QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9ml

34 km E of Tanana, Alaska

Yes. A magnitude 3.9 earthquake was recorded 34 km E of Tanana, Alaska at 19:11 UTC on 2018-09-16, 16 km deep. 2 people have reported feeling it to USGS.

· 16 km deep · released about 11 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Yukon-Koyukuk Census Area 27 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 3.9 (ml)
Depth
16 km below the surface
Felt
2 reports · strongest reported intensity II
Measured shaking
intensity IV (ShakeMap)
Nearest
Yukon-Koyukuk Census Area, 27 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1185 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 88 km (55 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 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 16,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
  3. Magna, Utah 2020 M 5.7 500× the energy of this one
  4. This earthquake M 3.9 about 11 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 22× 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 since 2016 was M 4.2 on 2016-05-18 — about 2.8 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 5.9 15 km SSE of Tanana, Alaska · 30 km WSW of this epicentre
  2. 5.9 31 km SSE of Tanana, Alaska · 39 km SW 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 65.1562, -151.3493. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Yukon-Koyukuk Census Area, AK 27 km (17 mi) NNW earthquakes near Yukon-Koyukuk Census Area

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

Aftershocks so far

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

  1. 1.6 33 km SE of Tanana, Alaska
  2. 2.2 Central Alaska
  3. 1.6 39 km WSW of Manley Hot Springs, Alaska
  4. 2.0 9 km WSW of Manley Hot Springs, Alaska
  5. 1.8 37 km WSW of Manley Hot Springs, Alaska
  6. 1.9 28 km SSW of Manley Hot Springs, Alaska
  7. 1.6 15 km E of Tanana, Alaska
  8. 1.7 31 km ENE of Tanana, Alaska
  9. 1.8 11 km NW of Manley Hot Springs, Alaska
  10. 1.6 15 km ESE of Tanana, Alaska
  11. 1.7 31 km SSE of Tanana, Alaska
  12. 1.8 53 km SW of Manley Hot Springs, Alaska
  13. 1.9 47 km SSE of Tanana, Alaska
  14. 2.2 29 km NW of Manley Hot Springs, Alaska
  15. 1.5 35 km SSE of Tanana, 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.