QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

82 km SSW of Sand Point, Alaska

Yes. A magnitude 3.1 earthquake was recorded 82 km SSW of Sand Point, Alaska, at 7:56 pm AKDT on 16 August 2020 (03:56 UTC), 25 km deep.

· 25 km deep · released about 1,300 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Aleutians East Borough 91 km
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 3.1 (ml)
Depth
25 km below the surface
Felt
no reports yet
Nearest
Aleutians East Borough, 91 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2211 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 33 km (21 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 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 250,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 7,900× the energy of this one
  4. This earthquake M 3.1 about 1,300 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.4× 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 6.1 on 2020-07-28 — about 32,000 times the energy of this one.

Before 2016, the USGS record lists 47 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.1 90 km SE of King Cove, Alaska · 13 km WSW of this epicentre
  2. 7.0 71 km SE of King Cove, Alaska · 40 km WSW of this epicentre
  3. 6.8 73 km SW of Sand Point, Alaska · 24 km NW of this epicentre
  4. 6.6 72 km SE of King Cove, Alaska · 37 km WSW of this epicentre
  5. 6.4 101 km SSW of Sand Point, Alaska · 19 km SSW 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 54.6556, -160.9990. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aleutians East Borough, AK 91 km (57 mi) NW earthquakes near Aleutians East Borough

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

  1. 1.6 80 km SSW of Sand Point, Alaska
  2. 1.7 81 km SE of King Cove, Alaska
  3. 2.2 82 km SE of King Cove, Alaska
  4. 4.2 59 km SSW of Sand Point, Alaska
  5. 1.8 83 km SE of King Cove, Alaska
  6. 2.0 102 km S of Sand Point, Alaska
  7. 1.6 64 km S of Sand Point, Alaska
  8. 1.7 83 km SE of King Cove, Alaska
  9. 1.6 86 km SSW of Sand Point, Alaska
  10. 1.5 86 km S of Sand Point, Alaska
  11. 1.8 94 km SSW of Sand Point, Alaska
  12. 2.0 95 km SSW of Sand Point, Alaska
  13. 1.6 83 km SSW of Sand Point, Alaska
  14. 1.5 83 km SSW of Sand Point, Alaska
  15. 1.5 64 km SSW 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.