A Queensland mining specialist has told the Pike River Royal Commission that while it is impossible to be definite about the cause of the 2010 tragedy, the mine fell short on health and safety in at least 10 areas.
The commission is now looking at the immediate causes of the explosions that killed 29 men in November 2010.
David Reece on Thursday listed deficiencies in safety including gas drainage, machine maintenance, ventilation and the monitoring of gas.
However, Mr Reece said it is impossible to be definitive about the cause of the explosion.
An investigation by the Department of Labour has found the most likely cause was a sudden release of methane ignited by sparks from an electrical fault.