Jim O'Donnell helped drag his dead mates out of the Strongman mine in a marathon rescue.

Families grieving after the Pike River disaster have called on a lawyer who rallied for victims in a previous West Coast disaster.

Large amounts of smoke and flames are coming from the Pike River Coal mine after a fourth, powerful explosion today and boss Peter Whittall says it may have to be temporarily sealed.

The Prime Minister and Governor-General will speak at a memorial for the 29 men who died in the Pike River Coal mine.

The Pike River blast has led some miners to discuss whether it is safe to remain in the industry.

Leigh Hart, aka That Guy, shares a very personal account of how mining disasters can affect families.

An NZ Mines Rescue member wants the public to understand what the rescue team members are going through.

Broadcaster Maggie Barry, whose cousin Michael Monk was lost at the Pike River mine, understands when people asked counsellors "funny" questions.

A trip to the Pike River coal mine provided a sense of closure for some of the lost miners' relatives.

"What gave armchair critics the right to criticise and worse - accuse the rescuers of deliberately sitting on their hands?"

Up to 500 relatives and friends of the Pike River miners travelled to the mine today, which one mother described as "very healing".

Grey District Mayor Tony Kokshoorn wants the mining industry to learn from past mistakes and has called for a royal inquiry.

"We pray that their moment of fear becomes eternal peace," said Monsignor Gerry O'Connor during an emotional tribute to the Pike River miners in Greymouth.

Families of the dead men due to be bused to the Pike River mine tomorrow will still go, despite a third explosion at the mine this afternoon.

There has been a third explosion at the Pike River mine this afternoon. The blast occurred at 3.39pm and lasted for 23 seconds.

A third robot that has gone 1575m into the Pike River coal mine has detected debris and destruction indicating Wednesday's blast was much more violent than the first one.

It is likely to be several more days before operations will start to stabilise the Pike River mine so that the bodies of 29 men can recovered, police say.

A Pike River Relief Fund Trust has been established for the families of the 29 men who died in the Pike River coal mine.

A small West Coast community will now face the task of recovering and rebuilding following a disaster of devastating proportions.

International experts say they are shocked a mining disaster the magnitude of the Pike River tragedy occurred in a modern mine.

Liquid nitrogen could be used to stabilise the situation in the Pike River mine, experts told the Science Media Centre.

He has to accept he has lost a son. But Marty Palmer won't give up until his son's body is back with the family so they can mourn properly.