Lifeguard Ben Quigley said in an Instagram video that it was lucky it was a rainy day and no one else was around. A beachgoer in the video described it as “the loudest crack of his life”.
Another witness of the cliff collapse, who asked not to be identified, said he felt the ground shake and heard a loud crash, which he thought was from a nearby construction site.
The council is investigating whether heavy rainfall contributed to the collapse.
“Assessments are ongoing, but it appears sustained heavy rainfall may have contributed to the section of the cliff slipping, beneath which a stormwater drain – or culvert – ran,” the council said in a statement.
“The culvert and a safety rail were badly damaged during the slip. A geotechnical assessment will be conducted to ensure the stability of the cliff area and to determine whether the exclusion zone needs to be extended.”
Professor of Coastal Geomorphology Ana Vila Concejo, from the University of Sydney, said rockfalls are natural on sandstone cliffs fractured over time by strong waves.
“Once in a while, under the right circumstances, the wave power is strong enough to facilitate this rockfall,” she said.
“It is something that happens often … If you walk from Maroubra to Malabar, there is a spectacular fall of rocks there that happened in the last few years, but because it didn’t fall on any infrastructure, it didn’t receive any attention.”
Another local, Ben Robinson, said he had recently walked over the stormwater pipe.
“Two days ago, I was walking down the stairs that are now smashed. It’s crazy,” he said.
The beach is closed due to dangerous surf conditions.
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