Hayle cliff fall 'could happen again' experts warn
Experts believe there could be further cliff falls at the site of a massive collapse in Cornwall.
Thousands of tonnes of rock fell into the sea at North Cliffs near Hayle two weeks ago - just days after part of the coastal footpath was diverted.
The collapse was recorded by geologist Richard Hocking - a soils and materials engineer for Cornwall Council.
More cracks have appeared along the cliff top, prompting fears of another collapse.
Experts say a further 10 to 15m (33-49ft) of the cliff is at risk, but there is no way of knowing exactly when it could happen.
The council said a large crack in the cliff path was first reported to Devon and Cornwall Police and the Maritime and Coastguard Agency by a jogger on 19 September.
Following an inspection and assessment by Mr Hocking and a National Trust countryside officer, the decision was made to divert the path inland away from the crack.
The countryside officer contacted Mr Hocking on 22 September to say the situation had worsened and large tension cracks were opening up.
The next day, following reports from the public of rocks falling from the cliff, Mr Hocking returned again to assess the situation and watched as an estimated 200,000 tonnes of rock collapsed.
"I've been a geologist for 28 years and that was certainly the most exciting thing I've ever seen," he told BBC News.
"I just happened to have my camera with me and thought I'd give it a go.
"I've never used it on video mode before, but I set it going and managed to capture the massive failure."
The collapse of the cliff is thought to have been caused by a deep-seated inclined fault plane on which the rock mass slid.
"These failures are not uncommon along this section of coast, although this is one of the most dramatic ones in recent years and was probably caused through weathering and fluctuating groundwater pressures," Mr Hocking said.
Mr Hocking put the video on YouTube - hoping to attract comments from other geologists - but it has since been viewed more than 750,000 times and copied and shown around the world.
"It's the highlight of my career," the geologist added.