QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Tok, AK

USGS: 21 km NNE of Mentasta Lake, Alaska

10:01 am AKST, Mar 6, 2021 · · 17 km deep · released about 21 lb of TNT

Every earthquake near Tok Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Southeast Fairbanks Census Area 88 kmCopper River Census Area 119 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
10:01 am AKST on 6 March 2021 ()
Where
40 km (25 mi) SW of Tok, AK · earthquakes near Tok
Magnitude
M 1.9 (ml)
Depth
17 km below the surface
Felt
no reports yet
Nearest
Southeast Fairbanks Census Area, 88 km NNE
Nearest mapped fault
Denali fault, 19 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 2013 days ago

A magnitude 1.9 earthquake was recorded 40 km (25 mi) SW of Tok, AK, at 10:01 am AKST on 6 March 2021 (19:01 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 21 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 710,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 500,000× the energy of this one
  3. Around the size people start to feel M 3.0 45× the energy of this one
  4. This earthquake M 1.9 about 21 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 4.2 on 2020-10-26 — about 2,800 times the energy of this one.

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

  1. 5.9 44 km WNW of Mentasta Lake, Alaska · 47 km W of this epicentre
  2. 5.1 3 km ENE of Mentasta Lake, Alaska · 19 km SSW of this epicentre
  3. 5.1 17 km ESE of Mentasta Lake, Alaska · 26 km SSE of this epicentre
  4. 5.0 16 km WNW of Mentasta Lake, Alaska · 27 km WSW 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 63.0888, -143.5741. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Southeast Fairbanks Census Area, AK 88 km (55 mi) NNE earthquakes near Southeast Fairbanks Census Area
Copper River Census Area, AK 119 km (74 mi) S earthquakes near Copper River Census Area

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

Aftershocks so far

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

  1. 1.5 31 km E of Slana, Alaska
  2. 1.5 33 km E of Slana, Alaska
  3. 1.6 15 km WNW of Mentasta Lake, Alaska
  4. 1.7 24 km SSE of Dot Lake Village, Alaska
  5. 1.5 8 km WSW of Mentasta Lake, Alaska
  6. 1.5 18 km S of Tanacross, Alaska
  7. 1.7 29 km E of Slana, Alaska
  8. 1.9 21 km SSW of Tanacross, Alaska
  9. 1.8 22 km SSW of Tanacross, Alaska
  10. 2.9 21 km SSW of Tanacross, Alaska
  11. 1.9 19 km SSW of Tanacross, Alaska
  12. 1.5 13 km SW of Mentasta Lake, Alaska
  13. 1.7 28 km SE of Mentasta Lake, Alaska
  14. 1.5 26 km SE of Mentasta Lake, Alaska
  15. 1.7 27 km SE of Mentasta Lake, 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.