Some family members of the 29 victims are calling for the Government to assess going past the roof fall at the top of the drift to recover evidence from the mine’s main ventilation fan, which could hold clues about what caused the first explosion in November 2010. NZ Police The Pike River mine after the explosion in 2010. The mine’s geotechnical strata was “inherently unstable” and the technical challenge of getting past a roof fall blocking the mine workings would be phenomenal, he said. Pike River father Bernie Monk said international mining and ventilation experts had told him it was possible to recover the mine’s fan only 30m from where the recovery team stopped at the top of the drift.