What happened and why at Pike River

Superintendent Gary Knowles, who headed up the Pike River mission. Photo / NZPA

How many hours passed before the miners were pronounced dead?

Almost 119 hours passed before families were told that there was no hope any of their loved ones were still alive. The initial blast happened on Friday at 3.45pm. Yesterday's second explosion happened at 2.37pm.

What kind of blast was the initial explosion?

It was a methane gas explosion. Experts believe it was caused by a build-up of methane gas and/or coal dust.

What caused the second explosion yesterday?

Similar to the initial blast. Authorities said air sampled after drilling into the mine during the rescue mission contained high levels of carbon monoxide and methane, and that triggered the explosion yesterday.

Why didn't rescuers enter the mine immediately after the initial explosion on Friday?

Rescue efforts were hampered as authorities feared another explosion could happen. Police did not want other lives put at risk.

How many robots had been sent into the mine before the second explosion occurred?

Two robots - a Defence Force machine and an Army one - had been sent inside. Earlier yesterday, one of the robots found a miner's hat - believed to belong to Russell Smith, one of the two survivors. A third robot from Western Australia arrived on the West Coast yesterday and was set to enter the mine also.

What equipment would miners have had on them?

The men would have had high-visibility gear, a battery-powered lamp, a lamp battery, a self-rescue breathing apparatus that produces oxygen, steel-capped waterproof boots and gloves.

Is it likely there were any survivors after the initial blast?

Mine safety experts said yesterday that the chances were that the miners had not suffered and had been overcome by carbon monoxide after the initial explosion.

Were the miners together?

They could have been in as many as four groups. However, there is a possibility that there could have been some who were alone. Russell Smith and the other survivor, Daniel Rockhouse, were both alone when the first blast occurred.

Will the 29 bodies be recovered?

Authorities will be working to purge the mine of dangerous gases before the emergency services look to bring out the dead miners.