QuakeIndex

mine collapse · reviewed by a seismologist

M 4.3mw

Earthquake near Fairfield Glade, TN

No earthquake was likely felt in Fairfield Glade in the 24 hours to 2:29 am CST (08:29 UTC). The last one was M 4.1, 96 km (59 mi) ESE, at 8:04 am CDT on 10 May 2025, estimated intensity III (weak) in town; 45,935 felt reports to USGS. Every earthquake near Fairfield Glade

No: USGS classifies this as a mine collapse, not an earthquake. A magnitude 4.3 mine collapse was recorded 10 km (6 mi) south-southeast of Fairfield Glade, TN, at 6:57 am CDT on 13 August 2021 (11:57 UTC), less than 1 km deep. 1 person has reported feeling it to USGS.

USGS: 2 km ENE of Crab Orchard, Tennessee

82 km (51 mi) W of Knoxville, TN

6:57 am CDT, Aug 13, 2021 · · 0.2 km deep · released about 43 tons of TNT

Every earthquake near Fairfield Glade Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Cumberland County 13 kmRoane County 31 kmMorgan County 31 kmRhea County 36 kmMeigs County 45 kmBledsoe County 48 kmFentress County 51 kmLoudon County 53 kmWhite County 54 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
6:57 am CDT on 13 August 2021 ()
Where
10 km (6 mi) south-southeast of Fairfield Glade, TN · earthquakes near Fairfield Glade
Magnitude
M 4.3 (mw)
Depth
0.2 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Cumberland County, 13 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1839 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 550 km (342 mi) from the epicentre. In Fairfield Glade, 10 km away, the estimate is intensity V (moderate). 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.

Likely felt in: Decatur 45 km, intensity IV. Estimated for each town centre; each link is that town's own record.

USGS catalogues this as mine collapse, not an earthquake.

How big was it?

This earthquake released about 43 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 4,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 180× the energy of this one
  3. Magna, Utah 2020 M 5.7 130× the energy of this one
  4. This earthquake M 4.3 about 43 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 89× 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 4.4 on 2018-12-12 — about 1.4 times the energy of this one.

Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.

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 35.9163, -84.8532. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Cumberland County, TN 13 km (8 mi) WNW earthquakes near Cumberland County
Roane County, TN 31 km (19 mi) ESE earthquakes near Roane County
Morgan County, TN 31 km (19 mi) NE earthquakes near Morgan County
Rhea County, TN 36 km (22 mi) SSW earthquakes near Rhea County
Meigs County, TN 45 km (28 mi) S earthquakes near Meigs County
Bledsoe County, TN 48 km (30 mi) SW earthquakes near Bledsoe County

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

Aftershocks so far

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

  1. 2.2 10 km WNW of Philadelphia, Tennessee
  2. 2.2 10 km WNW of Philadelphia, Tennessee
  3. 2.2 2 km W of Dayton, Tennessee
  4. 2.1 4 km NNW of Dayton, Tennessee
  5. 2.2 13 km S of Midtown, Tennessee
  6. 1.6 9 km SW of Spring City, Tennessee
  7. 1.8 5 km NNE of Niota, Tennessee
  8. 1.8 4 km WSW of Decatur, Tennessee
  9. 2.0 10 km NNW of Dayton, Tennessee
  10. 1.9 10 km S of Spring City, Tennessee
  11. 2.5 9 km WSW of Oakdale, Tennessee
  12. 2.0 1 km ENE of Dayton, Tennessee
  13. 1.8 4 km SW of Sweetwater, Tennessee
  14. 1.5 6 km NNW of Philadelphia, Tennessee
  15. 1.9 15 km WNW of Sweetwater, Tennessee

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.