Ripon sinkhole: Here's what we know so far
Emergency services said a sinkhole has opened up in Ripon North Yorkshire.Here's what we know so far:
What exactly has happened?
A hole appeared in the gardens of Magdalen's Road, in Ripon, North Yorkshire on Tuesday night. North Yorkshire Fire and Rescue said there was no injuries but seven properties have been evacuated.
How deep is it?
Firefighters say the sinkhole is 66ft (20m) wide by 33ft (10m) with an 'unknown depth.'
Hasn't this happened before in Ripon?
The Ripon area is prone to sinkhole activity and this incident is close towhere another opened up beneath a 100-year-old building in Magdalen's Close in 2014, leaving it in a precarious state.
So are they common in Ripon?
They are relatively common in Ripon and are usually caused by thedissolution of thick gypsum deposits beneath the area.
After the 2014 partial house collapse, the British Geological Survey (BGS) said gypsum under the town had dissolved to form a maze-like cave system.
It said in a report that sinkholes appeared in Ripon every two or three yearsin the 1980s and 1990s but there had not been any reported in the seven years before the 2014 event.
The BGS said there were a number of possible triggering mechanisms, relating to action of water underground.