Portland, TN: what USGS's seismic model says

Under the seismic model IBC and ASCE 7 use for new construction, Portland is Category D. 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, Portland ranks above 79% of the 4,875 cities in this dataset for seismic hazard - the 79th percentile.

How Portland compares

USGS's underlying values for Portland: 0.124g peak ground acceleration, 0.255g at short period, 0.132g at 1 second. Within Tennessee alone, Portland ranks 60 of 104 cities by seismic hazard - the 43th percentile in-state. Portland has a population of about 13,651.

What a retrofit costs in Portland

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 Tennessee 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 Tennessee.

Insuring against this, not just retrofitting

A Portland 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 Portland's figures come from

Portland's Category D 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 D does and doesn't tell you about Portland.