The East Coast Low of May 25-26 1974 (known as the Sygna Storm) is regarded as the most ferocious storm to ever strike Sydney. The city was pounded by heavy rain, strong winds (up to165km/h) and record swells of nine metres along the city's coastline. the worst damage was reported on the city's beaches, which were heavily eroded. The following fortnight saw another two East Coast Lows hit the city, which only worsened erosion.
The worst hit area was at Bilgola Beach, where homes in June 1974 were threatened with collapse which was quite similar to what happened at Collaroy this year. Below are two pages of coverage from June 5 1974 edition of The Manly Daily.
An almost intact pool fell into the sea, just like at Collaroy earlier this year.
A seawall was built (presently under the dunes) to protect the homes. Fortunately they were saved as this front page clipping from The Manly Daily of June 12 1974 shows.
It is inevitable that the homes on the beachfront will be threatened again in the future as natural processes reshape the beachfront and retreat inland. There is no date for when it will happen, but luckily locals have not had to deal with the threat of losing their beachfront homes since that storm.