General distribution and characteristics of active faults and folds in the Kaikoura District, North Canterbury Report No. R15/23 ISBN 978-0-478-15131-2 (print) 978-0-478-15132-9 (web) Report prepared for Environment Canterbury by DJA Barrell GNS Science March 2015 Report No. R15/23 ISBN 978-0-478-15131-2 (print) 978-0-478-15132-9 (web) PO Box 345 Christchurch 8140 Phone (03) 365 3828 Fax (03) 365 3194 75 Church Street PO Box 550 Timaru 7940 Phone (03) 687 7800 Fax (03) 687 7808 Website: www.ecan.govt.nz Customer Services Phone 0800 324 636 This report represents advice to Environment Canterbury and any views, conclusions or recommendations do not represent Council policy. The information in this report, together with any other information, may be used by staff to guide the design and review of monitoring and investigations programmes. General distribution and characteristics of active faults and folds in the Kaikoura District, North Canterbury D. J. A. Barrell GNS Science Consultancy Report 2014/210 Environment Canterbury Report R15/23 March 2015 DISCLAIMER This report has been prepared by the Institute of Geological and Nuclear Sciences Limited (GNS Science) exclusively for and under contract to Environment Canterbury. Unless otherwise agreed in writing by GNS Science, GNS Science accepts no responsibility for any use of or reliance on any contents of this Report by any person other than Environment Canterbury and shall not be liable to any person other than Environment Canterbury, on any ground, for any loss, damage or expense arising from such use or reliance. The data presented in this Report are available to GNS Science for other use from March 2015. BIBLIOGRAPHIC REFERENCE Barrell, D. J. A. 2014. General distribution and characteristics of active faults and folds in the Kaikoura District, North Canterbury, GNS Science Consultancy Report 2014/210. 59 p. © Environment Canterbury Report No. R15/23 ISBN 978-0-478-15131-2 [HARD COPY] ISBN 978-0-478-15132-9 [WEB COPY] Project Number 440W1481 2015 CONTENTS EXECUTIVE SUMMARY ....................................................................................................... III 1.0 INTRODUCTION ........................................................................................................ 1 2.0 INFORMATION SOURCES ........................................................................................ 5 3.0 GEOLOGICAL OVERVIEW ........................................................................................ 6 3.1 ROCKS AND LANDFORMS.................................................................................... 6 3.2 RECOGNITION OF ACTIVE FAULTS AND FOLDS ...................................................... 7 4.0 DISTRIBUTION AND CHARACTERISTICS OF ACTIVE FAULTS AND FOLDS IDENTIFIED IN KAIKOURA DISTRICT .................................................................... 13 5.0 IMPLICATIONS FOR HAZARDS.............................................................................. 21 6.0 CONCLUSIONS ....................................................................................................... 25 7.0 ACKNOWLEDGEMENTS ......................................................................................... 26 8.0 REFERENCES ......................................................................................................... 26 FIGURES Figure 1 The tectonic setting of the Kaikoura District. ................................................................................ 2 Figure 2 Illustrations of fault surface rupture offset. .................................................................................... 3 Figure 3 Aerial view looking east along the Hope Fault Zone at Glynn Wye, Hope River valley, Hurunui District. ............................................................................................................................ 4 Figure 4 A view northwest looking along Kaikoura Peninsula towards the Seaward Kaikoura Range. .......................................................................................................................................... 8 Figure 5 Diagrams illustrating styles of active faults and folds. ................................................................ 10 Figure 6 A view north-northwest up the valley of the Waimangarara River where it crosses the Hope Fault Zone at the foot of the Seaward Kaikoura Range. ................................................... 11 Figure 7 A lidar digital elevation model of the area shown in Figure 6, illustrating the precise topographic information revealed by the aerial laser scanning method. ..................................... 12 Figure 8 General distribution of active faults and folds in the Kaikoura District. ....................................... 14 Figure 9 A view northeast along the Clarence Fault, which lies at the southeastern foot of the Inland Kaikoura Range (at left). .................................................................................................. 19 Figure 10 Fault scarp formed on the Chelungpu Fault during the magnitude 7.6 Chi-Chi Earthquake, Taiwan, 1999. ......................................................................................................... 22 Figure 11 Detail of active faults and folds in the Hapuku River to Half Moon Bay areas. ........................... 23 Figure 12 A lidar DEM with hillshade effect showing the area near the junctions of Grange Road (left) and Parsons Road, near the intersection of the Hapuku fault zone and the Hope Fault Zone. ................................................................................................................................. 24 GNS Science Consultancy Report 2014/210 i 2015 TABLES Table 1 Categories and terms used in this report to describe active faults and folds in the Kaikoura District. ........................................................................................................................ 15 Table 2 Summary of evidence and estimated deformation characteristics of active faults and folds recognised in the Kaikoura District (see text for explanation). ........................................... 16 APPENDICES APPENDIX 1: GIS LAYERS .............................................................................................. 30 APPENDIX 2: DETAILED COMMENTARY ON THE MAPPING OF ACTIVE FAULT/FOLD FEATURES IN THE KAIKOURA DISTRICT ........................ 31 APPENDIX FIGURES Figure A2-1a The known, suspected and possible active faults/folds of the northwestern sector of the Kaikoura District plotted on a greyscale version of topographic map NZTopo 250 (Land Information NZ, Crown Copyright reserved). .............................................................................. 55 Figure A2-1b The known, suspected and possible active faults/folds of the northeastern sector of the Kaikoura District plotted on a greyscale version of topographic map NZTopo 250 (Land Information NZ, Crown Copyright reserved). .............................................................................. 56 Figure A2-1c The known, suspected and possible active faults/folds of the southwestern sector of the Kaikoura District plotted on a greyscale version of topographic map NZTopo 250 (Land Information NZ, Crown Copyright reserved). .............................................................................. 57 Figure A2-1d The known, suspected and possible active faults/folds of the eastern sector of the Kaikoura District plotted on a greyscale version of topographic map NZTopo 250 (Land Information NZ, Crown Copyright reserved). .............................................................................. 58 Figure A2-1e The known, suspected and possible active faults/folds of the southern sector of the Kaikoura District plotted on a greyscale version of topographic map NZTopo 250 (Land Information NZ, Crown Copyright reserved). .............................................................................. 59 GNS Science Consultancy Report 2014/210 ii 2015 EXECUTIVE SUMMARY This report presents a general outline of the locations and character of active geological faults and folds in the Kaikoura District. A fault is a fracture within the rock of the Earth’s crust, along which movement has occurred. Commonly, strain builds up in the rock of the Earth’s crust, and is released suddenly by a slip event (rupture) on a fault, causing an earthquake. Folds represent bending or buckling of rock, and commonly form above an underlying fault. A fault or fold is termed ‘active’ where it has moved in the geologically–recent past, in particular where the movement has been sufficiently large to have emerged at the ground surface, forming offset and breakage of the ground (fault) or buckling or tilting of the ground (fold). Old landforms of uniform character, such as river terraces formed during the last ice age which ended about 18,000 years ago, are well suited for revealing the presence of active faults or folds, because they may be old enough to have experienced several rupture events and display large offsets or buckles. In areas of younger landforms, the land surface may be younger than the most recent fault or fold movements, and the presence and location of any active faults or folds may be ‘concealed’ from view. In this way, we can recognise active faults or folds in some places (e.g., where there are ice age river terraces), but elsewhere we may be uncertain whether or not they are present (e.g., on young river floodplains). Regional geological mapping has detected