Effects of microzoning and foundations on damage ratios for domestic property in the magnitude 7.2 1968 Inangahua, New Zealand earthquake

In a recent study the present authors examined the damage ratios for houses and household contents in the Inangahua earthquake for intensities MM5-MM10, including the effects of chimney damage. The present study continues this work by examining the effects of ground class and construction type on damage levels. Houses from six towns are considered, i.e. Inangahua, Reefton, Westport, Greymouth, Runanga and Hokitika, covering a range of intensities from MM10.5 down to MM7.0. A range of ground classes is also considered, covering the three classes described in the New Zealand loadings standard. The structural types considered comprise two foundation types (piled vs. concrete perimeter wall footings), and number of storeys. Some complexities and difficulties of reliable microzoning are revealed and discussed.

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