Australian scientists sounded alarm on the possibility that catastrophic tsunami waves could swamp Queensland coastlines in the event of a very powerful earthquake hitting the region.

The deluge would be likely triggered by the collapse of a one-cubic-kilometre undersea slab, which marine geologists had recently detected while conducting mapping research mission near the Great Barrier Reef.

The undersea slab is now known as Noggin Block, according to Dr Robin Beaman of the James Cook University, which he added has been recently observed "is in the very slow, early stages of starting to break away from the edge of the Great Barrier Reef."

"It's actually up on the top of the continental slope in about 350 metres of water," Dr Beaman told ABC on Friday, adding that this specific threat was spawned by an underwater landslide that occurred deep in the area.

"If it were to break away catastrophically, that is break away really quickly, what that would do is it would create a surface wave above it. It would actually cause a tsunami," the Aussie scientist warned.

He added that "it is absolutely going to collapse and when it does fall it will fall one kilometre into the adjacent basin."

These deadly waves would pack enough power to reach nearby Australian shorelines, inundating on its way coastal areas in Northern Queensland such as Mourilyan Harbour and Clump Point, Mr Beaman said.

However, for the block to slide down much deeper, the movement would need to be triggered by an epic seismic disturbance, which Mr Beaman stressed is highly unlikely anytime soon.

"We're not trying to alarm people, but we need to know it is there and what could happen when it falls," the geologist was reported by Agence France Presse (AFP) as saying.

"We should be aware that these things exist. We don't really know when such a block might collapse. All I can say is sometime it eventually will," Mr Beaman added.