QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

Southern Alaska

Yes. A magnitude 2.1 earthquake was recorded in Southern Alaska, at 5:25 pm AKST on 13 December 2020 (02:25 UTC), 36 km deep.

· 36 km deep · released about 43 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 2.1 (ml)
Depth
36 km below the surface
Felt
no reports yet
Nearest
Anchorage Municipality, 139 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2152 days ago

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

At this magnitude and depth it was probably too small to be felt, even directly above it. 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 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.4 23 km S of Glacier View, Alaska · 42 km SW of this epicentre
  2. 6.4 37 km SSE of Glacier View, Alaska · 43 km SSW of this epicentre
  3. 5.9 15 km N of Glacier View, Alaska · 35 km WNW of this epicentre
  4. 5.5 47 km SSE of Glacier View, Alaska · 49 km SSW of this epicentre
  5. 5.1 48 km NNW of Valdez, Alaska · 40 km SSE 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 61.8409, -147.0582. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 139 km (87 mi) WSW earthquakes near Anchorage Municipality

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

Aftershocks so far

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

  1. 1.6 48 km SSE of Nelchina, Alaska
  2. 1.6 25 km NNW of Eureka Roadhouse, Alaska
  3. 1.5 39 km SSE of Glacier View, Alaska
  4. 1.6 11 km SW of Eureka Roadhouse, Alaska
  5. 2.4 9 km W of Eureka Roadhouse, Alaska
  6. 1.5 35 km SE of Glacier View, Alaska
  7. 2.3 35 km N of Eureka Roadhouse, Alaska
  8. 2.1 39 km NNW of Valdez, Alaska
  9. 1.6 44 km SSE of Eureka Roadhouse, Alaska
  10. 2.4 39 km NNW of Valdez, Alaska
  11. 1.7 36 km NNW of Eureka Roadhouse, Alaska
  12. 1.7 47 km S of Nelchina, Alaska
  13. 1.9 30 km SE of Glacier View, Alaska
  14. 1.5 44 km NNW of Valdez, Alaska
  15. 1.6 46 km NNW of Valdez, 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.