QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

171 km SE of Unalaska, Alaska

· 21 km deep · released about 43 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 2.1 (ml)
Depth
21 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1451 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 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.

Where

Epicentre 52.6447, -164.9963. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.9 184 km SSE of Unalaska, Alaska
  2. 2.7 194 km SSE of Unalaska, Alaska
  3. 2.3 161 km SSE of Unalaska, Alaska
  4. 2.7 179 km SE of Unalaska, Alaska
  5. 2.4 198 km SSE of Unalaska, Alaska
  6. 3.3 174 km SSE of Unalaska, Alaska
  7. 2.9 188 km SSE of Unalaska, Alaska
  8. 3.0 175 km SSE of Unalaska, Alaska
  9. 2.4 197 km SSE of Unalaska, Alaska
  10. 2.2 170 km SSE of Unalaska, Alaska
  11. 2.9 202 km SSE of Unalaska, Alaska
  12. 2.2 193 km SSE of Unalaska, Alaska
  13. 3.2 201 km SSE of Unalaska, Alaska
  14. 3.1 218 km SSE of Unalaska, Alaska
  15. 2.9 195 km SSE 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.7 on 2020-10-21 — it released about 7,900 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.