Earthquakes, tornadoes floods, hurricanes,
and landslides cost homeowners millions of dollars in damage each year; us
Floridians have always focused our attention to hurricanes, but with growing number of sinkholes being reported the focus is shifting.
Sinkholes are naturally occurring holes in
the surface of the earth. They can form gradually over time as the underground water
dissolves layers limestone bringing the soil with it or suddenly.
In addition to Florida being
made up of a young very weak, porous, Limestone that is easily weathered by the
extreme conditions endured throughout storm season. Pumping from aquifers increases the chances of formation. As well as droughts that cause low ground
water levels, that reduces the support of a cavity or the combination of low
ground water then heavy rains or floods.
Sinkholes can also be caused by growing population
and development. The changes in drainage patterns, construction, and heavy
traffic all have impacts. Building in areas like “sinkhole alley” with
limestone depth less than 200 feet are examples of the modern sinkholes that we
see on the news today.
Whether natural or man induced, there are
many types of sinkholes. The most common three are:
- · “Solution” sinkholes: when the limestone is exposed at the surface or covered by a thin layer of soil leaving the limestone subject to physical and chemical process that break downs the rock forming a cavity or void. These type develop slowly, but are continuous.
- · “Cover-subsidence” sinkholes: when the sand layer is around 50-100 feet with very little clay around it. As the limestone dissolves, sand falls in filling the void. These types are known to not get very large in diameter or depth due to the sand fill.
- · “Cover-collapse” sinkholes: when the solution cavity develops in the limestone that the overlaying cover material can no longer support the weight. Greater chance of collapse when the limestone aquifer is below level.
Certain Signs that a sinkhole is about to
open up.
-Slumping trees or fence posts
-Formation of small ponds where they had not
been before
-Wilting of small area of vegetation in
circular pattern
-cracks in building foundation
If you notice signs
-provide safety for your
family. Evacuate if necessary
-secure or move valuable
possession safely
-Notify your insurance
company
-Mark the sinkhole or
property with tape or rope to signify danger.
* You could be held liable if
someone is injured.
For those who are buying a home...
- Be sure that the house is insurable. Is sinkhole coverage included in your policy?
- Hire a home inspector that can find signs of potential activity (especially in central-western Florida)
