Australian lawyers - who Whakaari eruption victims have hired to sue cruise line Royal Caribbean - are now investigating suing White Island Tours too.
In April, Sydney-based firm Stacks Goudkamp confirmed it was pursuing legal action, on behalf of some passengers and their family members, against the cruise line.
Now,six months on from the tragedy, NZME can reveal the victims' lawyers are also considering legal action against White Island Tours.
"Whether White Island Tours can be seen as actually conducting business in Australia - that's a key question for us in terms of whether we can pursue them in addition to Royal Caribbean," Stacks Goudkamp lawyer Rita Yousef said.
"Booking with them [White Island Tours] through an Australian travel agency, for example, would potentially be proof of conducting business here [in Australia].
"My focus is looking at how the Australian Consumer Law gives people who are injured or who lost loved ones rights against this company, if it was conducting business in Australia."
In New Zealand, police are investigating the Whakaari deaths on behalf of the Coroner.
There are now 27 WorkSafe staff - 10 based in Whakatāne - working on WorkSafe's investigation. Penalties and criminal sanctions range from $50,000 to $3 million and up to five years in prison for breaches of health and safety law.
"If the findings are that they [White Island Tours] conducted themselves inadequately, then absolutely I believe they should be fined," Yousef told NZME.
She said it was too early to say how much compensation victims could be entitled to.
"One of the avenues that's available is a claim for what's called nervous shock - for either witnesses or close family members who are affected by what's happened to the primary victims [those injured on the island]."
Yousef said many components would contribute to any lump compensation sum.
"There's the pain and suffering which is all about the severity of the injuries and the impact on lifestyle and ongoing disabilities ... There's lost wages both in the past and in the future and lost capacity for work.
"There's future and past out-of-pocket expenses - so treatment expenses and associated expenses - and then there's care and assistance both past and in the future, as well as components like equipment expenses."
A White Island Tours spokeswoman said it would be inappropriate to comment while investigations were ongoing.
Involving White Island Tours means victims 'don't lose out'
Preliminary moves to take potential legal action against White Island Tours were "not a surprise" to Dr Michael Eburn, an Honorary Associate Professor at the Australian National University's College of Law.
"Joining them both [Royal Caribbean and White Island Tours] in the action avoids the problem of suing one defendant and them saying 'responsibility for that decision was with the other; who isn't here'."
He said even if the companies blamed each other the court could apportion responsibility if there was responsibility to apportion.
Stacks Goudkamp lawyers would have "no problem" retrieving information to determine whether White Island Tours was practising business in Australia, Eburn said.
"White Island Tours would have annual reports and public documents and documents can be subject to court orders for production ... There are processes to allow a court order made in one country to be registered with the court in another country and then enforced."
However, "there's a long way to go before anyone could be confident that the plaintiffs will win", he said.
''There are many areas here that will pose a problem. The tourists knew they were going to a volcano and under New South Wales law - which is the same or similar to all states and territories - there is no duty to warn of obvious risks and liability may have been waived," Eburn said.
Professor Jeannie Paterson, from the University of Melbourne Law School, said if there was Australian legal action against White Island Tours, "much will depend on the outcome of the Coroner's findings".