Does Sidney, MT need an earthquake retrofit?

Under the seismic model IBC and ASCE 7 use for new construction, Sidney is Category A. Lowest seismic design category. Building code requires no seismic-specific detailing here beyond ordinary construction practice. Rank it against the rest of the country and Sidney sits at the 13th percentile for seismic hazard among 4,875 US cities.

How Sidney compares

The raw figures: peak ground acceleration 0.035g, short-period spectral response 0.072g, 1-second spectral response 0.025g. Among 19 Montana cities in this dataset, Sidney ranks 19 for seismic hazard, the 0th percentile within the state. About 6,031 people live in Sidney, Montana.

Retrofit economics for Sidney

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for Montana. A typical retrofit still runs $5,000-$10,000 nationally, about $7,000 for a common single-family job.

Insuring against this, not just retrofitting

Outside California, earthquake coverage is typically sold as an endorsement added to a standard homeowners policy, not a separate product - worth asking about directly when getting a home-insurance quote for a Sidney address.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced Sidney's numbers. The guide to what a Seismic Design Category actually means covers why a category is never a substitute for an engineer's assessment of one specific house.