QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6ml

Earthquake near Sutton-Alpine, AK

No earthquake was likely felt in Sutton-Alpine in the 24 hours to 3:39 pm AKST (00:39 UTC). The last one was M 4.4, 100 km (62 mi) E, at 11:11 am AKDT on 30 October 2026, estimated intensity II (weak) in town; 54 felt reports to USGS. Every earthquake near Sutton-Alpine

This page: a magnitude 1.6 earthquake was recorded 23 km (14 mi) north of Sutton-Alpine, AK, at 11:52 pm AKST on 21 January 2021 (08:52 UTC), 11 km deep.

USGS: 16 km NNW of Sutton-Alpine, Alaska

95 km (59 mi) NE of Anchorage, AK

11:52 pm AKST, Jan 21, 2021 · · 11 km deep · released about 7.6 lb of TNT

Every earthquake near Sutton-Alpine Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Matanuska-Susitna Borough 51 kmAnchorage Municipality 86 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
11:52 pm AKST on 21 January 2021 ()
Where
23 km (14 mi) north of Sutton-Alpine, AK · earthquakes near Sutton-Alpine
Magnitude
M 1.6 (ml)
Depth
11 km below the surface
Felt
no reports yet
Nearest
Matanuska-Susitna Borough, 51 km NW
Nearest mapped fault
Castle Mountain fault, 13 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 2108 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 4 km (2 mi) from the epicentre. In Sutton-Alpine, 23 km away, the estimate is intensity II (weak). 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.

Earthquakes near other towns within 30 km: Fishhook.

How big was it?

This earthquake released about 7.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
  3. Around the size people start to feel M 3.0 130× the energy of this one
  4. This earthquake M 1.6 about 7.6 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 4.3 on 2018-02-28 — about 11,000 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.9 23 km NE of Willow, Alaska · 46 km W of this epicentre
  2. 5.8 37 km ENE of Susitna North, Alaska · 46 km NNW of this epicentre
  3. 5.8 14 km NNE of Fishhook, Alaska · 14 km WSW of this epicentre
  4. 5.1 21 km SSE of Susitna North, Alaska · 44 km W of this epicentre
  5. 5.1 25 km ENE of Susitna North, Alaska · 46 km NW 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 61.9170, -148.8619. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Matanuska-Susitna Borough, AK 51 km (32 mi) NW earthquakes near Matanuska-Susitna Borough
Anchorage Municipality, AK 86 km (53 mi) SSW earthquakes near Anchorage Municipality

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

Aftershocks so far

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

  1. 1.9 23 km NNW of Chickaloon, Alaska
  2. 1.6 30 km N of Fishhook, Alaska
  3. 1.6 39 km N of Chickaloon, Alaska
  4. 2.1 40 km NNW of Sutton-Alpine, Alaska
  5. 2.0 42 km N of Chickaloon, Alaska
  6. 1.6 61 km N of Chickaloon, Alaska
  7. 1.7 11 km SSE of Chickaloon, Alaska
  8. 2.4 51 km NNW of Chickaloon, Alaska
  9. 2.0 14 km NNW of Fishhook, Alaska
  10. 1.6 32 km E of Susitna North, Alaska
  11. 1.5 7 km SSE of Sutton-Alpine, Alaska
  12. 1.7 51 km N of Chickaloon, Alaska
  13. 2.5 8 km NW of Fishhook, Alaska
  14. 1.9 35 km N of Sutton-Alpine, Alaska
  15. 3.3 28 km ESE of Susitna North, 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.