Why the body of a coalminer showed no sign of damage from the massive explosion that tore through the Pike River Mine was one of two enduring puzzles scrutinised at the Royal Commission of Inquiry into the disaster today.

This week, the commission heard the explosion was possibly the result of a collapse in the 'goaf' - the area already mined - which sent explosive gases racing through the mine at the same time as the water pumps were turned on, re-powering the electrical system, which possibly began sparking and arcing.

Australian mining expert David Reece, one of five used by the Department of Labour in its investigation, was asked today why underground camera footage of some parts of the mine showed relatively little damage.

He said the position of the body suggested there had not been a "degree of violence" in that part of the mine; instead, he was probably overcome by gases as his body appeared "relaxed".


The force of the blast was elsewhere, as the goaf gases would have travelled before hitting an ignition source.

The miner had possibly gone to see if the air flow barrier had survived the wave of gases being pushed out from the goaf collapse - then the mine exploded.

Mr Reece also discussed another puzzle - footage of a rag pulsing in the two minutes before the blast. He said a wide range of people had spent many hours trying to explain it.

"There wasn't a lot of agreement ... (but) it struck me potentially there might have been a slight suck-back, potentially due to some goaf (collapse)."

The families want a borehole drilled into the goaf area, to see if it collapsed as suspected.

Goafs are meant to collapse but Mr Reece said the ventilation devices to remove the released gases were inadequate. Pike River could also have used early warning systems.

Former chief executive Peter Whittall's lawyer Stacey Shortall said several miners told investigators they had witnessed one of the men who died using the compressed airline to blow fresh air over machine sensors.

One interviewee alleged he had seen three of the men who died override safety features, she said.

That could give weight to the theory a diesel machine caused the blast, possibly by overheating.

The inquiry will resume on Monday morning.

Meanwhile, a trust will be formed to oversee the recovery of the 29 men still entombed in the Pike River Mine but Grey District Mayor Tony Kokshoorn said today it would not hasten the process.

Mr Kokshoorn was in Wellington yesterday to meet with Prime Minister John Key, National Party list MP Chris Auchinvole and Pike River Coal Ltd receiver John Fisk to discuss the trust proposition.

Today, Mr Kokshoorn said the trust idea had support from the Government and receiver.

"Both agreed to invest financially in the trust.''

However, he said none of that would speed up the body recovery, which would not begin until the mine was in the hands of new owners.

Representatives of the victims' families also needed to "buy into'' the trust idea.

Mr Kokshoorn said forming the trust was "a way forward''.

"The development of a trust means that when the mine has new owners, the trust will work alongside the owners with the aim being to recovery the bodies.''

The make-up of the trust has yet to be decided, but it would include skilled, professional people who would help "nut out'' a recovery plan.

"Ultimately the aim of the trust is, with their best endeavours, to recover the bodies.

"Once you get over one hurdle there is another one to leap, just around the corner ... but it feels like we are going forward,'' he said.