Samantha Murphy: Grim warning issued as volunteer search continues trends now

Good Samaritans wanting to join the search for missing mother-of-three Samantha Murphy have been warned to take care due to treacherous terrain.

Volunteers have taken it upon themselves to coordinate searches in the Woowookarung Regional Park, northwest of Melbourne, since the official search for Ms Murphy was scaled back on Saturday.

The 51-year-old hasn't been seen since the morning of February 4, when she vanished while going for a run through the state forest.

Ballarat Mayor Des Hudson said while it was encouraging to see that locals were keen to help with the search, there were many risks in the rugged bushland.

'It's important they heed advice posted on the Buninyong Police Station front door which identifies areas of interest to search and strategies to keep safe,' he told Sky News.

'The last thing we want and emergency services need is to direct resources to someone who has been lost.'

Volunteers have been urged to search in pairs and ensure they have adequate food and water with them.

Organisers have also been writing down the names and numbers of those helping with the search.

Locals had earlier raised concerns of mineshafts around the state forest that aren't easily spotted. 

'Ballarat is a town that was built on gold, lots of gold mines are out there - and people have to be mindful of that when they are searching,' Mayor Hudson added. 

There were 28 people helping with the search on Sunday, according to a Facebook group set up to assist in Ms Murphy's disappearance, which has now been shut down.

The warnings come after professional tracker Jake Cassar told Daily Mail Australia that Ms Murphy could survive in the bush for weeks provided she has access to water.  

'She could absolutely be alive if she found her way to water,' he said.

'You can go about three days without water and about a month without food, but people have survived for months in the past.'