What is a sinkhole?

[BetteDavis01]

Does anyone know what causes them? I keep hearing about them on the news and there seems to be a new one appearing everyday. TIA

DH suggested something to do with underground streams and rivers eroding the earth and causing some sort of collapse into underground spaces.

Or something. I wasn't really listening at the time.

They can be artificial (old mine shafts etc) or natural (underground streams, gaps between rocks). If it rains enough, the earth on top becomes too soft and just falls into the hole.

I think.

Just watched BBC news and sarahs husband is spot on. Water underground dissolves some soil/ earth types and eventually everything above it collapses.

There was an excellent programme on BBC2 about natural sinkholes just a few weeks ago. It focused on the ones in Florida as apparently that is the most active place in the world for them. It is still available on iplayer for another 12 days

It's all to do with rock types - some will dissolve over time if exposed to water. When the rock has dissolved sufficiently to not be able to support the weight of the soil above it, it will collapse in on itself, leaving a sink hole.

I read a book once where a murderer hid his bodies in a sinkhole. There's no getting them back for forensics, I remember that much.

In this area there are parts with a lot of gypsum underground.The water erodes it and makes underground cavities, eventually the weight above it becomes too great and the surface collapses and falls down into the cavity leaving a big hole.

They're quite common in Limestone areas apparently.

I'm glad you asked. I've been wondering too. These ones that swallow whole houses - where do they actually go?

I mean how far down do they go?

Scares the shit out of me. Florida is supposed to be one big sink hole. I don't think I could live anywhere if I knew it was at risk of that. Same with earthquakes.

yes gypsum or limestone, such as the karst around Trieste or in Florida, or chalk such as in the south of England. Or old mine workings.
(been reading up on sinkholes)

The Etihad stadium in Manchester was built over and around old mines. It triggered off a cluster of around 100 earthquakes back in 2002.

Makes you wonder about all this fracking malarkey.

The most recent sinkhole was from gypsum dizzolving.
A geologist on tv said that a van sized lump of gypsum in a river would disappear within 18 hours.

Dissolve?

Yes, I've wondered if fracking would increase chances of sinkholes.
I've read it increases earthquakes.

I feel so sorry for those people and their neighbours, they will never sell their homes, never get insurance.....they are stuck. :(

BBC article posted today was really interesting: www.bbc.co.uk/news/science-environment-26242258

Making of a sinkhole

I have one between two of my fields but as it's covered up by fifteen feet of soil, you wouldn't know it was there. I do, however, crap myself when I drive over it!

The structure of surface land is that it is holds together sufficient enough for me to traverse it - the ground has essentially built a bridge over the water flow. However, if the ground water swells (e.g. surpass it's river capacity, just like a river, it would 'burst its banks'. The water would be forced into the weakest spots. Ergo, the pressure of a group of houses together, the weakest spot would be the garden area.

Just like squeezing a spot - all the stuff comes out of a diddy weakpoint!

e.g. surpasses its water capacity.

Shit I need to go back to school!

Terrortree you drive over it??? Fuck that

In my tractor! But that is the sinkhole I know about. I could have 100 more that I don't know about.

Live life on the limit me!

We've just had one in town today. My initial thoughts were for the poor homes and businesses nearby. It wil bugger teir insurance

And saying that I've just had confirmation it wasn't one

Mother Nature is certainly calling the shots. You can't fight her and shouldn't mess with her.

Honeydragon Phew!