Combined earthquake hazard map City

Slope failure Key to slope failure susceptibility zones Very high High Moderate Low Very low Grenada Village

Johnsonville Newlands


Liquefaction potential Key to liquefaction potential zones High Moderate Low Variable No Ngaio




Groundshaking Key to ground shaking hazard High Moderate Low Variable No Kelburn Roseneath KEY Mt Victoria Hazard index Low Mt Cook Mitchelltown Brooklyn Medium Newtown Kilbirnie Miramar

Rongotai Tsunami and fault lines Berhampore High Key to tsunami inundation and faultline Land that will be inundated Roads Major fault Land outside study area

Island Bay Owhiro Bay


Major fault

Background statement Earthquake Hazard Mitigation Measures In recognition of the earthquake hazard in the Region, the Greater Wellington Regional Council has carried out studies on ground surface rupture from active faulting, ground shaking, liquefaction potential and associated ground damage, slope failure and tsunami inundation (). Single factor hazard maps have been produced by Greater Wellington for each of these earthquake hazards. Hazard Effect on ground Effect on Mitigation options: Mitigation options: planned This map sheet is part of a series of four map sheets showing the combined earthquake hazard for the main urban areas in the western part of the Wellington facilities existing facilities facilities Region. The map series is one of Greater Wellington’s natural hazard education and awareness initiatives. Fault Ground disturbances vertically and Upheaval, tearing apart, 1. Verify. 1. Verify. The combined earthquake hazard map is a generalised map of earthquake hazard refl ecting possible effects on a typical range of facilities (buildings, roads, horizontally over a zone depends on movement of foundations, 2. Assess impact. 2. Assess impact. services, etc). The methodology has involved broad assessments of many factors which determine the effects of earthquakes. movement depth to rock below surface. Cracks in severe damage to structures 3. Options: 3. Options: This map series was prepared for Greater Wellington by Ian R Brown Associates Ltd in association with Kingston Morrison Ltd and Victoria University of land surface. which cross the fault. a) strengthen to survive a) construct facilities elsewhere Wellington. b) move facilities from fault zone b) incorporate special strengthening c) limit damage by providing weak links c) provide weak links or special isolation to limit Warning or isolation damage The hazard assessment methodologies developed for each of the earthquake hazard components and the methodology used to combine and present the hazard information impose certain qualifi cations and limitations on the use of the information. Details on the qualifi cations and limitations, and assessment Violent horizontal and vertical motions Cracking, fracture, collapse 1. Verify. 1. Verify. Ground methodologies of the component earthquake hazard studies are available from Greater Wellington. The methodology used to combine the various for up to one minute duration. of buildings. Breaks in shaking 2. Assess impact. 2. Assess impact. earthquake hazards are described in the Greater Wellington Report on Mapping Methodology and Risk Mitigation Measures WRC/RP-T-96/22. underground services. 3. Options: 3. Options: Deformation of surface a) strengthen or base isolate a) comply with current codes for design and The information provided on these maps cannot be substituted for a site specifi c investigation. The site specifi c potential for and consequent damage from infrastructure. active faulting, amplifi ed ground shaking, liquefaction, slope failure, and tsunami inundation should be assessed by qualifi ed and experienced practitioners. b) secure/improve vulnerable parts construction c) limit damage by providing weak links b) incorporate strength and resilience Bibliographic reference or isolation. c) secure vulnerable parts and contents Greater Wellington Regional Council (1996). Sheet 1 Wellington (1st ed.) Combined Earthquake Hazard Map 1:30000, Pub . No. WRC/RP-T-96/13 Greater Liquefaction Shaking causes some soils to behave Sinking and tilting of structures 1. Verify. 1. Verify. Wellington Regional Council, Wellington, . like liquid, causing loss of support supported on liquefi ed material. 2. Assess impact. 2. Assess impact. to structures above. Such soils may Severe damage to underground 3. Options: 3. Options: Notes on earthquake hazard mitigation measures be up to 10m below ground surface. services. Flotation of empty a) install piles a) compact ground at site 1. Check that the broad indication of hazard from the maps is correct for a particular site. (In many case, this could prove cost-effective towards Lateral movement of large soil masses, underground tanks and mitigation.) especially adjacent to rivers. Variable chambers. b) install gravel drains b) install piles and gravel drains subsidence of ground surface. c) drain liquefi able layers c) drain liquefi able layers 2. Obtain professional advice on implications and available countermeasures. d) prepare for quick reinstatement 3. Mitigation options shown are in brief general terms. Professional advice will be needed to account for particular circumstances at the site. Slope failure A signifi cant soil masses moves bodily Ranges from deformation of 1. Verify. 1. Verify. Single component hazard maps down the slope, from few hundred foundations and structural 2. Assess impact. 2. Assess impact. These combine to produce the Combined Earthquake Hazard Maps. Maps of the single components (ground shaking, liquefaction and earthquake induced millimetres to many metres. Landslides failures to total destruction 3 Options: 3. Options: slope failure) are available from the Hazard Analyst at Greater Wellington. occur at many different locations. of site and all buildings and a) stabilise slope – retaining walls a) fi nd a better site infrastructure above and below Copyright: Wellington Regional Council. The topographic information used in this map has been reproduced under licence from b) stabilise slope – ground anchors b) stabilise slope retaining walls ground. Land Information New Zealand (LINZ). Crown Copyright Reserved. c) improve drainage, reduce erosion c) stabilise slope – ground anchors d) improve drainage, reduce erosion Tsunami Land fl ooded. Scouring action erodes Flooding of basements. 1. Verify. 1. Verify. soil dramatically Undermining/destruction of 2. Assess impact. 2. Assess impact. surface infrastructure. Exposure/ 3. Options: 3. Options: damage to underground a) construct protective sea walls a) fi nd a better site services. Undermining of foundations. Bodily movement b) shift critical facilities to higher level b) construct protective sea walls of some structures, equipment, c) design special foundations / dikes vehicles etc. d) put critical facilities at high level