A huge Moreton Bay fig tree at the University of Western Australia, which dates back to the Great Depression, has partially collapsed, leaving bystanders awestruck.

No one is believed to have been injured when the tree cleaved in two about 5:00pm on Monday, an incident which was captured on mobile phone footage by engineering student Tim Stanley.

In the footage, a woman who was walking towards the tree at the time is seen to turn around when someone calls out "look out".

Mr Stanley, who was visiting the university with his father and grandparents, said the sight and sound was "truly astounding".

"It took no more than 2 or 3 minutes from when we heard an explosive crack from it to this happening … we were just stunned," Mr Stanley wrote on social media.

The 86-year-old Moreton Bay fig tree split in two and collapsed in front of astonished onlookers. ( Instagram: @tims_s﻿ )

"No more than a minute before the failure, we were talking about the weight the main branches support and what an amazing thing it is.

"The sounds it was making were incredible and the total failure of the entire limb left everyone watching truly gobsmacked."

He said the noise of the tree cracking was "explosively loud" and people had come running from all directions when the branches fell.

"Before we realised what it was, my dad joked that someone's chemistry experiment had gone wrong, but then we realised it was the tree," he told the ABC.

"There was a lady walking nearby and my nanna yelled at her to get out of the way, but she had headphones on so she couldn't hear.

"She was pretty shook up as you can imagine. She said she was going to buy a Lotto ticket."

A 'massive explosion' and smell of sap

Tim's father, who was also walking towards the tree at the time, posted that the tree's collapse was "spectacular and sad".

"We heard a massive explosion a few minutes earlier whilst walking past the tree and didn't associate it with the tree," he posted on YouTube.

"Then it started cracking and I yelled for Tim to start videoing and it just collapsed before us.

"Truly a case of being in the right place at the right time. It was spectacular and sad all at once. The smell of the sap and broken tree was also something else."

The fig tree is a popular backdrop for wedding photos. ( ABC News: Julian Robbins )

The iconic tree, which stands in front of the Arts building and alongside the university's central path, is a popular backdrop for wedding photos.

According to the university's 100 Treasures book, the "magnificent" tree was planted 86 years ago.

"The story has it that in 1932 garden labourer George Munns dug a big hole, threw in a dead cow and planted the tree; an original blood-and-bone story," the book says.

'Like watching a distressing death'

A university spokesman said arborists were currently assessing the tree and the area around it had been cordoned off.

He said it appeared about a quarter of the tree had collapsed and the university's preference would be to save the tree if it could be made safe.

"It's certainly an iconic part of the university," he said.

Arborists are assessing the damage to the tree. ( ABC News: Julian Robbins )

Several people took to social media to express their sadness about the tree.

Alexis Lateef said it was "like watching a distressing death".

"I have known this tree since being a young 17-year-old Arts undergraduate in 2005," she posted.

"I used to call it 'the tree of wisdom'. It always made me draw a breath.

"You cannot imagine how devastated I feel right now."

Lorin Hall posted that she often held market stalls under the tree at local design market Upmarket, which is held at the university every three months.

"I look at it often and wonder about what it has seen in its life. I am so sad and really hope that they can save it," she wrote.