Does Plainfield, IN need an earthquake retrofit?

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Plainfield in Seismic Design Category C: Moderate seismic hazard. Code adds irregular-building restrictions and requires bracing of some nonstructural components (e.g. tall shelving, water heaters) in addition to structural detailing. That puts Plainfield in the 70th percentile nationally for seismic hazard - higher than 70% of the 4,875 US cities USGS was checked against here.

How Plainfield compares

The raw figures: peak ground acceleration 0.102g, short-period spectral response 0.199g, 1-second spectral response 0.089g. Among 126 Indiana cities in this dataset, Plainfield ranks 27 for seismic hazard, the 79th percentile within the state. About 37,796 people live in Plainfield, Indiana.

Retrofit economics for Plainfield

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

More on how this number was built

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