Surface Collapse

(Cover-collapse Sinkhole)

Sandy soils fall into cracks caused by the slow deterioration of the limestone rocks.

Collapse Step 1

A column of sandy soils fills the empty space.

Collapse Step 2

As rock deterioration and sand migration continues, a noticeable depression forms on the surface.

Collapse Step 3

Downward erosion forms a surface depression (sinkhole) from 1 inch to several feet in depth.

Collapse Step 4

SINKHOLES

What are these underground cavities that can open without warning? Civil Engineering Associate Professor Manoj Chopra explains the mechanisms behind this natural phenomenon.

The most damage from sinkholes tends to occur in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee and Pennsylvania. Below- surface conditions make sinkholes possible for 35 to 40 percent of the United States.

Click to Learn More about Surface Depressions

Warning Signs!

Cracks in walls and foundations, doors and windows not closing properly, depressions in surrounding soil, accumulating water and creaking noises can all signal that something is happening below the surface.

Surface Depression

(Cover-subsidence Sinkhole)

Soils fall (spalling) into a cavity in the
splintering limestone substrate.

Depression Step 1

As spalling continues, the bonded clay soils form a structural arch.

Depression Step 2

Further downward soil migration causes the cavity to expand upward.

Depression Step 3

The roof of the cavity breaches the surface in a sudden and catastrophic manner, creating a sinkhole.

Depression Step 4

Click to Learn More about Surface Collapses

Natural and Man-made Causes

Changes to the subsurface water profile — including excessive rainfall, prolonged drought and groundwater pumping, changing water drainage patterns and heavy machinery operation — may accelerate sinkhole formation.