This is how likely you are to be sucked into a sinkhole
Why do these terrifying death spirals keep appearing?
Another day, another sinkhole.
As if Southern Rail needed any more excuses for their appalling services to be disrupted, a small sinkhole was discovered under the tracks at Forest Hill, close to the site of a larger one which affected services last month.
It's not the first this year in the UK: the image above shows a sinkhole taking out one unlucky car in Charlton in May, while there have been more reported across the country over the past couple of years.
And, of course, two days ago, there was this terrifying, swirling, watery monster that appeared in Australia:
Should we be worried? Are these crazy things that we used to see happening elsewhere in the world going to be happening more frequently over here? Will we be sucked out of our beds in the dead of night and swallowed up into a giant sinkhole of doom?
This is what you need to know.
What are they exactly?
Sinkholes are a natural phenomenon, which occur when acidic water dissolves a soluble bedrock, such as limestone, with a hole gradually getting larger. Eventually, as loose rock falls down into the hole, the top surface layer cannot be supported, and it collapses, exposing the sinkhole that had been there underneath all along.
So what causes the collapse? Well, perversely, it can happen after periods of heavy rain or flooding - dissolving that final piece of rock in a straw-that-breaks-the-camel's-back scenario - or it can happen where there is a sudden drainage of groundwater, as the water itself can sometimes help support what is on top of it.
They can also happen artificially, when man-made structures, such as abandoned mines, or sewers, collapse.
So what's the situation in the UK?
We tend to be fairly lucky with sinkholes in the UK; they appear to happen most frequently - and most spectacularly - in places such as China, Mexico, Florida and the Murge area in Southern Italy. Sinkholes that happen in the UK - such as the one above, which occurred in Neath, North Wales in January - are rarely more than a few dozen feet deep.
In terms of location, the South East is most vulnerable to the phenomenon, due to its chalky geology. The Isle of Wight and Yorkshire is also susceptible, but nowhere is completely safe.
So break it to me - am I going to be swallowed by a sinkhole any time soon?
Probably not, no.
It's true that more sinkholes are appearing around the UK - in early 2014, there was a five-fold increase in them, due to a very rainy winter (one near High Wycombe, which swallowed a car, can be seen above) - and with the onset of global warming, occurrences of flash flooding and heavy rain are only likely to increase.
However, you're almost certainly not going to die - despite around 32,000 sinkholes existing in the UK, no one has yet died from one. Yet.
Let's look at some other massive sinkholes though, shall we?
Yes, let's.
(Above: Guilin, Guangxi Province, China, 2012)
Probably shouldn't have parked there
Florence, Italy, 2015.
This road's a bit bumpy...
Lanzhou city, Gansu province, China, 2015.
This is crazy
Chicago, USA, 2013.
The world's deepest sinkhole
Xiaozhai Tiankeng, also known as the Heavenly Pit, located in Fengjie County of Chongqing Municipality.
Incredibly quick thinking from this Chinese traffic officer
Hangzhou city, Zhejiang province, China, 2016.
