Does Sioux Falls, SD need an earthquake retrofit?

Sioux Falls carries Seismic Design Category A under USGS's ASCE 7-16 model. 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 Sioux Falls sits at the 14th percentile for seismic hazard among 4,875 US cities.

How Sioux Falls compares

USGS's underlying values for Sioux Falls: 0.045g peak ground acceleration, 0.091g at short period, 0.035g at 1 second. Within South Dakota alone, Sioux Falls ranks 13 of 18 cities by seismic hazard - the 29th percentile in-state. Sioux Falls has a population of about 209,289.

Retrofit economics for Sioux Falls

A full earthquake retrofit typically runs $5,000-$10,000 nationally (around $7,000 typical), driven mainly by house size and foundation type, not by South Dakota specifically. California's Earthquake Brace + Bolt grant, which covers a large share of this cost, is a California-only program and does not apply in South Dakota.

Earthquake insurance for a Sioux Falls home

A Sioux Falls homeowner cannot buy a standalone earthquake policy in most cases - it is added to an existing homeowners policy as an endorsement, so the place to start is a regular home-insurance quote.

Where Sioux Falls's figures come from

Sioux Falls's Category A and every number above trace to USGS's own ASCE 7-16 Design Maps service - see the methodology guide. See the category explainer for what Category A does and doesn't tell you about Sioux Falls.