Sinkholes- Unexpected Surprises

1. Sinkholes The Unexpected Surprises

2. People need to be cautious because anything built by man can be destroyed by Mother Nature. Russel Honore

3. What is a sinkhole? The term is used for any opening in the ground, that occurs due to the erosion. They can be either caused by human activity or naturally. There are two types of sinkholes: • Dissolution • Cover- subsidence – developing over the long time • Cover-collapse – developing suddenly by collapse (Source: http://water.usgs.gov, http://greentumble.com)

4. Formation of sinkholes Sinkholes form in areas where easily water soluble rocks lie under the terrain, usually in Karst topography. Examples of such rocks are carbonate,limestone, gypsum, dolomite or rocks with high proportion of salts. It is simple. Water, rainwater or/and groundwater, slowly dissolve certain parts of such formations and carve cavities into them. Over the time the process continues and eventually a sinkhole is born, when the groundcover above such a cavity collapses because of gravity.

5. Formation of sinkholesDissolution Type • Occurs when the rock formation is not covered by the protective layer of soil and water can easily reach it with every rainfall and gradually erode the terrain. • Over the time a depression forms on the surface that eventually grows into a hole. • Sometimes these sinkholes hold water and create wetlands or lakes.

6. Formation of sinkholesCover-Subsidence Type As the name suggests, these sinkholes occur slowly due to the gradual subsidence of the terrain. • Sandy, permeable soils covering the soluble rock formation is the best environment for this type of sinkholes. • Begins from the surface.

7. Formation of sinkholesCover-Collapse Type • Fast occurrence, usually triggered by heavy rainfall. • Dangerous, unexpected. • Happens due to the erosion and cavity formation in the underground. • Sudden collapse of the layer of soil, because of gravity.

8. Human causes of sinkholes • Mining activity & creation of storage ponds • Leaky sewage systems • Groundwater extraction • Construction projects • Irrigation => changes in the balance of water and soil

9. Warning signs • Check the local topography with the local authorities, if possible. • Check the historical accounts before buying a property. • Beware of warning signs, such as cracks in walls, sudden problems with closing doors or windows, slumping trees or standing water in areas, where it was dry in previous years. • Look for changes in plant growth or terrain deformities. • Worsened water quality.

10. How to fix a sinkhole Good news. In some cases the progress of a sinkhole development can be mitigated, when detected on time. However, usually it requires professionals to do the job. Large sinkholes can be filled with boulders, smaller rocks and on gravel to provide extra support for the soil on top of such a cavity. Smaller sinkholes can be simply fixed by porous concrete and sand. Just remember, it is better to have professionals to check the size of a potential sinkhole and to determine the best method to deal with it.

11. Used sources • http://water.usgs.gov/edu/sinkholes.html • http://greentumble.com/what-causes-sinkholes/ • http://greentumble.com/how-to-fix-a-sinkhole/ • http://www.conserve-energy-future.com/causes-effects-and-types-of-sinkholes.php • http://www.sinkhole.org/CommonSigns.php