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Greywacke-type basement rocks from tunnels and other excavations along the western part of the Kaimanawa Range (eastern diversions) and in a buried sequence cut by the WhakapapaTawhitikuri tunnel (western diversions) comprise mainly sandstone, siltstone, and argillite, but chert and minor basaltic rock and limestone are also present in the Kaimanawa Range. Rocks of the latter are comparable with Torlesse terrane sequences elsewhere, whereas the Whakapapa-Tawhitikuri tunnel rocks have contrasting petrography and structural style and belong to the younger Waipapa terrane, forming part of the Morrinsville facies. Petrographic, modal, and chemical data show that the Torlesse rocks are more siliceous and contain abundant granitic debris; the Waipapa terrane rocks are considerably less siliceous, and typical sandstones have a high content of intermediate volcanic clasts. Among the Kaimanawa Range rocks, complexly intermixed units, involving sandstone, siltstone, argillite, and chert, approach typical melange. All Kaimanawa Range rocks show pervasive recrystallisation, and in fabric most range from textural zone 1 to 2A. Siltstone and sandstone of textural zone 2B cover only comparatively small areas. They are characterised by steeply dipping lineation and poorly developed schistosity and are classed as semischist. Fissility is marked in associated argillites. The formation of the melange and associated features recorded is probably the result of severe shearing and imbrication during the Rangitata Orogeny.

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This paper describes the analysis of a large data base of actual costs of damage to houses in Napier in the magnitude Ms = 7.8 Hawke's Bay earthquake of 1931. This event occurred prior to the introduction of any earthquake design regulations in New Zealand. The town of Napier was sited over the source of this large shallow event, and therefore it may be presumed that it was subjected to about the strongest shaking likely to occur in an earthquake. Mean values and statistical distributions of damage ratios have been estimated for houses built on rock, on firm beach deposits, and on soft recent alluvium. This is the first time world-wide that a fully representative quantification of damage has been made for a zone of such strong earthquake shaking, for any class of construction, with or without quantification of microzoning effects. This study examines the damage to housing due to ground shaking and ground damage, and excludes the effects of earthquake-induced fires.

Physical modelling of part of prehistoric Waikaremoana landslide shows that the blockslide must have hit the valley wall at c . 40 m/s, after sliding 2 km on a 5.5–8° slope, in order to form the 150-m high mound of debris known as Raekahu. Both the blockslide and a distal rock avalanche were in simultaneous motion when the impact occurred. Finely ground rock on the slide plane suggests that a mechanism of dynamic rock fragmentation may explain the low friction necessary for acceleration to 40 m/s. When a rock particle fractures in a confined space, an isotropic dispersive pressure equal to the rock's Hugoniot elastic limit (in the GPa range) at the ambient pressure and strain rate may be exerted on its surroundings. Beneath the 275-m thick block, about one particle in 15–30 or so fragmenting at any instant (with lower density for higher rock strength at higher strain rate), could completely support the weight of the block by fragmentation pressure; but then there would be no frictional resistance (and hence no further fragmentation). Self-regulation of the process may explain the apparent coefficient of friction of c . 0.1 in the blockslide. Low friction through dynamic fragmentation may apply widely to blockslides with a basal layer of comminuted rock.