Date:20 June 2013
Many parts of the world – Gauteng´s West Rand, for instance – sit on land where subsurface rock, such as limestone, can be dissolved by groundwater and is particularly susceptible to sinkholes, caves and fissures – what geologists call karst terrain. A sinkhole begins forming when rainwater seeps into the karst bedrock. Once there, the water, made acidic by absorbing carbon dioxide, dissolves the rock along cracks. As the cracks become bigger, soil falls into them and the ground starts sinking. The problem compounds itself until the land completely gives out, sometimes with tragic consequences: in February, a man died after he and his house suddenly dropped into an abyss in Florida, one of the US state’s 15 000 verified sinkholes.
In this video, you’ll see a giant sinkhole swallow two buildings in Guangzhou in China. Thankfully, no one was hurt in the collapse, as the people who lived in the buildings had moved out…
(Image credit: Getty Images)