Sinkhole Risk in Miami: What the State Geology Data Show

Every Miami point checked against the Florida Geological Survey sinkhole favorability map falls in the class the survey labels least favorable to sinkhole formation (FGS favorability model, downtown Miami point; FGS class table).

The Florida Geological Survey built that statewide map with a Weights of Evidence model, trained on field work in which teams investigated over 3,600 points of interest and mapped 654 sinkholes; the result sorts Florida into four classes from least favorable to most favorable (FGS, favorability of sinkhole formation). On the Miami readings, the model returns value 1; the FGS class table labels values 1 through 7 least favorable, 8 through 10 favorable, 11 and 12 more favorable and 13 and 14 most favorable.

Each Miami reading is a separate query to the same FGS model (Coconut Grove point; Little Havana point; northwest Miami point). Four points do not map every Miami lot, but none of them came back in the favorable, more favorable or most favorable classes that the FGS table assigns to higher values (FGS class table).

The Florida Geological Survey subsidence incident database holds 4 reports for Miami-Dade County, which the database codes as Dade, and none of the four is marked as a verified sinkhole (FGS subsidence incident reports, Dade count; Dade records).

In the Miami-Dade records, the Verified Sinkhole field reads N for two reports and U for the other two; the FGS layer defines those codes as No and Unknown (FGS Dade records; FGS layer definition). Recorded widths in the Miami-Dade entries are 10.0 feet or less, and one entry lists a depth of 20.0 feet for a hole 0.9 by 0.6 feet across.

Those counts carry a caution the state attaches itself: the database may include some true sinkholes, but most incidents in it have not been field-checked and their cause is not verified, and no law ever required that sinkholes or sinkhole insurance claims be logged in it (FDEP, Subsidence Incident Reports). The counts as the database returns them are 4 for Miami-Dade and 618 for Hillsborough County (FGS; FGS, Hillsborough; Pasco; Broward; statewide).

Miami, like the rest of Florida, can see three kinds of sinkholes, solution, cover-subsidence and cover-collapse, according to the Florida Department of Environmental Protection (FDEP, Sinkhole FAQ).

For Miami readers sorting out the terms, solution sinkholes usually occur where there is little or no sediment over the limestone; cover-subsidence sinkholes develop under a thick blanket of permeable sediment that slowly ravels down into voids, leaving a gentle circular dip in the ground; cover-collapse sinkholes happen when the material bridging a void gives way all at once (FDEP). FDEP adds that after a sudden collapse the initial hole may keep growing for minutes to hours to days depending on its size, while a cover-subsidence dip forms over longer periods, sometimes as long as years.

The state will not call any place risk free, Miami included. The FDEP FAQ answers the question of a safe area with "Technically, no," because carbonate rock lies under the entire state and sinkholes could theoretically form anywhere, while adding that there are definite regions where sinkhole risk is considerably higher (FDEP). FDEP describes karst as terrain produced by the dissolution of limestone or dolomite, the two most common carbonate rocks in Florida (FDEP, Sinkholes).

A sunken spot in a Miami yard or street is often not a sinkhole at all, because broken pipes, septic tanks, loose fill and buried debris can mimic one (FDEP, Sinkholes).

For a Miami owner, the FDEP checklist of look-alikes starts with damaged sewer lines and storm drains and failed septic tanks, then fill dirt that was never compacted properly after digging, and finally rotting logs, trash or other material buried on the lot (FDEP).

For a Miami owner checking a sunken spot, FDEP also lists subsurface expansive clay or organic layers that compress as water is removed as a cause that can mimic sinkhole activity, and FDEP says many such spots are never confirmed by a licensed geologist or engineer, which leaves the cause unknown and the event filed as a subsidence incident (FDEP).

For a Miami street or sidewalk problem that poses no immediate danger, Miami-Dade 311 takes reports of neighborhood problems online, through the 311 Direct app or by phone, for both Miami-Dade County and City of Miami services (Miami-Dade 311). FDEP's first instruction, ahead of everything else on its sinkhole page, is to call local law enforcement whenever someone could get hurt (FDEP).

A Miami policy must cover a catastrophic ground cover collapse, while wider sinkhole loss coverage costs extra, under Florida Statute 627.706 (Florida Statutes, section 627.706).

For a Miami claim to qualify, the statute sets four tests that must all be met: the ground gives way abruptly, the resulting hollow can be seen with the naked eye, the insured building and its foundation suffer structural damage, and a government agency with that power condemns the building and orders it vacated (Florida Statutes). The statute requires all four.

Before selling the optional sinkhole loss coverage on a Miami home, an insurer can insist on inspecting the property, and the statute lets a home policy set the sinkhole deductible at 1, 2, 5 or 10 percent of dwelling coverage, each with a matching premium discount (Florida Statutes). The FDEP FAQ notes that Florida law requires insurers to provide catastrophic ground collapse coverage, and it points Miami policyholders with claim questions to the consumer services division of the state's Department of Financial Services (FDEP; FDEP).

Florida has no public sinkhole inspector, so a Miami owner phones the Florida Geological Survey helpline, 850-245-2118, for guidance and, for an assessment, contacts a certified home inspector or foundation specialist (FDEP, Sinkhole FAQ; FDEP).

For a Miami homeowner, the state FAQ is blunt: no Florida agency is charged with inspecting sinkholes, and the FGS does not have enough staff to visit each new one, though it asks people to file a subsidence incident report so the case enters its database (FDEP). The Sinkhole Helpline exists to clarify the FAQ, answer other sinkhole questions and give verbal guidance on a sinkhole situation (FDEP).

The Florida Geological Survey publishes Leaflet 20, A Homeowner's Guide to Sinkholes in Florida, and a Map Direct viewer for its subsidence incident data (FDEP; FDEP, Subsidence Incident Reports). The FDEP subsidence page was last modified January 22, 2026. Last verified: October 18, 2026, by querying the FGS favorability model at four Miami points and the FGS subsidence database by county, and re-reading the FDEP sinkhole pages and Florida Statute 627.706.