U.S. state profile · USGS ComCat
Earthquakes in Montana
Montana has catalogued 28 M4+ earthquakes since 2005 (ranked 15th of 39 U.S. states), with the strongest reaching magnitude M7.2.
Montana ranks 15th of 39 U.S. states and territories by catalogued seismic activity - a state with limited seismic activity, averaging about 1 M4+ events a year alongside 4 significant M6+ earthquakes since 1900. Below: the full M6+ event history, magnitude and depth profile, and yearly trend.
- 28
- M4+ events (since 2005)
- 4
- Major M6+ (since 1900)
- M7.2
- Strongest
- ~1
- M4+ per year
The verdict
Montana is moderately seismically active, above the global median, with 28 M4+ earthquakes logged since 2005 and 4 major M6+ events since 1900, the strongest reaching magnitude 7.2.
- 1925
- busiest year (1 major events)
- 11 km
- average recorded event depth
- 100%
- of events are shallow (<70 km, the most damaging kind)
Average catalogued magnitude is 4.3 - most events are moderate tremors felt but rarely damaging. On the M4+ activity ladder New Mexico sits immediately above at 37 events and Utah sits immediately below at 25.
USGS ComCat event tape
Event tape MT · Montana M4+ · 15th/39
Montana · 28 M4+ · max M7.2 · 4 M6+
- BUSY 28
- SHAL 15th/39
- PCT M7.2
- VS-PEER 4
- COMCAT near New Mexico
- TAPE 100% shallow
Stamps derive from this jurisdiction's USGS ComCat row (M4+ book, rank, peak magnitude, M6+ record, ladder neighbour, depth/peak year), not a hazard forecast. PlainQuake is informational only - not professional advice and not a substitute for official USGS guidance. See our disclaimer. Verify with USGS ComCat → · Read with methodology → · How earthquakes are measured → · Most active U.S. regions → · All state catalog rows → · States ranked →
Observed impact record
What ComCat observed after earthquakes in Montana
USGS recorded Modified Mercalli Intensity (MMI) for 2 events in this catalogued record; their average observed intensity was MMI 8.5. These are only events with an observation, not an estimate of future shaking or a safety rating.
- MMI observations
- 2
- Average observed MMI
- 8.5
- PAGER alerts / tsunami flags
- 0 / 0
Source: USGS Comprehensive Earthquake Catalog (ComCat) GeoJSON impact fields. Missing MMI, alert, and tsunami values remain unreported rather than being treated as zero.
Where Montana sits in the catalog
Rank 15th of 39 tracked U.S. states and territories (62th percentile by M4+ count since 2005). On the M4+ activity ladder New Mexico sits immediately above at 37 events and Utah sits immediately below at 25.
- New Mexico - next more active (37 M4+)
- Utah - next less active (25 M4+)
Montana's M4+ count vs. every tracked state
Total catalogued M4+ events since 2005, USGS ComCat
28 Top 38% higher than 62% of 39 states
Each bar is a 100-wide band; taller bars hold more states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source USGS Comprehensive Earthquake Catalog (ComCat) · 2005-present
Major (M6+) earthquakes in Montana by year
Count of significant (magnitude 6.0+) events catalogued each year
- 1925
1925: 1 major (M6+) events
1
- 1935
1935: 1 major (M6+) events
1
- 1947
1947: 1 major (M6+) events
1
- 1959
1959: 1 major (M6+) events
1
What this shows Montana's most active year for major earthquakes was 1925 (1 M6+ events). Major-quake counts track the episodic release of tectonic stress, not a smooth trend.
Magnitude distribution of major events
Breakdown of the 4 significant (M6+) earthquakes on record for Montana.
M7.0–7.9
1
25.0%
M6.0–6.9
3
75.0%
Depth of major earthquakes
Hypocentral depth of the 4 M6+ events, shallow quakes shake the surface hardest. Average depth: 11 km.
Shallow (<70 km)
4
100% of events
Intermediate (70–300 km)
0
0.0% of events
Deep (>300 km)
0
0.0% of events
Seismic hazard context
Catalogued counts on this page are history, not a building-code hazard map. Montana's latest M4+ catalog entry is dated Jan 29, 2026. For the national PGA design-basis tiers, see the seismic risk maps guide or the USGS National Seismic Hazard Model.
Strongest earthquakes in Montana
The 4 most powerful events on record (USGS, since 1900).
| Mag | Location | Depth | Date |
|---|---|---|---|
| 7.2 | The 1959 Hebgen Lake, Montana Earthquake | 12.0 km | Aug 18, 1959 |
| 6.6 | The 1925 Clarkston Valley, Montana Earthquake | 0.0 km | Jun 28, 1925 |
| 6.1 | 12 km N of Winston, Montana | 15.0 km | Oct 19, 1935 |
| 6.1 | 30 km SSW of Big Sky, Montana | 15.0 km | Nov 23, 1947 |
Significant earthquake record (4 events)
Every catalogued magnitude-6.0-and-above earthquake in Montana since 1900, most recent first.
| Mag | Location | Depth | Date |
|---|---|---|---|
| 7.2 | The 1959 Hebgen Lake, Montana Earthquake | 12.0 km | Aug 18, 1959 |
| 6.1 | 30 km SSW of Big Sky, Montana | 15.0 km | Nov 23, 1947 |
| 6.1 | 12 km N of Winston, Montana | 15.0 km | Oct 19, 1935 |
| 6.6 | The 1925 Clarkston Valley, Montana Earthquake | 0.0 km | Jun 28, 1925 |
Peak-magnitude sample from the same roster
A Montana-keyed shuffle of states with a recorded max magnitude. Layout order flips by state so sibling pages do not open the same block first.
Other states in this catalog sample
A second Montana-keyed shuffle of the full 38-state roster (not ABS-gap nearest neighbors).
According to the US Geological Survey Earthquake Hazards Program, PlainQuake's figures are rendered directly from 317,293 recorded M4+ earthquakes and 14,444 significant M6+ events (USGS ComCat, 2005-present) -- no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-08-26.