Citation

Chevalier G, Davies T, McSaveney M. Landslides 2009; 6(3): 253-262.

Copyright

(Copyright © 2009, Holtzbrinck Springer Nature Publishing Group)

DOI

10.1007/s10346-009-0156-5

PMID

unavailable

Abstract

The Mt Wilberg rock avalanche in Westland, New Zealand occurred before 1300 AD and may have occurred as a consequence of an Alpine fault earthquake in ca. 1220 AD or earlier. Its ∼40 × 10 6 m 3 deposit may have briefly obstructed the Wanganui River, but only about 25% of its surface morphology still survives, on terraces isolated from river erosion. The landslide appears to have moved initially as a block, in a direction controlled by a strong rock mass at the base of the source area, before disintegrating and spreading across terraces, fans, and floodplains. Rock avalanche deposits in Westland have relatively short expected lifetimes in the rugged terrain and high rainfall of the area; hence, the hazard from such events is under-represented by their current remnants.