QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

9 km SE of Mentasta Lake, Alaska

· 3.5 km deep · released about 5.4 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Copper River Census Area 94 kmSoutheast Fairbanks Census Area 113 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 1.5 (ml)
Depth
3.5 km below the surface
Felt
no reports yet
Nearest
Copper River Census Area, 94 km S
Nearest mapped fault
Totschunda fault, 2 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 1256 days ago

A magnitude 1.5 earthquake was recorded 9 km SE of Mentasta Lake, Alaska at 20:54 UTC on 2023-04-21. This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 5.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 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 11,000 times the energy of this one.

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

  1. 5.1 3 km ENE of Mentasta Lake, Alaska · 8 km NNW of this epicentre
  2. 5.1 17 km ESE of Mentasta Lake, Alaska · 9 km E of this epicentre
  3. 5.0 16 km WNW of Mentasta Lake, Alaska · 25 km WNW of this epicentre
  4. 5.0 21 km N of Nabesna, Alaska · 49 km SE 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 62.8651, -143.6382. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Copper River Census Area, AK 94 km (58 mi) S earthquakes near Copper River Census Area
Southeast Fairbanks Census Area, AK 113 km (70 mi) N earthquakes near Southeast Fairbanks Census Area

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

Aftershocks so far

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

  1. 1.6 7 km NE of Slana, Alaska
  2. 3.0 13 km ENE of Slana, Alaska
  3. 2.3 13 km SE of Mentasta Lake, Alaska
  4. 3.1 13 km N of Mentasta Lake, Alaska
  5. 1.5 14 km SE of Mentasta Lake, Alaska
  6. 1.7 13 km E of Slana, Alaska
  7. 1.8 26 km E of Slana, Alaska
  8. 1.8 24 km SE of Mentasta Lake, Alaska
  9. 1.7 26 km SSW of Tanacross, Alaska
  10. 2.2 22 km SW of Tanacross, Alaska
  11. 1.6 25 km SSW of Tanacross, Alaska
  12. 2.2 24 km SW of Tanacross, Alaska
  13. 1.6 27 km E of Slana, Alaska
  14. 2.0 27 km NNW of Nabesna, Alaska
  15. 1.8 7 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.