Assessment of liquefaction hazards in the Queenstown Lakes, Central Otago, Clutha and Waitaki districts of the Otago Region DJA Barrell GNS Science Consultancy Report 2018/67 June 2019 DISCLAIMER This report has been prepared by the Institute of Geological and Nuclear Sciences Limited (GNS Science) exclusively for and under contract to Otago Regional Council. 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 Otago Regional Council and shall not be liable to any person other than Otago Regional Council, on any ground, for any loss, damage or expense arising from such use or reliance. Use of Data: Date that GNS Science can use associated data: May 2019 BIBLIOGRAPHIC REFERENCE Barrell DJA. 2019. Assessment of liquefaction hazards in the Queenstown Lakes, Central Otago, Clutha and Waitaki districts of the Otago Region. Lower Hutt (NZ): GNS Science. 99 p. Consultancy Report 2018/67. Project Number 440W1514 2019 CONTENTS EXECUTIVE SUMMARY ....................................................................................................... V 1.0 INTRODUCTION ........................................................................................................1 1.1 Overview .........................................................................................................1 1.2 Scope of Work ................................................................................................. 1 1.3 Liquefaction Hazard Assessment Methodology ............................................... 3 1.4 Data Sources and Mapping Methods ............................................................... 4 1.5 Report Layout ..................................................................................................4 2.0 BACKGROUND INFORMATION .............................................................................. 10 2.1 Geological Setting ......................................................................................... 10 2.2 Seismicity ...................................................................................................... 11 2.3 The Nature and Occurrence of Liquefaction and Lateral Spreading ............... 12 3.0 ASSESSMENT OF LIQUEFACTION HAZARDS ...................................................... 14 3.1 Liquefaction-Susceptibility Domains .............................................................. 14 3.2 What the Liquefaction-Susceptibility Domains Mean: ..................................... 14 3.2.1 Domain A ......................................................................................................... 14 3.2.2 Domains B, B1 and C ...................................................................................... 15 3.3 Accuracy and Limitations of the Liquefaction-Susceptibility Mapping ............. 16 3.4 Description of the Areas Mapped ................................................................... 16 3.4.1 General Description ......................................................................................... 16 3.4.2 Queenstown Lakes District .............................................................................. 17 3.4.3 Central Otago District ...................................................................................... 19 3.4.4 Clutha District .................................................................................................. 19 3.4.5 Waitaki District ................................................................................................. 22 4.0 DISCUSSION............................................................................................................ 24 4.1 Comparison with Previous Work .................................................................... 24 4.2 Overall Assessment ....................................................................................... 24 5.0 CONCLUSIONS ....................................................................................................... 27 6.0 ACKNOWLEDGMENTS ........................................................................................... 28 7.0 REFERENCES ......................................................................................................... 28 FIGURES Figure 1.1 Location of the Otago region and its constituent territorial authority areas (district or city councils), along with Otago’s distribution of Quaternary-age sediments. ..................................... 2 Figure 1.2 Background information sources for the Queenstown Lakes District. .......................................... 6 Figure 1.3 Background information sources for the Central Otago District. ................................................... 7 Figure 1.4 Background information sources for the Clutha District. ............................................................... 8 Figure 1.5 Background information sources for the Waitaki District. ............................................................. 9 GNS Science Consultancy Report 2018/67 i 2019 Figure 2.1 Photos illustrating some effects of liquefaction and lateral spreading. ....................................... 13 Figure 3.1 Overview map of liquefaction susceptibility domains for the Queenstown Lakes District. .......... 18 Figure 3.2 Overview map of liquefaction-susceptibility domains for the Central Otago District. .................. 20 Figure 3.3 Overview map of liquefaction-susceptibility domains for the Clutha District. .............................. 21 Figure 3.4 Overview map of liquefaction-susceptibility domains for the Waitaki District. ............................. 23 TABLES Table 4.1 Evaluation of the relative extents of liquefaction-susceptibility domains in the districts of Otago (excluding Dunedin). .................................................................................................................. 24 APPENDICES APPENDIX 1 EXPLANATION OF TERMS .............................................................. 33 APPENDIX 2 PREVIOUS REGIONAL-SCALE LIQUEFACTION HAZARD MAP .... 36 APPENDIX 3 DESCRIPTION OF THE MAPPED EXTENTS OF LIQUEFACTION- SUSCEPTIBILITY DOMAINS B AND C ............................................. 37 A3.1 Queenstown Lakes District ............................................................................ 37 A3.1.1 Upper Wakatipu (Figure A3.2) ......................................................................... 37 A3.1.2 Lake Wakatipu perimeter ................................................................................ 40 A3.1.3 Queenstown and Wakatipu Basin (Figures A3.3–A3.5) .................................. 41 A3.1.4 Kingston (Figure A3.6) .................................................................................... 46 A3.1.5 Moke Lake ....................................................................................................... 48 A3.1.6 Shotover valley ................................................................................................ 48 A3.1.7 Lake Wanaka perimeter (Figures A3.7–A3.8) ................................................. 48 A3.1.8 Wanaka (Figure A3.7) ..................................................................................... 48 A3.1.9 Cardrona valley ............................................................................................... 49 A3.1.10 Matukituki valley ............................................................................................. 49 A3.1.11 Makarora area (Figure A3.9) .......................................................................... 52 A3.1.12 Lake Hawea area ........................................................................................... 52 A3.1.13 Hawea River and upper Clutha River area .................................................... 52 A3.2 Central Otago District .................................................................................... 54 A3.2.1 Upper Clutha valley ......................................................................................... 54 A3.2.2 Alexandra area and Manuherikia valley (Figures A3.10, A3.11) ..................... 54 A3.2.3 Ida Valley and Poolburn valley ........................................................................ 57 A3.2.4 Upper Pool Burn – Manor Burn ....................................................................... 57 A3.2.5 Maniototo basin (Figures A3.12, A3.13) .......................................................... 57 A3.2.6 Clutha valley and adjacent areas .................................................................... 57 A3.3 Clutha District ................................................................................................ 60 A3.3.1 Beaumont, Lawrence and Waitahuna areas (Figures A3.14–A3.16).............. 60 A3.3.2 Heriot and Tapanui areas (Figures A3.17, A3.18) .......................................... 64 A3.3.3 Pomahaka headwaters .................................................................................... 64 A3.3.4 Arthurton to Balclutha tableland (Figure A3.19) .............................................. 64 ii GNS Science Consultancy Report 2018/67 2019 A3.3.5 The Catlins (Figures A3.20, A3.21) ................................................................. 68 A3.3.6 Clutha valley and Balclutha (Figure A3.22) ..................................................... 68 A3.3.7 Inch Clutha area (Figures A3.23–A3.25) ......................................................... 68 A3.3.8 Otago coast — Clutha River to Taieri