Sink holes are slowly becoming a common feature

We keep reading news about sink holes that swallow buses, human beings and other objects that get trapped where sink holes appear. 

Sink holes can happen anywhere without notice.They mostly form in areas what is called ‘karst’ terrains.   Reports have it they happen when rocks under the surface of the earth melt due to ground  water dissolving them over a period of time lasting for several years.  The rocks that succumb are mostly   limestone, gypsum or carbonate rocks.

This could also be man made as it happened recently in China. The construction work that is carried on  rewlentlessly resulting in  bursting   of storm water drains and other water bodies. 

Flordia is yet another place this is reported frequently. 

Source:https://in.news.yahoo.com/explained-sinkhole-swallowed-bus-pedestrians-133936520.html