QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

26 km S of Virginia City, Montana

Yes. A magnitude 2.1 earthquake was recorded 26 km S of Virginia City, Montana, at 11:48 pm MDT on 9 September 2020 (05:48 UTC), 2.0 km deep.

· 2.0 km deep · released about 40 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 30 kmBeaverhead County 76 kmGallatin County 79 kmClark County 91 kmFremont County 100 kmSilver Bow County 109 kmPark County 119 kmJefferson County 119 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
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 2.1 (ml)
Depth
2.0 km below the surface
Felt
no reports yet
Nearest
Madison County, 30 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2252 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 17 km (11 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 40 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 5.8 380,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 270,000× the energy of this one
  3. Around the size people start to feel M 3.0 24× the energy of this one
  4. This earthquake M 2.1 about 40 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 4.3 on 2016-06-13 — about 2,500 times the energy of this one.

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

  1. 6.1 30 km SSW of Big Sky, Montana · 30 km E of this epicentre
  2. 5.2 32 km WNW of Hebgen Lake Estates, Montana · 35 km SE of this epicentre
  3. 5.2 26 km WNW of Hebgen Lake Estates, Montana · 41 km ESE of this epicentre
  4. 5.0 31 km W of Hebgen Lake Estates, Montana · 38 km SE of this epicentre
  5. 5.0 39 km W of Hebgen Lake Estates, Montana · 44 km SSE 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 45.0547, -111.9373. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Madison County, MT 30 km (19 mi) N earthquakes near Madison County
Beaverhead County, MT 76 km (47 mi) W earthquakes near Beaverhead County
Gallatin County, MT 79 km (49 mi) NE earthquakes near Gallatin County
Clark County, ID 91 km (57 mi) SSW earthquakes near Clark County
Fremont County, ID 100 km (62 mi) SSE earthquakes near Fremont County
Silver Bow County, MT 109 km (68 mi) NNW earthquakes near Silver Bow County

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

Aftershocks so far

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

  1. 1.7 43 km W of Hebgen Lake Estates, Montana
  2. 1.6 17 km ESE of Dillon, Montana
  3. 1.5 16 km E of Dillon, Montana
  4. 1.6 17 km ESE of Dillon, Montana
  5. 1.9 12 km NNW of Ennis, Montana
  6. 1.8 28 km SSE of Virginia City, Montana
  7. 1.6 28 km S of Ennis, Montana
  8. 1.8 28 km SSE of Virginia City, Montana
  9. 2.5 23 km SE of Virginia City, Montana
  10. 2.2 12 km NNW of Ennis, Montana
  11. 2.7 30 km W of Hebgen Lake Estates, Montana
  12. 1.5 38 km WNW of Hebgen Lake Estates, Montana
  13. 1.5 7 km WSW of Ennis, Montana
  14. 1.6 13 km NNW of Ennis, Montana
  15. 2.1 13 km NNW of Ennis, Montana

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.