The prosecution of 13 parties over the Whakaari/White Island tragedy has been adjourned to next year but details of the case can be revealed as court documents have been released.
There were 47 people on the island at the time of the eruption last year - 22 of whom lost their lives.
When WorkSafe chief executive Phil Parkes first announced the charges he said it concluded their most extensive and complex investigation.
As a result, 19 charges were laid under the Health and Safety at Work Act 2015 in the Auckland District Court.
Ten organisations have been charged, and three individuals.
All organisations are charged in a way that alleges failure to ensure health and safety so far as "reasonably practicable" and that the failure exposed people "to a risk of death or serious injury arising from volcanic activity".
White Island Tours faces two charges related to alleged offending between April 2017 and December 2019.
Two White Island Tours guides, Jake Milbank and Kelsey Waghorn, were seriously injured in the disaster. Fellow guides Hayden-Marshall Inman and Tipene Maangi lost their lives.
One charge against the company relates to its duty to workers and the other relates to its duty to tourists.
In relation to tourists, the charge particulars alleges it was reasonable to: "Ensure booking confirmation, pre-activity information and tour description information provided sufficient detail regarding the hazards and risks, including the risks posed to tourists from volcanic activity, so tourists so could make an informed decision prior to commencing the tour."
Whakaari Management Ltd faces two charges related to alleged offending between April 2016 and December 2019.
The company granted licences to the operators that undertook tours to the volcanic island.
In the particulars of both charges it alleged it was reasonable to ensure that workers and tourists were supplied with "appropriate personal protective equipment".
Whakaari Management Limited's three directors - James, Peter and Andrew Buttle - each face one charge respectively.
It is alleged that each, as an officer of Whakaari Management Ltd, failed in the duty to exercise due diligence to ensure the company was meeting its health and safety obligations.
Kahu NZ faces two charges related to alleged offending between April 2016 and December 2019.
One charge relates to the health and safety of workers and the other to the health and safety of tourists.
Kahu Helicopters director Mark Law is one of the pilots who helped rescue people from Whakaari after the eruption.
Law rescued five people from the island.
A fellow pilot, John Funnell, had set up a fund to raise money to help with the legal battle, RNZ said.
Law posted on Facebook last night that he wanted to acknowledge the New Zealanders and Australians who had reached out in support of him, the company and others.
He called the support "humbling and hugely appreciated".
The enormous support showed the desire for fair investigation, the post read.
"I am sure that this process will help the families clearly understand every aspect of tourism operations to White Island."
WorkSafe has previously confirmed it did not investigate the rescue and recovery of victims after the eruption. On those matters, no enforcement action has been taken.
The National Emergency Management Agency (formerly Civil Defence and Emergency Management) is also facing a charge for alleged offending between April 2016 and December 2019 at Whakaari/White Island.
The agency provides leadership in reducing risk, being ready for and responding to and recovering from emergencies.
The Institute of Geological and Nuclear Sciences (GNS), Volcanic Air Safaris, and Aerius Ltd face two charges each.
GNS Science monitors volcanic activity in this country, including White Island, and scientists assign an alert level for each volcano.
Three other organisations have also been charged, but as they have not publicly identified themselves the Herald will not name them before a first appearance in court for legal reasons.
For all organisations on each charge the maximum penalty is a fine of $1.5 million.