Philadelphia, PA: what USGS's seismic model says

Under the seismic model IBC and ASCE 7 use for new construction, Philadelphia is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Philadelphia in the 57th percentile nationally for seismic hazard - higher than 57% of the 4,875 US cities USGS was checked against here.

Where Philadelphia sits in Pennsylvania

USGS's underlying values for Philadelphia: 0.102g peak ground acceleration, 0.182g at short period, 0.048g at 1 second. Within Pennsylvania alone, Philadelphia ranks 20 of 193 cities by seismic hazard - the 90th percentile in-state. Philadelphia has a population of about 1,573,916.

Retrofit economics for Philadelphia

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 Pennsylvania 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 Pennsylvania.

Earthquake insurance for a Philadelphia home

A Philadelphia 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 Philadelphia's figures come from

Philadelphia'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 Philadelphia.