Does Boulder, CO need an earthquake retrofit?

Under the seismic model IBC and ASCE 7 use for new construction, Boulder is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. Rank it against the rest of the country and Boulder sits at the 60th percentile for seismic hazard among 4,875 US cities.

Boulder by the numbers

The raw figures: peak ground acceleration 0.131g, short-period spectral response 0.236g, 1-second spectral response 0.062g. Among 79 Colorado cities in this dataset, Boulder ranks 21 for seismic hazard, the 74th percentile within the state. About 106,803 people live in Boulder, Colorado.

Bracing and bolting: the actual cost

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

What this means for insurance

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 Boulder address.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced Boulder'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.