Chelsea, AL: what USGS's seismic model says

Under the seismic model IBC and ASCE 7 use for new construction, Chelsea is 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. Nationally, Chelsea ranks above 75% of the 4,875 cities in this dataset for seismic hazard - the 75th percentile.

How Chelsea compares

USGS's underlying values for Chelsea: 0.165g peak ground acceleration, 0.282g at short period, 0.096g at 1 second. Within Alabama alone, Chelsea ranks 28 of 107 cities by seismic hazard - the 75th percentile in-state. Chelsea has a population of about 17,293.

What a retrofit costs in Chelsea

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 Alabama 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 Alabama.

What this means for insurance

A Chelsea 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 Chelsea's figures come from

Chelsea's Category C 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 C does and doesn't tell you about Chelsea.