Caruthersville's Seismic Design Category, explained

Caruthersville clears the point where the standard Seismic Design Category tables stop applying - USGS returns no letter here, only a flag that a site-specific study (ASCE 7-16 §11.4.8) is required. Treat that as more severe than any lettered category, not as missing data. Rank it against the rest of the country and Caruthersville sits at the 100th percentile for seismic hazard among 4,875 US cities.

Caruthersville by the numbers

The raw figures: peak ground acceleration 1.741g, short-period spectral response 2.763g, 1-second spectral response 1.05g. Among 135 Missouri cities in this dataset, Caruthersville ranks 1 for seismic hazard, the 100th percentile within the state. About 5,170 people live in Caruthersville, Missouri.

Retrofit economics for Caruthersville

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

More on how this number was built

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