Sinkhole Risk (v1)
Version 1.0.0 · Published 2026-06-19
What this is
Florida's "Sinkhole Alley" (Pasco, Hernando, Hillsborough, Pinellas and the wider west-central karst belt) is a real, state-specific hazard that national property tools miss. It matters for both safety and insurability: sinkhole damage is excluded from standard Florida homeowner policies and needs separate catastrophic-ground-cover coverage. This category reports how many subsidence incidents have been reported near the property.
Data source, and an honesty note
We query the Florida Geological Survey (FGS) Subsidence Incident Reports, the state's database of reported ground subsidence, live for incidents within one mile of the address. Critically, the FGS states that most of these incidents have not been field-verified by a geologist, and the cause is often unknown, so a nearby report is a "look into this" signal, not a confirmed sinkhole. We treat it accordingly: gently, and never as proof of a sinkhole.
Tier-firing rules
| Tier | Trigger (reports within 1 mile) |
|---|---|
| MODERATE | A reported incident within ~0.25 mile, or 10+ reported incidents within 1 mile (an active subsidence area). |
| MINOR | 1 to 9 reported incidents within 1 mile. |
| none | No reported incidents within 1 mile. |
How it affects the grade
Because the underlying reports are mostly unverified, sinkhole is deliberately excluded from the "dominant feature on the parcel" rule that can cap a grade at D, a single nearby report must never single-handedly force a failing grade. A moderate sinkhole signal contributes like any other moderate hazard through worst-feature-wins and the count modifier, and the report tells you to get a professional geological inspection and to confirm sinkhole/catastrophic-ground-cover coverage before you buy.
What v1 does not yet include
- The FGS karst-favorability geology band (a slower-moving susceptibility layer) as a second signal.
- Florida OIR county-level sinkhole-claim rates.
Source: Florida Department of Environmental Protection / Florida Geological Survey, Subsidence Incident Reports. Reported incidents are largely unverified; confirm any concern with a licensed professional geologist.