Citation

Lee J, Davies T, Bell D. Landslides 2009; 6(4): 287-297.

Copyright

(Copyright © 2009, Holtzbrinck Springer Nature Publishing Group)

DOI

10.1007/s10346-009-0163-6

PMID

unavailable

Abstract

At Lake Coleridge, Canterbury, New Zealand, at least three rock avalanches have been released from a single source area during the Holocene. The first of these was of 10 7 m 3 volume and dates to about 9,750 BP, and two with volumes 5 × 10 5 and 4 × 10 4 m 3 occurred about 700 BP. All three crossed the course of the Ryton River; the latter two were emplaced within the part of the first that had subsequently been eroded by the Ryton River. All three were most likely triggered by, or related to, seismicity. The first rock avalanche formed a long-lived landslide dam, and no evidence remains to indicate whether its eventual failure was catastrophic. The second formed a correspondingly smaller dam, but there is no evidence that its lake was long-lived; however, a set of anomalously steep outwash terraces downstream of the landslide deposits show that it failed catastrophically. A camping ground is sited about 1 km downstream of the landslide deposits, and proposals to develop it further risk potentially severe hazards from future rock avalanche activity at the site.