Parts of the chalk cliffs behind Brighton Marina collapsed after the stormy night.
Around seven tons of the cliff face suddenly slid away close to the ASDA store, blocking the undercliff walk.
Ambulance and fire crews were called to the scene by staff at the store, who heard the sound of falling chalk and earth.
At first it was feared the huge landslip may have buried a walker, cyclist or jogger out on the popular sea walk.
But there was no-one underneath the 100 ft cliffs at the time.
A spokesman for Brighton Marina said::"It has blocked the underclif walk and the service road at the back of Satarboard Court at the Marina. About six or seven tons of the cliff face has fallen.
"Police, fire and ambulance services were called in case there was someone underneath at the time, but no-one was walking there at the time."
Meanwhile, a huge section of the cliffwalk disappeared into a cavern after its chalk bed collapsed after weeks of torrentail rain.
A 17 metre long section of the under cliff walk, which runs parallel to the main A259 along the seafront between Ovingdean and Brighton Marina at Roedean Bastion collapsed into a four metre hole last night.
The pathway is made up of concrete slabs laid onto a chalk bed on the cliffside and is a popular route with cyclists and walkers heading into Brighton.
Richard Pearce, a seafront officer for Brighton and Hove Council, said: "It's now closed and will take a substantial amount of rebuilding."
He added: "It's not the first time it's happened. If we have a big freeze with the amount of water in the cliffs we could have a major fall."
A spokesman for Brighton and Hove Council says the collapse was caused by a breach in the sea wall which exposed the chalk below, eroding the concrete platform.
The council plans to fill the 200 cubic metre hole with concrete by Christmas depending on the weather.
He added: "This has happened three or four times. We're advising people to stay away from it - particularly when weather is bad. They should not try to cross the gap."
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