ABSTRACT
A rock avalanche of 100,000 m3 occurred in a glacial valley in the Southern Alps of New Zealand in 2002. Occasional rockfalls and rock avalanches occur in the schist, typically on slopes over-steepened by glacial or fluvial erosion. This chapter is concerned with a small rock avalanche of approximately 100,000 m3 that occurred on alpine slopes above the Haast Pass Highway on the shores of Lake Wanaka in 2002. The rock avalanche site is located in the Southern Alps 45 km east of the Alpine Fault, the boundary between the Australian and Pacific tectonic plates. The rock avalanche was not directly observed, but a motorist driving along the Haast Pass Highway saw boulders falling onto the road and raised the alarm. Because of the risk of further rockfalls, the highway was immediately closed. The rock avalanche is thought to have resulted from a rapid sliding failure of a weakened mass of toppled schist.
