WorkSafe has filed charges following an investigation into a gas explosion in a house in Marble Court, Northwood, Christchurch.

Nine homes were damaged when a sudden blast obliterated a Marble Court house in the northern suburb of Northwood in July last year, sending chunks of roof tiles and other debris over the neighbourhood.

Neighbours and others who raced to the aid of the six people inside at the time were amazed that no one was killed. One person was critically injured in the incident, another suffered serious, and others minor injuries.

Shortly after the explosion, a gas contractor who had worked at a house the day before arrived at the chaotic scene and made himself known to police officers.

The gas worker spoke to first responders at the scene and voluntarily made himself known, suggesting that police or fire investigators might want to talk to him.
He was devastated by what happened, sources told the Herald.

It was understood the residents of the home had been having trouble with their gas fire.

WorkSafe revealed today that charges have been filed under the Gas Act 1992 against two defendants following the incident in which a gas explosion caused serious harm to several individuals, destroyed a house and caused significant damage to several other properties in the neighbourhood.

The charges come after an investigation led by Energy Safety of Worksafe NZ, in consultation with the New Zealand Police, Fire and Emergency New Zealand and the Crown Solicitor's office.

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.

A victim of the explosion was left fighting for his life after the giant blast.

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 in the northern Christchurch suburb of Northwood 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.

Witness amazed no one was killed

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 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."