Significant earthquakes of 1935

October 31, 1935 Earthquake: Helena, Montana, United States

October 31, 1935 · M6 · 2 deaths · $6 million

A magnitude 6 earthquake struck Helena, Montana, United States on October 31, 1935 at 18:37:47 UTC. It killed 2 people.

Map

Where it struck, with the other significant earthquakes within 200 km. Circles are sized and colored by magnitude; select one for its page.

The earthquake

Date
October 31, 1935
Time
18:37:47 UTC
Place
Helena, Montana, United States
Magnitude
6 (Ms)
Intensity
8 on the Modified Mercalli scale
Tsunami
None recorded
Epicenter
46.600° N, 112.000° W

The toll

Deaths
2
Damage
$6 million

Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.

What the record says

NCEI’s account, from the sources it cites.

This aftershock was almost as severe as the main tremor on Oct. 19. Two people were killed at Helena, and about $1 million in property damage occurred, bringing the death toll from this series to four and the damage total to $4 million. It intensified the damage in all the towns and damaged structures weakened by previous shocks. Most residents described it as sharper and more pronounced than the main earthquake on Oct 19. (Reference #542)

Reference #1250 lists $6 million damage.

Photos

From the NCEI/WDS Natural Hazards Image Database (doi:10.7289/V5154F01). Only photos by the USGS and NOAA, which are public domain, are shown.

Damage to Helena, MT High School
Damage to Helena, MT High School The photo shows the west wing of Helena High School that collapsed in the October 31 earthquake. The collapsed part of the school had reinforced concrete frame, floors, and roof, and the tile floors were faced with brick. The greatest amount of damage to a single structure was incurred by this building although it had just been completed only two months… Photo: NOAA National Geophysical Data Center.

Other significant earthquakes nearby

Within 200 km, the deadliest first.

More

Significant earthquakes of 1935The 1900sEvery quake the USGS located in 1935Recent earthquakes near hereThis day in weather history

Sources

Significant earthquakes from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-09-24. NCEI earthquake 3563.