QuakeIndex

Earthquake · reviewed by a seismologist

M 3.2ml

181 km E of Atka, Alaska

Yes. A magnitude 3.2 earthquake was recorded 181 km E of Atka, Alaska at 19:49 UTC on 2020-07-24, 118 km deep.

· 118 km deep · released about 1,900 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 3.2 (ml)
Depth
118 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2233 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 1,900 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 180,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 7,900× the energy of this one
  3. Magna, Utah 2020 M 5.7 5,600× the energy of this one
  4. This earthquake M 3.2 about 1,900 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 2× 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 4.6 on 2016-01-18 — about 130 times the energy of this one.

Before 2016, the USGS record lists 32 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 170 km E of Atka, Alaska · 35 km SSW of this epicentre
  2. 6.2 173 km WSW of Nikolski, Alaska · 19 km NE of this epicentre
  3. 6.1 188 km E of Atka, Alaska · 27 km SSE of this epicentre
  4. 6.0 177 km WSW of Nikolski, Alaska · 32 km SE of this epicentre
  5. 6.0 164 km WSW of Nikolski, Alaska · 34 km ESE 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 52.4772, -171.5713. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 5.0 172 km ENE of Atka, Alaska
  2. 3.5 173 km E of Atka, Alaska
  3. 2.3 151 km WSW of Nikolski, Alaska
  4. 2.3 151 km WSW of Nikolski, Alaska
  5. 2.3 151 km WSW of Nikolski, Alaska
  6. 3.4 174 km WSW of Nikolski, Alaska
  7. 2.3 176 km ENE of Atka, Alaska
  8. 3.2 176 km E of Atka, Alaska
  9. 3.7 147 km ENE of Atka, Alaska
  10. 2.7 169 km E of Atka, Alaska
  11. 2.8 187 km WSW of Nikolski, Alaska
  12. 3.1 154 km E of Atka, Alaska
  13. 3.5 178 km E of Atka, Alaska
  14. 3.6 167 km E of Atka, Alaska
  15. 3.2 169 km WSW of Nikolski, 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.