Warning: The video above contains confronting images.
WorkSafe says the owners of Whakaari White Island made a million dollars a year in profits from tours to the island but failed completely in their health and safety obligations.
In its opening statement in the trial, WorkSafe's lawyer said Whakaari Management Limited and the Buttle brothers never bothered to understand the risk - even after a similar eruption three years before the 2019 disaster that killed 22 people.
A video shown at the trial on Tuesday captures the terrifying moments when the volcano erupted and tourists and staff ran for their lives.
The way WorkSafe tells it, if people knew the risks of setting foot on Whakaari White Island, they wouldn't.
"People talk about visiting the island but the reality is the tourists were going into the crater of an active volcano. That is, an unpredictable volatile volcanic crater that had erupted as recently as 2016," WorkSafe lawyer Kirtsy McDonald KC said.
Meanwhile, the sheer power and force of the blast were caught by GNS monitoring cameras.
WorkSafe said the eruption on December 9 2019 resulted in a flow of burning ash, scalding steam, poisonous volcanic gases and rocks, travelling at 60 kilometres an hour and immersing the crater in less than two minutes.
"The burn injuries suggested the current reached temperatures of 100C, possibly more," McDonald said.
Whakaari is owned by the Buttle brothers, Peter, James and Andrew. Before the eruption, Peter and Andrew appeared in a documentary about the island.
"It's like you're entering a completely different world. It blows your mind in a way, the power of nature and the power of what you can feel when you're on the island," Peter said in the doco.
WorkSafe told the court the Buttles and their management company WML had no safety management system or other health and safety processes at all.
"WML was obliged to understand the risks of what it was doing. It never bothered to understand the risks properly," McDonald said.
But the Buttles were making good money from the island, demanding an annual licence fee from tour operators and taking a commission for every tourist who set foot on Whakaari. They were even exploring the possibility of glamping, the glamorous version of overnight stays there.
"By 2019, WML was making approximately $1m profit per year," McDonald said.
And little of that money was ploughed back into safety. Protection amounted to an inaccessible metal shipping container and as for evacuation, the 90-year-old wharf was in poor condition and corroding.
"The state of the wharf and the need to ferry injured persons in inflatable boats off Whakaari delayed the evacuation on the ninth of December and exacerbated the harm suffered by the victims," McDonald said.
Also charged are ID Tours and Tauranga Tourism Limited. They helped arrange visits for cruise ship passengers, but WorkSafe says passengers were never provided adequate information about the risks.
"The cruise ship passengers who were on Whakaari when it erupted received no health and safety information prior to commencing the tour," McDonald said.
WorkSafe accepts that the owners weren't experts in volcanic activity but as directors of the management company, they had a duty to employ experts to assess the risk.
But they didn't consult.
"That failure arose because the Buttles, the directors of WML, failed to exercise care, failed to exercise due diligence, failed to ensure that their company WML complied with its duties," McDonald said.
Twenty-two people died and 25 were injured in the eruption.
The Buttles have pleaded not guilty and strenuously deny the charges but will have to wait weeks before their lawyers get a chance to lay out their defence.
