QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1mb_lg

3 km N of Buffalo Gap, South Dakota

· 11 km deep · released about 43 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Custer County 22 kmFall River County 38 kmOglala Lakota County 64 kmPennington County 66 kmDawes County 92 kmLawrence County 100 kmNiobrara County 107 kmWeston County 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 2.1 (mb_lg)
Depth
11 km below the surface
Felt
4 reports · strongest reported intensity III
Nearest
Custer County, 22 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1446 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 4 people have reported feeling it to USGS.

How big was it?

This earthquake released about 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 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.

Where

Epicentre 43.5265, -103.3082. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Custer County, SD 22 km (13 mi) SE of here earthquakes near Custer County
Fall River County, SD 38 km (23 mi) NNE of here earthquakes near Fall River County
Oglala Lakota County, SD 64 km (40 mi) WNW of here earthquakes near Oglala Lakota County
Pennington County, SD 66 km (41 mi) SW of here earthquakes near Pennington County
Dawes County, NE 92 km (57 mi) N of here earthquakes near Dawes County
Lawrence County, SD 100 km (62 mi) SSE of here earthquakes near Lawrence County

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

Aftershocks so far

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

  1. 3.6 7 km W of Fairburn, South Dakota
  2. 2.9 7 km NNE of Buffalo Gap, South Dakota

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.