Earthquake · reviewed by a seismologist
M 1.8ml
Earthquake near Eureka, MT
No earthquake was likely felt in Eureka in the 24 hours to 2:20 pm MST (21:20 UTC). The last one was M 3.2, 39 km (24 mi) ESE, at 12:58 am MST on 3 January 2021, estimated intensity II (weak) in town. Every earthquake near Eureka
This page: a magnitude 1.8 earthquake was recorded 36 km (22 mi) northwest of Eureka, MT, at 11:44 am MDT on 22 October 2021 (17:44 UTC), 3.5 km deep.
USGS: 20 km NW of West Kootenai, Montana
- When
- 11:44 am MDT on 22 October 2021 ()
- Where
- 36 km (22 mi) northwest of Eureka, MT · earthquakes near Eureka
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 1.8 (ml)
- Depth
- 3.5 km below the surface
- Felt
- no reports yet
- Nearest
- Lincoln County, 61 km S
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1843 days ago
Earthquake alerts for Eureka, MT
Get a notification in this browser when USGS records an earthquake near Eureka, MT. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 13 km (8 mi) from the epicentre. In Eureka, 36 km away, the estimate is intensity II (weak). 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 16 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 5.8 930,000× the energy of this one
- Magna, Utah 2020 M 5.7 660,000× the energy of this one
- Around the size people start to feel M 3.0 59× the energy of this one
- This earthquake M 1.8 about 16 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 49.0973, -115.4192. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lincoln County, MT | 61 km (38 mi) | S | earthquakes near Lincoln County |
| Boundary County, ID | 88 km (55 mi) | WSW | earthquakes near Boundary County |
| Bonner County, ID | 123 km (77 mi) | SW | earthquakes near Bonner County |
| Flathead County, MT | 134 km (83 mi) | SE | earthquakes near Flathead County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
No further earthquakes have been recorded within 50 km since this one.
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.