Liquefaction in the Buller region in the 1929 and 1968 earthquakes

This article describes the results of a search for sites of liquefaction in the 1929 M=7.6 Murchison and the 1968, M=7.1 Inangahua earthquakes in the Buller region of New Zealand. Evidence of liquefaction was found for nine sites in each earthquake; two sites were common to both events. Widespread ejection of sand occurred in the epicentral regions of both earthquakes. Liquefaction was more sporadic at larger epicentral distances, except in the North Beach area of Westport, the most distant 1968 site, where sand boils occurred over several hectares, together with the toppling of utility poles and some lateral mass movement. This area corresponded to the very young beach sands deposited since extension of the Westport harbour breakwaters towards the end of last century. Liquefaction was much less common in the river-lain sands in the same vicinity.