Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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Author: search.filters.author.Bebbington MSSubject: search.filters.subject.Emergency management

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    Modelling spatial population exposure and evacuation clearance time for the Auckland Volcanic Field, New Zealand
    (Elsevier BV, 2021-08) Wild AJ; Bebbington MS; Lindsay JM; Charlton DH
    Auckland, New Zealand's largest city (population of ~1.6 million), is situated atop the monogenetic Auckland Volcanic Field (AVF). As in many places faced with volcanic activity, evacuation is seen as the best risk mitigation strategy for preserving lives in the event of volcanic unrest and/or an eruption. However, planning for an evacuation can be challenging. In particular, the uncertainty in vent location resulting from the monogenetic nature of the field makes identifying neighbourhoods to be evacuated impractical until well into the pre-eruption unrest period. This study uses spatial analysis methods to assess exposure for both population and private transport ownership as well as to identify those areas requiring public transport support for an evacuation. These data were overlaid on a range of possible vent locations across the AVF using a 500 × 500 m grid. At each possible vent location, a 5 km evacuation zone is modelled, following the official contingency plan for evacuation in a future AVF event. In order to simulate vent location uncertainty leading up to a future eruption, a range of buffer distances were applied around the modelled vent locations. The exposure data derived were then used to model evacuation clearance time, which considered four phases: 1) the time taken to decide to call an evacuation; 2) the public notification time; 3) the evacuee's time to prepare; and 4) evacuee's travel time to beyond the evacuation zone. The length of time involved in phases 1 to 3 are all independent of the vent location; our analysis found these phases could be completed within 36 h, with over 80% confidence. Travel times to beyond the evacuation zone were modelled using the exposure analysis for population and private transport ownership combined with road network data and vehicle carrying capacity. This revealed travel times for this phase ranging from less than 1 up to 11 h, depending on traffic congestion, when considering no vent uncertainty. By combining the times modelled for all four phases, we found that when there is high certainty in the vent location, the median total evacuation clearance time with no congestion is approximately 37 h. However, include a 10 km vent uncertainty buffer into the model, the evacuation clearance time can increase to between 38 and 55 h, dependent on traffic congestion. A vent in the densely populated inner Auckland and CBD area would result in the greatest population required to evacuate, and also the greatest need for public transport support given the low vehicle ownership in this area. Our results can be used to inform emergency management decision making, and the model can be adapted for other regions as well as for other hazards.
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    A modular framework for the development of multi-hazard, multi-phase volcanic eruption scenario suites
    (Elsevier BV, 2022-07) Weir AM; Mead S; Bebbington MS; Wilson TM; Beaven S; Gordon T; Campbell-Smart C
    Understanding future volcanic eruptions and their potential impact is a critical component of disaster risk reduction, and necessitates the production of salient, robust hazard information for decision-makers and end-users. Volcanic eruptions are inherently multi-phase, multi-hazard events, and the uncertainty and complexity surrounding potential future hazard behaviour is exceedingly hard to communicate to decision-makers. Volcanic eruption scenarios are recognised to be an effective knowledge-sharing mechanism between scientists and practitioners, and recent hybrid scenario suites partially address the limitations surrounding the traditional deterministic scenario approach. Despite advances in scenario suite development, there is still a gap in the international knowledge base concerning the synthesis of multi-phase, multi-hazard volcano science and end-user needs. In this study we present a new modular framework for the development of complex, long-duration, multi-phase, multi-hazard volcanic eruption scenario suites. The framework was developed in collaboration with volcanic risk management agencies and researchers in Aotearoa-New Zealand, and is applied to Taranaki Mounga volcano, an area of high volcanic risk. This collaborative process aimed to meet end-user requirements, as well as the need for scientific rigour. This new scenario framework development process could be applied at other volcanic settings to produce robust, credible and relevant scenario suites that are demonstrative of the complex, varying-duration and multi-hazard nature of volcanic eruptions. In addressing this gap, the value of volcanic scenario development is enhanced by advancing multi-hazard assessment capabilities and cross-sector collaboration between scientists and practitioners for disaster risk reduction planning.