QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9ml

127 km SSE of Sand Point, Alaska

Yes. A magnitude 2.9 earthquake was recorded 127 km SSE of Sand Point, Alaska, at 4:29 pm AKDT on 20 October 2020 (00:29 UTC), 31 km deep.

· 31 km deep · released about 680 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 2.9 (ml)
Depth
31 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2134 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 7 km (4 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 680 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 22,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 16,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.4× the energy of this one
  4. This earthquake M 2.9 about 680 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 7.6 on 2020-10-19 — about 11,000,000 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

  1. 6.6 85 km SE of Sand Point, Alaska · 48 km N of this epicentre
  2. 6.1 79 km SE of Sand Point, Alaska · 50 km NNW of this epicentre
  3. 5.9 113 km SE of Sand Point, Alaska · 36 km NNE of this epicentre
  4. 5.9 99 km SE of Sand Point, Alaska · 34 km N 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 54.3364, -159.5182. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.7 131 km SSE of Sand Point, Alaska
  2. 2.7 103 km SSE of Sand Point, Alaska
  3. 3.5 135 km SSE of Sand Point, Alaska
  4. 3.0 90 km SE of Sand Point, Alaska
  5. 3.1 135 km SSE of Sand Point, Alaska
  6. 2.7 113 km SSE of Sand Point, Alaska
  7. 3.0 124 km SSE of Sand Point, Alaska
  8. 3.1 121 km SSE of Sand Point, Alaska
  9. 2.5 100 km SSE of Sand Point, Alaska
  10. 2.6 106 km SSE of Sand Point, Alaska
  11. 3.2 113 km SE of Sand Point, Alaska
  12. 2.5 90 km SSE of Sand Point, Alaska
  13. 2.5 91 km SSE of Sand Point, Alaska
  14. 3.1 157 km SSE of Sand Point, Alaska
  15. 2.8 90 km SSE of Sand Point, 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.