Bournemouth seafront landslide caused by rainfall
Teams are working to clear a "significant" landslide that blocked the promenade between Bournemouth and Boscombe's piers.
The 20-metre wide (65ft) strip of cliff face fell onto the promenade and beach access road at around midnight.
Portland coastguard watch commander Malcolm Wright said: "Because of the rainfall that we've had, the ground near cliff tops will be saturated.
"With the extra weight of water landslides are inevitable."
A cordon was been placed around the area at the top and bottom of the cliff and tractors worked to move the sand and debris on to the beach.
Police and fire crews used heat-seeking equipment to ensure there was no-one underneath the pile of sand and vegetation.
No injuries were reported but the coastguard urged people to stay away.
Bournemouth seafront manager Chris Saunders is already overseeing the clear-up of 387 beach huts on the borough's coastline, which were damaged or destroyed either by landslips and storms.
He said: "It's not an uncommon occurrence. It's not a huge slip - we've had worse over the years.
"We had a cliff slip down at Gordon's Corner, at Southbourne, just before Christmas that wasn't quite as big as this but did more damage because it was where some beach huts were.
"About three or four years ago just the other side of the East Cliff lift we had a substantial cliff slip that went through the back of a building.
"Knowing we've had the heavy rains, we commissioned a geotechnical expert to come and check the cliffs through but this has slightly beaten us to it."
A second rock fall has taken place at about midday at Monmouth Beach, Lyme Regis.
The area has been cordoned off, with no injuries reported.