalaska, Alaska
  14. 4.2 165 km S of Unalaska, Alaska
  15. 2.8 181 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 5.2 on 2019-08-03 — it released about 1,400 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.