Fourth blast at Pike River mine

The entrance to the Pike River Coal. Photo / APN

Another explosion rocked the Pike River Coal mine near Greymouth shortly before 2pm today.

There were no injuries from today's explosion and people working near the entrance to the mine were moved away from the area for their safety.

Superintendent Dave Cliff said the latest explosion demonstrated the volatility of the environment surrounding the mine.

"Our focus continues to be on the safety of those people working at the mine site and the recovery team.

"We are doing all we can to progress the recovery operation, however the explosion reinforces the risks involved in working in this environment and the requirement to put people's safety first."

NZPA was told that today's explosion blew away some of the infrastructure on top of the shaft.

Grey District Mayor Tony Kokshoorn confirmed this to TV3, saying the entire ventilation shaft had shifted.

"[Damage] was significant this time around."

But he said this would not delay or hamper progress.

An Australian jet engine, called a gag, arrived at Hokitika this morning.

The "gagging" process would likely begin on Monday morning, he said.

This involves displacing the air underground with nitrogen and carbon dioxide to remove any oxygen present.

As combustion cannot occur without the presence of oxygen, the process puts out any fires still alight and removes the risk of another explosion.

Police re-evaluating options

Flames could be seen coming from the shaft during today's blast.

Officials said it appeared they were dealing with a coal fire and not a gas fire as was initially thought - and they might need to seal off the mine to snuff out the blaze.

Inspector Mark Harrison, officer in charge of the recovery phase of Operation Pike, says the explosion was significant and was fuelled by methane, as the previous three have been.

"It literally sparked a coal fire in the mine. The fire is visible from the air above the ventilation shaft which was further damaged during the latest explosion."

A small area of vegetation near the damaged shaft caught fire but has been extinguished.

Up to 180 people at times have been on site working on the recovery mission, but he said today's blast had caused police to reconsider their options.

He said they were relying on mining experts and Pike River itself for information to determine the safest course of action.

"Given that there is a significant coal fire burning in the mine, all our options for recovery are being re-evaluated."

Royal inquiry proposed

Meanwhile, Prime Minister John Key has called for a Royal Commission of Inquiry into the disaster.

He said it would demonstrate to families of those killed how seriously it was being taken.

Speaking on Q&A this morning Mr Key said Cabinet would tomorrow consider his proposal for the high level inquiry.

"I think it's a demonstration to the 29 families that we are taking this inquiry absolutely seriously, that we are determined to get answers for those families and that we will leave no stone unturned," he said.

EPMU national secretary Andrew Little said the union backed the proposal.

"The inquiry should also enable the bereaved families to attend proceedings and be represented."

He said the EPMU had started to assemble an international team of legal and technical experts and "will do all it can to assist the inquiry".

"The scope of the inquiry needs to include the specific causes that led up to the fatal explosions in the mine, the subsequent rescue and recovery operations, and the broader safety and regulation of underground mining in New Zealand.

"The families of the 29 men killed and the wider mining community on the West Coast deserve nothing less."

He added: "The Commission will need to make recommendations to the government on the future of the mine, including its safe operation if it resumes production following this tragedy."

- NZPA, NZHERALD STAFF