Earthquake · reviewed by a seismologist
M 2.5ml
Earthquake near Polson, MT
USGS: 2 km SSW of Elmo, Montana
- When
- 12:37 pm MDT on 28 May 2017 ()
- Where
- 19 km (12 mi) NW of Polson, MT · earthquakes near Polson
- Magnitude
- M 2.5 (ml)
- Depth
- 5.0 km below the surface
- Felt
- 4 reports · strongest reported intensity III
- Nearest
- Lake County, 27 km SE
- Nearest mapped fault
- Mission fault, 15 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 3336 days ago
A magnitude 2.5 earthquake was recorded 19 km (12 mi) NW of Polson, MT, at 12:37 pm MDT on 28 May 2017 (18:37 UTC). 4 people have reported feeling it to USGS. This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
Earthquakes near other towns within 30 km: Lakeside, Pablo.
How big was it?
This earthquake released about 170 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 89,000× the energy of this one
- Magna, Utah 2020 M 5.7 63,000× the energy of this one
- Around the size people start to feel M 3.0 5.6× the energy of this one
- This earthquake M 2.5 about 170 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:
- 5.5 Western Montana · 47 km ENE 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 47.8065, -114.3568. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lake County, MT | 27 km (17 mi) | SE | earthquakes near Lake County |
| Flathead County, MT | 59 km (37 mi) | NNE | earthquakes near Flathead County |
| Sanders County, MT | 62 km (38 mi) | W | earthquakes near Sanders County |
| Mineral County, MT | 93 km (58 mi) | SW | earthquakes near Mineral County |
| Missoula County, MT | 93 km (58 mi) | SSE | earthquakes near Missoula County |
| Lincoln County, MT | 117 km (72 mi) | NW | earthquakes near Lincoln 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.
- 2.5 18 km WNW of Dixon, Montana
- 2.9 4 km N of Elmo, Montana
- 2.5 6 km WNW of Bear Dance, Montana
- 1.9 1 km W of Charlo, Montana
- 2.2 8 km WNW of Niarada, Montana
- 1.6 4 km ESE of Rollins, Montana
- 1.5 11 km WNW of Condon, Montana
- 1.7 3 km E of Forest Hill Village, Montana
- 2.5 2 km WSW of Bear Dance, Montana
- 1.9 4 km NE of Bear Dance, Montana
- 1.6 8 km NNE of Paradise, Montana
- 1.9 11 km SE of Hot Springs, Montana
- 1.8 13 km E of Pablo, Montana
- 2.0 6 km ESE of Bear Dance, Montana
- 1.5 18 km E of Finley Point, 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.