Earthquake · reviewed by a seismologist
M 2.4ml
Earthquake near Helena Valley Northeast, MT
No earthquake was likely felt in Helena Valley Northeast in the 24 hours to 5:45 pm MST (00:45 UTC). The last one was M 2.7, 11 km (7 mi) SSW, at 3:38 pm MDT on 9 March 2025, estimated intensity III (weak) in town; 267 felt reports to USGS. Every earthquake near Helena Valley Northeast
This page: a magnitude 2.4 earthquake was recorded 4 km (3 mi) north-northwest of Helena Valley Northeast, MT, at 9:23 am MDT on 25 October 2020 (15:23 UTC), less than 1 km deep.
USGS: 4 km NNW of Helena Valley Northeast, Montana
- When
- 9:23 am MDT on 25 October 2020 ()
- Where
- 4 km (3 mi) north-northwest of Helena Valley Northeast, MT · earthquakes near Helena Valley Northeast
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 2.4 (ml)
- Depth
- -2.1 km below the surface
- Felt
- no reports yet
- Nearest
- Lewis and Clark County, 53 km NW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2207 days ago
Earthquake alerts for Helena Valley Northeast, MT
Get a notification in this browser when USGS records an earthquake near Helena Valley Northeast, MT. No account or email needed.
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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 21 km (13 mi) from the epicentre. In Helena Valley Northeast, 4 km away, the estimate is intensity III (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.
Likely felt in: Helena 17 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 100 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 140,000× the energy of this one
- Magna, Utah 2020 M 5.7 100,000× the energy of this one
- Around the size people start to feel M 3.0 9.1× the energy of this one
- This earthquake M 2.4 about 100 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
The largest earthquake within 50 km since 2016 was M 4.3 on 2016-01-30 — about 900 times the energy of this one.
Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:
- 6.1 The 1935 Helena, Montana Earthquakes (Mainshock) · 29 km SE of this epicentre
- 5.9 2 km ENE of Helena, Montana · 15 km S of this epicentre
- 5.9 The 1935 Helena, Montana Earthquakes (Largest Aftershock) · 23 km SSE of this epicentre
- 5.0 2 km ENE of Helena, Montana · 15 km S 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 46.7370, -111.9642. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lewis and Clark County, MT | 53 km (33 mi) | NW | earthquakes near Lewis and Clark County |
| Broadwater County, MT | 58 km (36 mi) | SE | earthquakes near Broadwater County |
| Jefferson County, MT | 69 km (43 mi) | S | earthquakes near Jefferson County |
| Powell County, MT | 75 km (46 mi) | W | earthquakes near Powell County |
| Cascade County, MT | 79 km (49 mi) | NE | earthquakes near Cascade County |
| Meagher County, MT | 81 km (51 mi) | ESE | earthquakes near Meagher County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
35 earthquakes have been recorded within 50 km since this one.
- 1.5 15 km ESE of Lincoln, Montana
- 1.7 14 km ESE of Lincoln, Montana
- 1.5 14 km ESE of Lincoln, Montana
- 1.7 2 km NNW of Montana City, Montana
- 2.2 6 km W of Helena Valley West Central, Montana
- 2.4 8 km NNE of Helena Valley Northwest, Montana
- 1.5 15 km SE of Lincoln, Montana
- 2.0 14 km ESE of Lincoln, Montana
- 2.9 11 km SW of Winston, Montana
- 2.2 14 km ESE of Lincoln, Montana
- 1.6 15 km SE of Lincoln, Montana
- 1.8 13 km ESE of Lincoln, Montana
- 1.7 15 km NW of Marysville, Montana
- 1.9 14 km ESE of Lincoln, Montana
- 1.7 15 km ESE of Lincoln, 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.