Sunshine Coast Council is urging people to stay away from the Moffat Beach Seawall due to the risk of falling rocks and injury.
It comes as the seawall was damaged during February's severe weather event.
Cracks have appeared at the top of the wall and some sections are beginning to subside.
Sunshine Coast Division 2 Councillor Terry Landsberg said council had acted quickly to fence off the area and urged people to follow signage for their own safety.
"Beach accesses, picnic tables, seating and the boat ramp have been closed and we ask people to not walk along the beach, near the wall," Cr Landsberg said.
"There is a significant risk of the wall deteriorating further and if that occurs, rocks falls are highly likely.
"The rocks can fall onto the beach at any time, and if it does, it will happen fairly quickly – within about 10-20 seconds – which means that anyone standing at the base of the rock wall will be injured.
"Independent geotechnical and coastal engineers are being engaged to assess the damage and provide recommended solutions – however it could take up to six months for the repairs to be finished.
"The safety signage and fencing will remain in place for the duration and the beach to the north of the seawall can still be accessed via Eleanor Shipley Park.
"The health of the trees along the foreshore will be regularly monitored by an arborist.
"Our community's safety remains council's top priority throughout the project."
The cost to repair the seawall is unknown at this stage.
Council has set up a webpage to keep the community informed as the investigation continues at www.sunshinecoast.qld.gov.au/mbseawall
