Description: The extracted QMAP 'NZL_GNS_250K_faults' dataset was modified by the addition of three new attribute fields, the repositioning of some faults or parts of faults, and the addition of new faults. The three new attribute fields are:ORC_nameCertaintySurf_formThe 'ORC_Name' field provides a local name for the mapped feature(s). The 'Certainty' attribute indicates the assessed level of the certainty with which each feature is recognized as an active fault (definite, likely or possible) or as a potentially active fault. The 'Surf_form' (Surface form) attributes provides an interpretation of the surface distinctiveness of each feature at the ground surface (well expressed, moderately expressed, not expressed, unknown). A single active fault at depth is commonly expressed at the ground surface as a zone of splintering. An individual line of splinters (fault strand) may comprise fault offsets of the ground surface (fault scarps) or ground-surface folds (fold scarps), and typically a mixture of both. A fault zone may include several lines (traces) of semi-parallel strands and a fault zone can in some cases be several kilometres wide. Some strands have previously been named separately, and this name is retained in the GIS dataset, but the various strands that comprise an active fault are grouped under a common name (ORC_name). This is done to highlight that, collectively, the strands are regarded as part of a single active fault structure, whose movements at depth have produced an array of ground-surface fault and/or fold deformation.The QMAP 'NZL_GNS_250K_faults' dataset contains many attribute fields that are not important for the dataset described here, and those fields have been deleted from this dataset, except for the 'DOWN_QUAD' field. The DOWN_QUAD indicates the relative direction of fault movement, by stating which side of the fault is downthrown (e.g., north, northeast, east, southeast, south, southwest, west, northwest).Where an active fault has surface expression (i.e., is marked by a fault scarp), the line denoting its location is positioned along the middle to lower part of the fault scarp. This is of no practical significance where the scarp is relatively small (e.g., several metres high), but is more significant where the scarp is large (e.g., tens of metres high) and therefore has notable width in map view. Where a fault is assigned a Surf_form attribute of 'not expressed', its location is an inference, based on extrapolation or interpolation from adjacent sectors where the fault does have ground-surface expression. Unless indicated otherwise, all the fault data have been compiled at a regional scale (1:250,000) and the locations of active and potentially active faults in the 'Clutha_Dunedin_active_faults_September2020' feature class should be regarded as having a general accuracy of ± 250 m, and at best, ± 100 m. The geographic coordinate system for the data is New Zealand Geodetic Datum 2000.
Copyright Text: Modified dataset compiled by D.J.A. Barrell. Data described and documented in:
Barrell, D.J.A. 2020. General distribution and characteristics of active faults and folds in the Clutha and Dunedin City districts, Otago. Lower Hutt (NZ): GNS Science. Consultancy Report 2020/88.
Original source reference:
Heron, D.W. (custodian) 2018. Geological map of New Zealand 1:250,000 (2nd edition). Lower Hutt (NZ): GNS Science. 1 USB. GNS Science Geological Map 1