Earthquake · reviewed by a seismologist
M 1.8ml
55 km SW of Lima, Montana
Yes. A magnitude 1.8 earthquake was recorded 55 km SW of Lima, Montana, at 7:56 am MDT on 24 August 2020 (13:56 UTC), 9.6 km deep.
- When
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 1.8 (ml)
- Depth
- 9.6 km below the surface
- Felt
- no reports yet
- Nearest
- Clark County, 53 km E
- Nearest mapped fault
- Beaverhead fault, 8 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 2267 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 10 km (6 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 17 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 900,000× the energy of this one
- Magna, Utah 2020 M 5.7 640,000× the energy of this one
- Around the size people start to feel M 3.0 57× the energy of this one
- This earthquake M 1.8 about 17 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 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 44.2430, -113.0122. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Clark County, ID | 53 km (33 mi) | E | earthquakes near Clark County |
| Butte County, ID | 63 km (39 mi) | SSW | earthquakes near Butte County |
| Jefferson County, ID | 74 km (46 mi) | SE | earthquakes near Jefferson County |
| Custer County, ID | 99 km (61 mi) | W | earthquakes near Custer County |
| Beaverhead County, MT | 100 km (62 mi) | N | earthquakes near Beaverhead County |
| Lemhi County, ID | 103 km (64 mi) | NW | earthquakes near Lemhi County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
12 earthquakes have been recorded within 50 km since this one.
- 1.5 21 km SSW of Lima, Montana
- 2.0 30 km W of Lima, Montana
- 2.3 15 km SW of Lima, Montana
- 1.5 15 km SW of Lima, Montana
- 1.8 Idaho-Montana border region
- 1.6 22 km WSW of Lima, Montana
- 2.4 21 km WSW of Lima, Montana
- 3.1 32 km S of Lima, Montana
- 1.5 17 km SSW of Lima, Montana
- 2.5 21 km SW of Lima, Montana
- 2.0 26 km SE of Leadore, Idaho
- 1.6 27 km SW of Lima, 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.