QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7ml

6 km E of Lima, Montana

Yes. A magnitude 1.7 earthquake was recorded 6 km E of Lima, Montana, at 12:03 pm MST on 26 January 2021 (19:03 UTC), 2.0 km deep.

· 2.0 km deep · released about 10 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Clark County 41 kmBeaverhead County 63 kmMadison County 89 kmFremont County 94 kmJefferson County 95 kmLemhi County 114 kmMadison County 116 kmButte 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 1.7 (ml)
Depth
2.0 km below the surface
Felt
no reports yet
Nearest
Clark County, 41 km SSE
Nearest mapped fault
Red Rock fault, 9 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 2115 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 12 km (7 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 10 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 92× the energy of this one
  4. This earthquake M 1.7 about 10 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 4.6 on 2019-04-09 — about 23,000 times the energy of this one.

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

  1. 5.1 19 km NW of Lima, Montana · 24 km NW of this epicentre
  2. 5.1 22 km NW of Lima, Montana · 28 km NW 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 44.6393, -112.5045. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Clark County, ID 41 km (25 mi) SSE earthquakes near Clark County
Beaverhead County, MT 63 km (39 mi) NNW earthquakes near Beaverhead County
Madison County, MT 89 km (55 mi) NNE earthquakes near Madison County
Fremont County, ID 94 km (58 mi) ESE earthquakes near Fremont County
Jefferson County, ID 95 km (59 mi) S earthquakes near Jefferson County
Lemhi County, ID 114 km (71 mi) WNW earthquakes near Lemhi County

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

Aftershocks so far

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

  1. 1.5 17 km SSW of Lima, Montana
  2. 1.7 29 km SSW of Dillon, Montana
  3. 2.4 25 km N of Spencer, Idaho
  4. 1.5 38 km SSW of Virginia City, Montana
  5. 2.2 35 km NNE of Spencer, Idaho
  6. 1.5 37 km SSW of Dillon, Montana
  7. 2.5 21 km SW of Lima, Montana
  8. 2.0 36 km NNE of Spencer, Idaho
  9. 1.6 3 km ENE of Lima, Montana
  10. 2.6 16 km NE of Lima, Montana
  11. 1.8 46 km NNE of Spencer, Idaho

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.