Kennewick's Seismic Design Category, explained

Kennewick carries Seismic Design Category D under USGS's ASCE 7-16 model. High seismic hazard - this is the category most of coastal California, the Pacific Northwest, and other active fault regions fall into. Code mandates significant seismic detailing and restricts irregular structural configurations. This is the category the Brace + Bolt scope (cripple-wall bracing, foundation bolting) is built for. Nationally, Kennewick ranks above 81% of the 4,875 cities in this dataset for seismic hazard - the 81th percentile.

Kennewick by the numbers

The raw figures: peak ground acceleration 0.185g, short-period spectral response 0.42g, 1-second spectral response 0.159g. Among 125 Washington cities in this dataset, Kennewick ranks 105 for seismic hazard, the 16th percentile within the state. About 86,728 people live in Kennewick, Washington.

Retrofit economics for Kennewick

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for Washington. 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 Kennewick address.

More on how this number was built

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