Surprise's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Surprise is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Surprise in the 53th percentile nationally for seismic hazard - higher than 53% of the 4,875 US cities USGS was checked against here.

How Surprise compares

USGS's underlying values for Surprise: 0.087g peak ground acceleration, 0.198g at short period, 0.076g at 1 second. Within Arizona alone, Surprise ranks 38 of 57 cities by seismic hazard - the 34th percentile in-state. Surprise has a population of about 167,564.

Bracing and bolting: the actual cost

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 Arizona 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 Arizona.

Insuring against this, not just retrofitting

A Surprise 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 Surprise's figures come from

Surprise's Category B 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 B does and doesn't tell you about Surprise.