Sink holes happen, can be over old mines or over geological features such as under-ground caves (for example and under-ground river or lake that erodes limestone) Once the gap between the hole and the surface gets sufficiently small, or the building or infrastructure on top becomes sufficiently heavy then they cave in!
There are loads of examples on the internet, some alot bigger than that one, and if you look at the lack of foundations, and soil consistency in the images, they were kinda asking for something to go wrong.... building your house on sand and all that!
