The huge cracks run wide and deep in the crumbling cliff faces along the Great Ocean Road, threatening to send massive sheets of rock and sediment cascading onto the beaches below.
Many who live along the coast or study these fissures know that the next major collapse is coming soon.
The biggest rock falls along the Surf Coast are pushing cliff edges inland up to five metres at a time and there have been more landslides in recent days.
Debris after a landslide on the Surf Coast. Credit: Jason South
The deadly potential of these landslides was proven on New Year’s Eve when a man was killed near Bells Beach, while Demons Bluff near Anglesea has been permanently closed due to rock falls.
Heavy downpours of rain are exacerbating the unstable conditions and raising the likelihood of more falls after Victoria experienced its wettest January in just over 10 years.
The continued crumbling of cliffs has raised questions about the future of infrastructure such as walking trails and even the position of the Great Ocean Road itself.
Melbourne University coastal erosion expert David Kennedy said more falls were inevitable with cracks longer than 45 metres developing along the cliff face at Demons Bluff.
He has been monitoring the cliff face together with local “citizen scientists” and has recorded more than five falls a year since 2018.
Surf Coast geologist Kim Straub at Addiscot Beach where cliffs have been crumbling. Credit: Jason South
The biggest collapse recorded was 3000 cubic metres of rock and sediment — larger than the volume of an olympic swimming pool.
Professor Kennedy said the largest falls had forced the cliff edge back by five metres.
“They’re barely hanging on at the moment,” he said. “If we’re going to get more rain events and wet summers, we can expect to get more falls.”
But landslides were also likely at sandstone cliffs at Portsea on the Mornington Peninsula where it faced the open ocean, Professor Kennedy said.
Parks Victoria district manager Dale Antonysen said the decision to permanently close access to Demons Bluff was based on public safety risks that landslides posed on this section of coast.
“The cliffs in this area have large tension cracks in the order of 50 metres in length and two metres in depth, which indicated further collapses are inevitable – there was another large slip at Demons Bluff just at the end of January,” he said.
A large crack at Demons Bluff.
He said the most recent large landslide nearby at Jarosite Headland took place within an exclusion zone set up where the man was killed on New Year’s Eve near Bells Beach.
An area 450 metres long and 35 metres from the base of the cliffs will now remain closed until further notice.
“Nobody is allowed into this area, and we’ve updated signage to reflect that change. We’re also asking people not to stop within 35 to 50 metres of the cliff.”
Geologist Kim Straub, who lives at Bellbrae on the Surf Coast, said the cliff faces were made of soft rock vulnerable to landslides.
“On these particular faces, you’ve got fractures that run parallel to the angle of the cliff face and that’s where the slides happen,” she said.
Ms Straub said better signs were needed to warn people of the dangers.
“Over the years, I’ve seen people up against the edges of those cliff faces, and I’ve gone and warned them.”
Demons Bluff after part of the cliff collapsed. Credit: Nine
However, she said landslides were a normal part of coastal erosion. “It definitely will keep happening. That’s the way the Earth works.”
Two sections of the Surf Coast Walk have been relocated at Demons Bluff and Aireys Inlet after assessments identified safety risks.
The Great Ocean Road Coast and Parks Authority confirmed several cliff areas between Jan Juc and Point Roadknight as well as Aireys Inlet were also susceptible to instability.
Authority chief executive Jodie Sizer urged beachgoers to remain on designated tracks and not walk or sit underneath the cliffs.
“Landslips are unpredictable and the size of material that falls onto the beach can be very large, with rocks and debris a potentially fatal hazard,” she said.
A warning sign south of Bells Beach. Credit: Jason South
Tourism strategist Suzanne Cavanagh, who has had a house at Aireys Inlet for 20 years, said the Great Ocean Road’s image as a nature-based holiday destination might suffer because of the dramatic images of coastal landslides and erosion circulating on social media.
“They’re quite dramatic images,” she said. “We’ve got a potential problem.”
Coastal planning and management expert Geoff Wescott said the coast had always been eroding, but it now appeared to be accelerating.
He said wild weather might be contributing to large sheets of cliffs peeling away.
“Anglesea has had some really vicious storm cells just these last three or four months,” he said.
Dr Wescott, an honorary research fellow at Deakin and Melbourne universities, said sections of the Great Ocean Road might have to be closed one day because of instability in the cliffs.
The Great Ocean Road Credit: iStock
“I would imagine at some point it will just be untenable to keep it open completely end to end.”
Erosion has already come perilously close to the road in locations including Apollo Bay.
But Environment Minister Lily D’Ambrosio insisted there were no plans to move parts of the Great Ocean Road because of coastal erosion.
She said the government was working with other authorities to develop coastal adaptation plans identifying short and long-term options to manage the effect of storm surges, wave attacks and rising sea levels.
“Like many coastlines, the Great Ocean Road is vulnerable to erosion and the impact of climate change. This is why we have been upgrading and improving Victoria’s No.1 tourist route.”
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