Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item Short-Term Eruption Forecasting for Crisis Decision-Support in the Auckland Volcanic Field, New Zealand(Frontiers Media S.A., 2022-05-24) Wild AJ; Bebbington MS; Lindsay JM; Wright HMAuckland, a city of 1.6 million people, is situated atop the active monogenetic Auckland Volcanic Field (AVF). Thus, short-term eruption forecasting is critical to support crisis management in a future event, especially to inform decisions such as calling evacuations. Here we present an updated BET_EF for the AVF incorporating new data and the results of an expert-opinion workshop, and test the performance of the resulting BETEF_AVF on eight hypothetical eruption scenarios with pre-eruptive sequences. We carry out a sensitivity analysis into the selection of prior distributions for key model parameters to explore the utility of using BET_EF outputs as a potential input for evacuation decision making in areas of distributed volcanism such as the AVF. BETEF_AVF performed well based on the synthetic unrest dataset for assessing the probability of eruption, with the vent outbreaks eventuating within the zone of high spatial likelihood. Our analysis found that the selection of different spatial prior model inputs affects the estimated vent location due to the weighting between prior models and monitoring inputs within the BET_EF, which as unrest escalates may not be appropriate for distributed volcanic fields. This issue is compounded when the outputs are combined with cost-benefit analysis to inform evacuation decisions, leading to areas well beyond those with observed precursory activity being included in evacuation zones. We find that several default settings used in past work for the application of BET_EF and CBA to inform evacuation decision-support are not suitable for distributed volcanism; in particular, the default 50-50 weighting between priors and monitoring inputs for assessing spatial vent location does not produce useful results. We conclude by suggesting future cost-benefit analysis applications in volcanic fields appropriately consider the spatial and temporal variability and uncertainty characteristic of such systems.Item Intra-Eruption Forecasting Using Analogue Volcano and Eruption Sets(John Wiley and Sons, Inc on behalf of the American Geophysical Union, 2022-06-23) Bebbington MS; Jenkins SFForecasting the likely style and chronology of activity within an eruption is a complex issue that has received far less attention than forecasting the onset and/or the magnitude. By developing a global data set of coded phases (discrete styles of activity within previous eruptions), we can model the resulting data using a semi-Markov chain. Given enough data, we were able to examine the question of whether analogue-based strategies for subsetting the data can improve forecasting performance of phase chronology and style within ongoing eruptions. This work required inclusion of a “null analogue” element to ensure no surprises, that is, phase transitions or durations that were not in the data set and hence cannot be predicted. We have significantly expanded, and made available, our curated data set on eruption phases, which now contains 2670 eruptions (6871 phases), of which 56% are multi-phase. This increases the data set by 283% and includes 95% of Holocene eruptions with text descriptions. We find that, with the notable exception of shields, limiting the analogue set on the basis of volcano morphology and/or composition is not significantly more informative than using the entire data set. Dynamically adjusting the data limits by eliminating eruptions without the observed phase as the eruption progresses provided little benefit, although subsetting on the basis of VEI may have some utility. At the individual volcano level, non-analogue models can outperform the entire data set, if the target volcano has relatively unique behavior and/or a large enough record of phased eruptions.