The utility of earth science information in post-earthquake land-use decision-making: the 2010–2011 Canterbury earthquake sequence in Aotearoa New Zealand

Abstract. Earth science information (data, knowledge, advice) can enhance the evidence base for land-use decision-making. The utility of this information depends on factors such as the context and objectives of land-use decisions, the timeliness and efficiency with which earth science information is delivered, and the strength, relevance, uncertainties and risks assigned to earth science information relative to other inputs. We investigate land-use decision-making practices in Christchurch, New Zealand and the surrounding region in response to mass movement (e.g., rockfall, cliff collapses) and ground surface fault rupture hazards incurred during the 2010-2011 Canterbury earthquake sequence (CES). Rockfall fatality risk models combining hazard, exposure and vulnerability data were co-produced by earth scientists and decision-makers and formed primary evidence for risk-based land-use decision-making with adaptive capacity. A public decision appeal process enabled consideration of additional earth science information, primarily via stakeholder requests. For fault rupture hazards, pre-disaster geotechnical guidelines and collaboration networks enhanced the ability of earth scientists to rapidly acquire relevant observational data to meet the demands of decision-makers. Expeditious decision-making granted permissive consent for rebuilding in the fault rupture zone based on preliminary scientific advice that was subsequently supported by more comprehensive geological investigations. Rapidly fluctuating and diverse demands for post-disaster earth science information may be best met through prior establishment of (i) land-use policies and technical guidelines tailored for a variety of diverse disaster scenarios, (ii) hazard and risk analyses in land-use plans, including acquisition of geospatial and other earth science data, and (iii) co-ordinated science networks that may comprise sub-groups with diverse goals, operational perspectives and protocols, which allow the many facets of science information acquisition and delivery to be successfully addressed. Despite the collective knowledge shared here, some recent land use practices in New Zealand continue to prioritize other (e.g., socioeconomic) factors above earth science information, even in areas of extreme disaster risk.