QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0ml

145 km SSE of Atka, Alaska

Yes. A magnitude 3.0 earthquake was recorded 145 km SSE of Atka, Alaska at 17:33 UTC on 2020-03-11, 10 km deep.

· 10 km deep · released about 950 lb of TNT

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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 3.0 (ml)
Depth
10 km below the surface
Felt
no reports yet
Nearest mapped fault
Alaska-Aleutian subduction zone, 20 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 2358 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 35 km (22 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 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 350,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
  4. This earthquake M 3.0 about 950 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.

For this area

The largest earthquake within 50 km since 2016 was M 4.4 on 2019-06-06 — about 130 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 5.8 174 km SSE of Atka, Alaska · 39 km ESE of this epicentre
  2. 5.8 161 km SSE of Atka, Alaska · 33 km E of this epicentre
  3. 5.8 165 km SSE of Atka, Alaska · 31 km ESE of this epicentre
  4. 5.8 150 km SSE of Atka, Alaska · 36 km ENE of this epicentre
  5. 5.2 181 km SSE of Atka, Alaska · 44 km SE 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 50.9474, -173.5889. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.8 99 km SSE of Atka, Alaska
  2. 2.2 146 km S of Atka, Alaska
  3. 2.4 135 km SSE of Atka, Alaska
  4. 2.4 118 km SSE of Atka, Alaska
  5. 3.6 123 km SSE of Atka, Alaska
  6. 2.1 140 km SSE of Atka, Alaska
  7. 3.0 177 km SSE of Atka, Alaska
  8. 3.7 126 km SSE of Atka, Alaska
  9. 2.2 Andreanof Islands, Aleutian Islands, Alaska
  10. 2.8 143 km S of Atka, Alaska
  11. 2.7 100 km SSE of Atka, Alaska
  12. 2.6 121 km SSE of Atka, Alaska
  13. 2.6 138 km SSE of Atka, Alaska
  14. 2.9 151 km SSE of Atka, Alaska
  15. 2.2 181 km SSE of Atka, 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.