Why do sinkholes form in cities?

This particular example opened up in Guatemala City in May 2010 REUTERS/Casa Presidencial/Handout. The UK seems to be ... What causes them? Sinkholes mainly occur in what is known as 'karst terrain'; areas of land where soluble bedrock (such as limestone or gypsum) can be dissolved by water. read more

Since it would cost hundreds of millions or even billions in some cases to repair and/or replace much of that infrastructure, most cities take a "wait until it fails" attitude concerning many parts of that infrastructure. In the case of sinkholes, most of the time a water or sewage pipe beneath the street has been leaking for some time. read more

Most of the sinkholes we are seeing at the moment are at least indirectly created by human activity. They're occuring just to the sides of human constructions where rain water has been concentrated on a particular patch of ground in the form of run-off from roofs and tarmac. read more

A sinkhole, also known as a cenote, sink, sink-hole, swallet, swallow hole, or doline, is a depression or hole in the ground caused by some form of collapse of the surface layer. Most are caused by karst processes—for example, the chemical dissolution of carbonate rocks or suffosion processes. Sinkholes vary in size from 1 to 600 m both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may form gradually or suddenly, and are found worldwide. read more