The Sinkhole have always existed, this fundamental premise in order not to feed the concern of a phenomenon which leaves a lot to discuss after the tragedy of Tampa, when an unfortunate man, in February, was swallowed up in a hole in his sleep. The Sinkhole may be the effect of karst phenomena, and therefore natural, with collapse of the roof of the structure, but also artificial and therefore induced by a possibly incorrect exploitation of seabed soil by man.
When we speak of dolines, we are in the presence of natural phenomena of erosion of the limestone or carbonate source, however, considerable variation caused by either the water table, depth, infiltration or percolation of water which reacts with the carbonate rock.
There are many sinkholes caused by karst. Not only those of the Friuli Venezia Giulia region, known for karst phenomena driven, but also in Puglia on the board and are found striking examples of major visual impact, such as the valley of Altamura. Sinkholes can also be found in the case of basins, catchments without emissaries. In this case, when you are in the presence of the formation of a lake, surely a sinkhole and then we will find ourselves in the presence of karst phenomena driven.
Sinkholes are very dangerous and are generated by a potential right of land use by humans. The danger factor is the fact that the collapse of the roof of the structure, soil, takes place without notice and therefore represent a phenomenon very insidious and sometimes even deadly, as happened in Tampa, in February.
The formation of these pits can be generated from an erroneous assessment of the geotechnical subsoil that is loaded with the superstructures but also by the development of erosion resulting from the mutation of the movement of groundwater and in the case of the urban fabric can also be induced by man for the modification of underground and hydraulic diagrams even in the case of underground water leakage.
As anticipated failure is sudden and without warning, and for this very insidious. Obviously we can not exclude also the inability of man to predict such failures in the construction of structures and thus a lack of responsibility. Sometimes it may be generated due to subsidence of very deep rock formation completely unpredictable.