QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

23 km SE of White Sulphur Springs, Montana

Yes. A magnitude 1.9 earthquake was recorded 23 km SE of White Sulphur Springs, Montana, at 2:15 am MDT on 1 April 2018 (08:15 UTC), 9.7 km deep.

· 9.7 km deep · released about 21 lb of TNT

10 km30 km60 km120 km N Meagher County 28 kmBroadwater County 60 kmWheatland County 67 kmJudith Basin County 79 kmSweet Grass County 87 kmGallatin County 102 kmPark County 103 kmJefferson County 107 kmCascade County 115 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 1.9 (ml)
Depth
9.7 km below the surface
Felt
no reports yet
Nearest
Meagher County, 28 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3145 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 11 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 21 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 730,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 520,000× the energy of this one
  3. Around the size people start to feel M 3.0 46× the energy of this one
  4. This earthquake M 1.9 about 21 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.4 Clarkston Valley, Montana (Aftershock) · 48 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 46.3780, -110.7168. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Meagher County, MT 28 km (17 mi) NW earthquakes near Meagher County
Broadwater County, MT 60 km (37 mi) W earthquakes near Broadwater County
Wheatland County, MT 67 km (42 mi) ENE earthquakes near Wheatland County
Judith Basin County, MT 79 km (49 mi) NNE earthquakes near Judith Basin County
Sweet Grass County, MT 87 km (54 mi) SE earthquakes near Sweet Grass County
Gallatin County, MT 102 km (63 mi) SSW earthquakes near Gallatin County

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

Aftershocks so far

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

  1. 1.7 29 km N of Sedan, Montana
  2. 1.8 23 km ENE of Wilsall, Montana
  3. 2.2 30 km ENE of Wilsall, 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.