Project Number: 5-MB97C.02 Waitohi Picton Ferry Precinct Re-development 15 October 2020 CONFIDENTIAL Slope, Seismic and Tsunami Hazards Assessment Contact Details Bill Leask WSP L9 Majestic Centre 100 Willis Street Wellington 6011 +64 4 471 7000 +64 27 240 2274 [email protected] Document Details: Date: 15 October 2020 Reference: GER 2020/16 Status: Issue 3 Prepared by Bill Leask Helen Hendrickson Reviewed by Campbell Keepa Approved for release by Matthew Taylor ©WSP New Zealand Limited 2020 i Document History and Status Revision Date Author Reviewed by Approved by Status Issue 1 29 May W Leask C Keepa M Taylor 2020 H Hendrickson Issue 2 2 Sep 2020 W Leask C Keepa M Taylor H Hendrickson Issue 3 15 Oct 2020 W Leask C Keepa M Taylor H Hendrickson Revision Details Revision Details Issue 2 Revised following reviews by Mitchell Daysh Issue 3 Revised following Phase 2 analysis ©WSP New Zealand Limited 2020 ii Contents Disclaimers and Limitations .................................................................................................................................................................................. 1 1 Introduction ........................................................................................................................................................................................................ 2 1.1 Purpose and scope ......................................................................................................................................................................... 2 1.2 Referenced documents ............................................................................................................................................................. 2 2 The Site .................................................................................................................................................................................................................... 2 2.1 Location .................................................................................................................................................................................................... 2 2.2 Project area ........................................................................................................................................................................................... 3 3 Geological Setting .......................................................................................................................................................................................... 3 3.1 Geomorphology and stratigraphy ..................................................................................................................................... 3 3.2 Groundwater ........................................................................................................................................................................................ 4 3.3 Faulting ..................................................................................................................................................................................................... 4 4 Slope Hazards ................................................................................................................................................................................................... 6 4.1 Slopes adjacent to Port Marlborough ........................................................................................................................... 6 4.2 Slope hazard ....................................................................................................................................................................................... 6 5 Seismic Hazards.............................................................................................................................................................................................. 6 5.1 Previous earthquakes .................................................................................................................................................................. 6 5.2 Surface fault rupture hazard ................................................................................................................................................. 8 5.3 Earthquake ground shaking hazard............................................................................................................................... 8 5.4 Tectonic land movement ....................................................................................................................................................... 12 6 Liquefaction Hazard ................................................................................................................................................................................... 12 6.1 Liquefaction in previous earthquakes .......................................................................................................................... 12 6.2 Liquefaction and Soil Cyclic Softening ........................................................................................................................ 12 6.3 Free Field Settlements .............................................................................................................................................................. 14 6.4 Lateral Spreading Hazard ....................................................................................................................................................... 14 7 Tsunami and Seiche Hazard ...............................................................................................................................................................16 7.1 Tsunami and Seiche ....................................................................................................................................................................16 7.2 Wave heights and inundation areas ..............................................................................................................................16 7.3 Tsunami sources and arrival times .................................................................................................................................. 17 8 Summary of Natural Hazards .............................................................................................................................................................18 9 Managing Risk from Natural Hazards .........................................................................................................................................19 9.1 Evaluating risk from natural hazards ............................................................................................................................19 9.2 Climate change ............................................................................................................................................................................. 20 ©WSP New Zealand Limited 2020 iii 9.3 Risk management options .................................................................................................................................................. 20 10 References ........................................................................................................................................................................................................ 20 List of Figures Figure 1: Location of Port Marlborough, Picton. Map extracted from https://www.topomap.co.nz, accessed 1 May 2020. Grid lines are spaced at 10 km. ................................................................................................................. 2 Figure 2. Aerial photograph map of Picton with the project area outlined in yellow (Source: https://maps.marlborough.govt.nz/) .............................................................................................................................................................. 3 Figure 3. Geological map of the Picton area, extracted from the 1:250 000 QMAP Wellington (Begg & Johnston 2000). The Q1n area in pale yellow is the approximate area of reclamation. ........... 4 Figure 4. Active faults in the Marlborough – Cook Strait – Wellington region (from Wallace et al. 2012). ......................................................................................................................................................................................................................................... 5 Figure 5: Kaikōura Earthquake Damage Observations ................................................................................................................ 8 Figure 6: Comparison of 5% damped response spectra from PSHA and NZS 1170.5. .................................... 10 Figure 7: Amplification between effective bedrock at 90 m depth to the surface for 25, 50 and 2500 year return period events........................................................................................................................................................................ 11 Figure 8: Typical Stability Section (Behind Wharves). ................................................................................................................... 15 Figure 9: Typical Stability Analysis (Carpark and Terminal Building) .............................................................................. 15 Figure 10: MDC Tsunami evacuation zones in Picton (from Heron et al. 2015). ....................................................