Seismic

Multifold, normal-incidence seismic measurements were made along two, 10km profiles in the New Harbour region (Fig. 2) and one 19km line in the McMurdo Ice Shelf (Fig. 3). The data were recorded on a 48-channel Bison digital recording seismograph (On loan from the British Antarctic Survey). Shots, 1 every 100 m, consisting of 1.2 kg (3 × Anzomex PPP Primers) and 3.2-4.0 kg (8-10 × Anzomex PPP Primers) of explosive were placed at 5m below sea-ice in New Harbour and 18m depth in the ice shelf. 40 Hz geophone receivers will be placed every 50-m to give a 12 fold geometry for the profile. Shots were placed in front of the spread in off-end geometry with an offset range of 100 to 2450 m. Geophones were drilled into the sea-ice to ensure effective coupling. Shot hole drilling operations carried under contract by Webster Drilling and Exploration with supervision provided by Alex Pyne (VUW). Differential GPS was used for shot point and peg surveying. Preliminary processing was carried out in the field and more detailed processing will be undertaken back at Geological and Nuclear Sciences using Claritas software and Oxford University using Promax software. Processing of the ice shelf line will form part of a Natalie Balfour's B.Sc.(hons) dissertation at VUW, and will be supervised by Stephen Bannister at GNS. Acquisition and processing parameters are summarised in a preliminary report (Bannister and Naish, 2001). Procedures utilised involve muting noisy traces, optimum filter and deconvolution parameters will be chosen following tests on interactive displays of shot records. Pre-stack traces balanced using AGC. Velocity analysis by constant velocity stack.