QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0ml

136 km ESE of Nikolski, Alaska

Yes. A magnitude 3.0 earthquake was recorded 136 km ESE of Nikolski, Alaska at 21:10 UTC on 2020-02-27, 10 km deep.

· 10 km deep · released about 950 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 3.0 (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 2369 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 5.9 on 2017-05-24 — about 22,000 times the energy of this one.

Before 2016, the USGS record lists 48 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.0 Fox Islands, Aleutian Islands, Alaska · 39 km WSW of this epicentre
  2. 6.7 103 km SE of Nikolski, Alaska · 49 km WSW of this epicentre
  3. 6.5 127 km E of Nikolski, Alaska · 24 km N of this epicentre
  4. 6.4 118 km E of Nikolski, Alaska · 28 km NNW of this epicentre
  5. 6.4 123 km ESE of Nikolski, Alaska · 14 km WNW 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 52.5388, -166.9445. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.6 125 km S of Unalaska, Alaska
  2. 1.9 141 km ESE of Nikolski, Alaska
  3. 2.9 126 km S of Unalaska, Alaska
  4. 2.2 126 km S of Unalaska, Alaska
  5. 1.7 102 km E of Nikolski, Alaska
  6. 1.8 121 km S of Unalaska, Alaska
  7. 3.6 119 km E of Nikolski, Alaska
  8. 2.6 105 km S of Unalaska, Alaska
  9. 3.0 142 km ESE of Nikolski, Alaska
  10. 2.6 131 km S of Unalaska, Alaska
  11. 1.6 104 km E of Nikolski, Alaska
  12. 1.8 107 km E of Nikolski, Alaska
  13. 2.3 124 km S of Unalaska, Alaska
  14. 2.1 146 km ESE of Nikolski, Alaska
  15. 2.9 102 km SSW 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.

On USGS

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