Lisbon, Portugal, Sinkhole

A parked bus was the unfortunate “meal” of a sinkhole that opened up in the streets of Lisbon, Portugal, in 2003.

Anything that increases the flow of water into subsurface soil can speed up the formation of sinkholes. In many cities, utility infrastructure such as sewer lines and fiber optic cables are buried in troughs filled with loose material, which can wash away over time. In some cases, a stretch of road can essentially become a concrete bridge over mostly empty space.


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