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Earth deformation in relation to town planning in New Zealand

  • Lensen G. J. 
Symposium 113 Geological Hazards And The Environment

Summary

Earth deformation is shown to extend well beyond the planes of active faults, to vary with the nature of the tectonic regime; it is confined to a zone which varies in width from about 40 metres to several kilometres and is controlled by the development of secondary features.

Faults are classified into earthquake generating and earthquake generated faults. The latter are further separated into secondary shear features, bedding faults — both dip slip and strike slip — ridge rents, compaction faults and contact faults. Strike slip bedding faults can develop either as a result of shear or as a result of folding. The latter demonstrate a conjugate strike relationship with active faults and thus areas potentially prone to their development can be identified.

A range of active folds is discussed and illustrated.

The New Zealand Geological Survey classification of active faults and its application to town planning is discussed.

Keywords

Active Fault Tectonic Regime Fault Movement Town Planning Secondary Feature 

Conditions Tectoniques En Rapport Avec L’Aménagement Urbain A la Nouvelle Zélande

Résumé

On montre que les deformations tectoniques étendent sur quelque distance en dehors des plans de failles actives; également elles varient avec le caractère du regime tectonique, mais elles sont restreintes à une zone de 40 mètres à plusieurs de kilomètres, selon les développements secondaires.

Il y a deux types de failles: celles qui causent, et celles qui sont causées par, des tremblements de terre. Ces dernières sont encore subdivisées en cisaillements secondaires, en failles le long de la stratification — des composantes tant horizontales que verticales du rejet —, ”ridge rents”, en failles causées par la compactation differentielle et par le ”contact”.

Des rejets horizontaux peuvent être dus au cisaillement, ou bien au plissement. Ces derniers exposent une relation en directions conjuguées avec les failles actives: ainsi on peut distinguer des domaines où ces rejets horizontaux peuvent se former.

On discute, avec des illustrations, une série de plis actifs.

Finalement on discute la classification des failles actives utilisée par le Service Géologique de la Nouvelle Zélande et ses applications à l’aménagement urbain.

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Copyright information

© International Association of Engineering Geology 1976

Authors and Affiliations

  • Lensen G. J. 
    • 1
  1. 1.N.Z. Geological SurveyLower HuttNew Zealand

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