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The house where the explosion occurred - 9 Marble Court - was completely destroyed on July 19.
Nine homes were damaged when the sudden blast obliterated the Marble Court house, sending chunks of roof tiles and other debris over the neighbourhood.
One man was rushed to Christchurch Hospital where he was placed on life support. Five others were also taken to hospital.
Neighbours and passers-by pulled stunned survivors from the burning debris and were amazed nobody was instantly killed.
Charges have now been filed under the Gas Act 1992 against two defendants - an individual and a company.
The charges follow an investigation led by Energy Safety of Worksafe New Zealand, in consultation with the New Zealand Police, Fire and Emergency New Zealand and the Crown Solicitor’s office.
The first appearance will be on August 18 at the Christchurch District Court.
WorkSafe is unable to provide any further information on the case.
However, following the incident it was revealed a gas contractor had worked on the house, which was having gas issues, just one day before it exploded.
WorkSafe was working to determine "the immediate and underlying causes" of the event.
It said it has made efforts to contact all of the people affected by this incident but is asking anyone involved who has not been in touch with it to email email@example.com.
WorkSafe confirmed the matter would be heard in the Christchurch District Court.
"As this matter is currently before the court, WorkSafe is unable to provide any further information," WorkSafe said in a statement.
Kevin Smith, who was crushed in the debris and put in an induced coma for a month, spent about eight weeks in hospital. His wife Annette who was also hurt.
The Greymouth man and his wife were staying at his friends' Marble Court home when the massive explosion happened.
Paddy Blanchfield, Smith's son-in-law told the Herald on Sunday late last year they had been "battling" away with their injuries.
Smith suffered severe upper body burns and needs skin grafts.
"That's how bad he was. He has had a lot of skin grafts going on. Kevin was burnt in his lungs, his arms and his face- his whole upper body. Annette has had superficial wounds that didn't require skin grafts and has healed up pretty well physically. They are both traumatised. Old people can't deal with this stuff," Blanchfield said.
"They will never be the same again. This explosion has shortened their lives, they are all psychologically affected by what's happened."
Neighbours and passers-by who pulled stunned survivors from the burning debris were amazed that nobody was killed instantly.
The man and five others were rushed by ambulance to hospital.
At the time of the near-tragedy, neighbour Bradley Culver told the Herald he was having a cup of coffee and watching the Open Championship golf on TV with his wife when the explosion happened.
The former police officer ran outside and saw a neighbour's house completely destroyed.
He came to the trapped survivors' rescue.
They were stunned, he said, hardly able to talk.
"I am surprised nobody died [instantly]," Culver said.
"As a former police officer I've seen a lot in my days, but I've never seen anything like that."
The blast sent roof tiles, glass, wood fragments and pink insulation material flying into the air and raining down across several streets.
Fire and Emergency NZ area commander Dave Stackhouse also told the Herald at the time of the explosion that all of Northwood was connected to piped gas, but it was not immediately clear how there had been a leak.
"We've got our gas experts having a look at that," he said.
"Once we've got the scene safe, we'll look at what's caused this and carry out an investigation with police and WorkSafe."
Stackhouse said it was "probably lucky" the house inhabitants were close to the source of explosion when it happened.
"Often with these types of things it's the blast wave that can actually kill people further away from the actual radius of the initial explosion," he said.
"So I guess we are lucky that we are not looking at multiple fatalities here."
- Additional reporting Matt Slaughter and NZ Herald