Novarly Parcel · Philadelphia, PA
Is your Philadelphia home sinking?
Satellites have measured Philadelphia's ground to the millimetre: across 27,188 grid cells, the fastest-sinking spot moves 8.5 mm/yr. Check any Philadelphia-area address for free.
| Measured grid cells | 27,188 |
| Median ground motion | 0.7 mm/yr downward |
| Fastest-sinking cell | 8.5 mm/yr |
| Cells at notable rates (≤ −3 mm/yr) | 0.3% |
Satellite InSAR measurements on a ~100 m screening grid (negative = sinking). Sources: Ohenhen et al. InSAR VLM datasets (CC0/CC-BY); contains modified Copernicus Sentinel-1 data. Data updated 2026-07-23.
Screening only — not a structural guarantee. For any decision, consult a licensed geotechnical engineer.
Is Philadelphia sinking?
Parts of it, measurably. Across 27,188 satellite-measured grid cells in the Philadelphia metro, the median ground motion is 0.7 mm/yr downward, the fastest-sinking cell measures 8.5 mm/yr, and 0.3% of measured cells exceed the 3 mm/yr "notable" threshold. Motion varies block by block — check your specific address.
How do you measure ground motion in Philadelphia?
InSAR: radar satellites (Copernicus Sentinel-1) compare the phase of millions of radar returns across years of passes, revealing millimetre-scale vertical land motion. The data comes from peer-reviewed research (Ohenhen et al., Nature Cities 2025 and related datasets) and is screened on a ~100 m grid.
What should Philadelphia buyers and owners do with this?
Use the free screening for the measured rates around any address. An amber or red result is context for a professional conversation — share the report with a licensed geotechnical engineer or structural surveyor. A green result means no notable motion was measured nearby; it is not a guarantee.