Explosives for Ice Blasting (Alex Pyne).

Explosives have been used previously by NZARP events working on the sea ice. The main uses have been for seismic studies or to make access holes in sea ice to sample the sea water and sea floor. It was for both these purposes that members of Event 14 participated in an explosives course, arranged through the Department of Labour (Explosives Division), prior to departing for Antarctica.

In previous seasons sea ice thickness has been quite variable. In open parts of the Sound it is between 2 and 3m, but in a few places, notably Explorers Cove and the bay at Ferrar Glacier Snout in New Harbour, the ice has been up to 5m thick because it is several years old. The VUWAE portable motorised 12 inch diameter auger was not expected to penetrate overthickened ice so explosives were to have been used to complete the access holes. This season, however, nearly all the sea ice in the Sound was first-year ice a little over 2m in thickness, which was well within the auger's capability. Consequently, no explosives were used to make sea ice holes but were used for the seismic refraction programme and to blast the Scott Base ice quarry.

The explosives were obtained from the US Navy Support Force stores at McMurdo Station and will be partly replaced by stock donated to the expedition by ICI NZ Ltd. The ICI stock will be used by next year's expedition continuing the work on the sea ice. Electric detonators were not available from the McMurdo stores so plain No.6 detonators initiated with safety fuse were used. Plain detonators were considered to be the much safer option in antarctic conditions where static electricity is frequently developed in the dry air and from blowing snow. A reinforced detonating chord (10g/m P.E.T.N.) was used to initiate the main charges of either AN GD 95 or a 60% seismic grade gelignite.