Identification of alluvial fans susceptible to debris-flow hazardsAbstract We describe and test a method for identifying alluvial fans likely to be affected by debris flows. It is based on identifying catchment parameters by geographical information system interrogation of a digital elevation model, using the Melton ratio as the discriminating parameter. The method was calibrated using data from debris-flow-generating catchments in Coromandel and the adjacent Kaimai Ranges, North Island, NZ, and tested against data from the rest of New Zealand. The procedure is remarkably (but not completely) reliable for identifying debris-flow-capable catchments, and thus fans, across the wide range of climates and lithologies in New Zealand mountains. A case study illustrates the potential of the method for avoiding future hazards and emphasises the need for a precautionary approach when field investigations do not detect evidence for past debris flows.

A GPS network has been installed to monitor vertical crustal movement in the Lambert Glacier region, East Antarctica. The program commenced in January 1998 with a solar-powered GPS system installed at Beaver Lake. Solar-powered observations were also made late in the Antarctic summer of 1999. In January 2000, two new solarpowered sites will be installed to expand the monitoring network. In addition, we will be installing a hydrogen fuel cell power system at Beaver Lake to enable the equipment to operate throughout the winter months when solar power is not available. In this paper we outline the equipment which has been developed in order to operate remote GPS equipment in Antarctica, provide predictions of the expected rate of rebound and comment on preliminary results from the data collected to date.

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Ore grades are monitored regularly in cave mines through drawpoint sampling. Automating grade monitoring through deploying X-ray fluorescence (XRF) sensors on the buckets of production loaders has been proposed as an alternative approach to address the issues around the traditional practice of drawpoint sampling. Bucket-mounted sensors can also be employed for bulk ore sorting underground. This study is aimed at evaluating the deployment of XRF sensors on production loaders as an opportunity for grade monitoring or bulk ore sorting in caving operations. The mill feed grade prediction performances of the drawpoint sampling program and mine planning software were assessed for the Cadia East panel cave mine. The results showed that the drawpoint samples underestimated the mill feed quality during a 10-month investigation period. The cave portions with bulk ore sorting potential were linked to the extraction level layout to estimate the number of drawpoints where sensors could be situated for diverting ore and waste. Samples obtained from the mine were tested to evaluate the ability of a lab-scale proxy of a bucket-mounted XRF sensor system to measure copper and gold grades. R-squared values of 0.84 and 0.68 were achieved between the predicted and measured copper and gold grades of the samples, respectively. Sensor test results are promising in revealing the potential to utilize XRF sensors underground. Future test work is encouraged to further validate the applicability of XRF sensors in an underground mining environment.