QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0ml

4 km E of Mentasta Lake, Alaska

Yes. A magnitude 4.0 earthquake was recorded 4 km E of Mentasta Lake, Alaska, at 11:01 pm AKDT on 9 October 2019 (07:01 UTC), 7.3 km deep. 9 people have reported feeling it to USGS.

· 7.3 km deep · released about 15 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Copper River Census Area 99 kmSoutheast Fairbanks Census Area 108 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 4.0 (ml)
Depth
7.3 km below the surface
Felt
9 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Nearest
Copper River Census Area, 99 km S
Nearest mapped fault
Denali fault, 1 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 2512 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 97 km (60 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 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 32× 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 (31 mi) since our catalogue begins in 2016. No other earthquake of M4 or more has been recorded this close in that time.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 5.9 44 km WNW of Mentasta Lake, Alaska · 49 km WNW of this epicentre
  2. 5.4 45 km WNW of Mentasta Lake, Alaska · 49 km WNW of this epicentre
  3. 5.1 3 km ENE of Mentasta Lake, Alaska · 2 km NW of this epicentre
  4. 5.1 17 km ESE of Mentasta Lake, Alaska · 13 km ESE of this epicentre
  5. 5.0 16 km WNW of Mentasta Lake, Alaska · 21 km WNW 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 62.9163, -143.6808. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Copper River Census Area, AK 99 km (61 mi) S earthquakes near Copper River Census Area
Southeast Fairbanks Census Area, AK 108 km (67 mi) NNE earthquakes near Southeast Fairbanks Census Area

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

Aftershocks so far

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

  1. 2.1 6 km ESE of Mentasta Lake, Alaska
  2. 1.6 17 km SE of Mentasta Lake, Alaska
  3. 3.4 28 km E of Slana, Alaska
  4. 2.5 30 km ESE of Slana, Alaska
  5. 1.5 31 km E of Slana, Alaska
  6. 1.8 29 km ESE of Slana, Alaska
  7. 1.6 15 km NNW of Mentasta Lake, Alaska
  8. 2.2 14 km SSE of Mentasta Lake, Alaska
  9. 1.9 30 km E of Slana, Alaska
  10. 2.2 19 km WNW of Mentasta Lake, Alaska
  11. 1.7 14 km WSW of Mentasta Lake, Alaska
  12. 2.3 24 km WNW of Mentasta Lake, Alaska
  13. 1.7 8 km SE of Mentasta Lake, Alaska
  14. 1.7 9 km SSE of Mentasta Lake, Alaska
  15. 1.9 30 km NNW of Nabesna, 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.