Spatial probabilities of eruption scenarios : a case study of the Auckland Volcanic Field, New Zealand

• Main Author: Ang, Pei Shan
• Other Authors: Susanna Jenkins
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Science::Geology::Volcanoes and earthquakes
• Online Access: http://hdl.handle.net/10356/77272
• Institution: Nanyang Technological University

Monogenetic volcanic fields, where the location of the next eruptive vent is not known, pose unique challenges to hazard managers. This is further compounded by the lack of knowledge on possible eruption styles at a location. Previous key forecasting methods to improve hazard management include probabilistic and scenario-based approaches. However, probabilistic approaches do not usually involve forecasts of future eruption style and scenario-based approaches tend to focus only on one location per scenario. Our study introduces the novel combined probabilistic-scenario approach, where probabilities will be used to determine locations where scenarios with varying eruptive styles are most likely to occur. This is applied to the Auckland Volcanic Field (AVF), which houses New Zealand’s largest city. Scenarios for the AVF, each with an intended location, was developed by the research team at Determining Volcanic Risk in Auckland (DEVORA). The primary aim of our study is to show that some scenarios are more likely to occur in certain areas due to various environmental conditions, which was beyond the scope of past research. Environmental conditions and past AVF eruption data were used to construct probability formulas to determine the spatial probability of occurrence for scenarios according to their eruption style. The resultant spatial probability maps quantified the spatial likelihood of occurrence per eruption scenario throughout the AVF. Sensitivity analysis on the spatial probability maps has also shown that the degree of sensitivity for calculated probability values is generally related to the particular environmental conditions of the location and that no factor appears to be equally influential across the AVF. Relative spatial probability maps were produced as well, allowing for a comparison to be made across scenarios at each location. The results indicate that there are other areas, apart from the intended location, where an eruption scenario may occur at high probability. Therefore, possible future work includes the shifting of eruption scenarios to areas identified to be of higher probability to obtain impact assessments for a range of eruption consequences. It is envisioned that the results from this study will be used in the improvement of management decisions for volcanic risk in the AVF. We believe that our methodology can be applicable on a wider scale as well, given further work on eruption styles and controlling factors for global volcanoes.