Earthquake · reviewed by a seismologist
M 1.7ml
Earthquake near Helena, MT
No earthquake was likely felt in Helena in the 24 hours to 7:15 am MST (14:15 UTC). The last one was M 1.6, 7 km (4 mi) SE, at 11:34 am MDT on 14 October 2026, estimated intensity II (weak) in town. Every earthquake near Helena
This page: a magnitude 1.7 earthquake was recorded 25 km (16 mi) east of Helena, MT, at 9:15 pm MDT on 21 June 2025 (03:15 UTC), 13 km deep.
USGS: 14 km NNW of Winston, Montana
- When
- 9:15 pm MDT on 21 June 2025 ()
- Where
- 25 km (16 mi) east of Helena, MT · earthquakes near Helena
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 1.7 (ml)
- Depth
- 13 km below the surface
- Felt
- no reports yet
- Nearest
- Broadwater County, 34 km SSE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 507 days ago
Earthquake alerts for Helena, MT
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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 it was probably too small to be felt, even directly above it. In Helena, 25 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.
Earthquakes near other towns within 30 km: East Helena, Helena Valley Southeast, Montana City, Helena Valley Northeast, Clancy, Helena Valley West Central.
How big was it?
This earthquake released about 9.3 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.
- Mineral, Virginia 2011 M 5.8 1,600,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
- Around the size people start to feel M 3.0 100× the energy of this one
- This earthquake M 1.7 about 9.3 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 4 earthquakes of M5 or more within 50 km:
- 6.1 The 1935 Helena, Montana Earthquakes (Mainshock) · 5 km ESE of this epicentre
- 5.9 2 km ENE of Helena, Montana · 22 km W of this epicentre
- 5.9 The 1935 Helena, Montana Earthquakes (Largest Aftershock) · 13 km WSW of this epicentre
- 5.0 2 km ENE of Helena, Montana · 22 km W 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 46.6023, -111.7085. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Broadwater County, MT | 34 km (21 mi) | SSE | earthquakes near Broadwater County |
| Jefferson County, MT | 60 km (37 mi) | SSW | earthquakes near Jefferson County |
| Meagher County, MT | 60 km (37 mi) | E | earthquakes near Meagher County |
| Lewis and Clark County, MT | 77 km (48 mi) | NW | earthquakes near Lewis and Clark County |
| Cascade County, MT | 84 km (52 mi) | NNE | earthquakes near Cascade County |
| Powell County, MT | 97 km (60 mi) | WNW | earthquakes near Powell County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
43 earthquakes have been recorded within 50 km since this one.
- 1.5 8 km WSW of Townsend, Montana
- 0.8 10 km NW of Helena Valley Northwest, Montana
- 1.1 14 km NNE of Marysville, Montana
- 1.3 20 km NNE of Marysville, Montana
- 1.2 18 km E of Townsend, Montana
- 1.7 8 km W of Townsend, Montana
- 1.6 2 km SE of South Hills, Montana
- 1.5 8 km W of Townsend, Montana
- 1.5 16 km NE of Helena Valley Northwest, Montana
- 1.6 14 km SSE of Craig, Montana
- 1.7 8 km W of Townsend, Montana
- 2.4 21 km SSE of Craig, Montana
- 1.6 9 km W of Townsend, Montana
- 1.5 9 km WSW of Townsend, Montana
- 1.5 1 km SSE of South Hills, 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.