Toowoomba’s Wagner brothers were defamed by a 60 Minutes report broadcast on the Australian Nine Network in May 2015 that incorrectly insinuated they were responsible for the destruction of the town and deaths of 12 people, a Brisbane supreme court jury found.

Nine and journalist Nicholas Cater were ordered to pay each of the four brothers $900,000 plus interest.

Denis, John, Neill and Joe Wagner said the report insinuated the collapse of a wall of a Lockyer Valley quarry they owned caused the “man-made catastrophe”.

The report, entitled “The Missing Hour”, described the wall of water that fatally swept through Grantham as an “inland tsunami”.

The report does not expressly blame them for the deaths but the family believes it led people to believe they caused the disaster, sought to cover it up and refused to answer to the public.

The judge was scathing of the network’s “unjustifiable” conduct, saying it was recklessly indifferent with the truth.

“The Nine Network had information that contradicted the allegations contained in the programme but did not broadcast it,” he said.

He said Cater’s conclusions were expressed as a result of extensive investigative journalism supported by eyewitnesses but he “did not contact any of the Wagners about the allegations he made about their quarry”.

The judge said Cater’s and Nine’s careless actions were exacerbated by their failure to retract or apologise once it became clear their report was flawed.

“60 Minutes and Mr Cater’s respective defamations caused substantial injury to the Wagners’ reputations for integrity … and great harm to them personally,” he said.

The judge said the accusation the Wagners failed to take steps to prevent the quarry wall collapsing, which led to the deaths and town’s destruction, was an “extraordinarily serious defamation.”

“The programme included vision of the devastation of Grantham and the trauma of flood victims, including the inconsolable grief of a mother whose infant was taken from her arms in the flood,” he said.

Outside court, Denis Wagner said the family was pleased the truth had come out.

Nine and Cater were ordered to pay each of the four brothers $600,000 and $300,00 respectively.

Nine said it would review the judgment and consider its position. Cater declined to comment.

This decision acts as a reminder to journalists who make investigative programmes to ensure that facts are portrayed in a fair and accurate way and those accused of wrongdoing are offered a right of reply.