The dramatic moment tonnes of cliff collapsed at Whipsiderry was captured on video.
Around five metres of cliff top fell onto the beach along with fencing around the construction site on Wednesday at 1pm.
No one was injured during the incident but fears have been raised more cliff could come away at any moment.
A person walking their dog was picked up by Newquay's D-class lifeboat and several surfers had to paddle around to Porth Beach as it was too dangerous for them to walk back up the steps by the cliff.
Police have cordoned off the steps leading down to the beach and the surrounding footpath for safety reasons.
Specialist engineers from Cormac have carried out investigations into why the cliff collapsed.
People are being warned to stay away from Whipsiderry Beach following a massive cliff collapse.
A spokesperson for Cornwall Fire and Rescue Service said: “We want to advise everyone to stay away from the cliffs in and around Whipsiderry Beach following the big cliff fall.
“Please stay away from the top area and at least an equal distance of the height of the cliff back from the base.
“This is a very dangerous area and further falls are expected.
“Stay safe everyone.”