Question: hello scientists, Venice is slowly sinking. Is there an explanation why? maybe when im older then venice will not exist? thanks

Ceri-Wyn Thomas answered on 24 Jun 2010:

Hello Embry! Venice is built on sediments from the Po River in Northern Italy. These sediments
have only been deposited recently (in geologic time) so have not yet turned into proper rocks. There is still lots of space between all the sand and mud grains that is filled with water (like a sponge). As more
layers, and buildings, are put on top, the water is squeezed out of the spaces and the sediments are compacted (like a sponge when it’s squeezed). This has been happening gradually at Venice for many centuries, and it is the compression of the underlying rocks that causes the subsidence. However, the subsidence was made worse in the last 100 years when people on the Italian mainland began extracting the waters from the rock to use for drinking and washing etc. They didn’t realise at the time, but removing all this water allowed the sediments to compact even more, causing further subsidence. This has now been realised, and efforts are being made to reinject water into the compacted layers to prop them up again, and they may build a wall or ‘dyke’ to keep the sea out, like Holland has done. But it is not clear that this will work, so it’s clear that Venice has some serious problems. As the bible story says, try not to built your house on foundations of sand. I hope you get to go there someday! 😉