Skip to content

Energy line approaches in a level set framework for probabilistic modelling of volcanic surges

Stuart Mead1, James Williams2, Josh Hayes3

  • Affiliations:  1Volcanic Risk Solutions, Massey University; 2University of Canterbury, New Zealand; 3GNS Science, New Zealand 

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 58

  • Programme No: 6.3.17

  • Theme 6 > Session 3

Abstract

Energy line approaches are often used to delineate pyroclastic surge extent, favoured in PVHA for their computational speed and simple input parameters. However, outputs are limited to inundation extent, do not account for flow channelisation or cross-axis flow, and input parameters that can be difficult to relate to physical characteristics of the eruption. The difficulty is to account for these factors while not compromising on computational time. Here, we have reformulated energy-based approaches in a level-set framework. This formulation iteratively defines the frontal position of the surge using a propagation function, which enables new advancements to energy line approaches such as channelisation, dependence on mass discharge rate and settling velocity, flow redirection (e.g. 'tree-branching') and potentially extraction of hazard intensity functions. The framework utilises graphics processing units, meaning the computational cost of this reformulation is negligible, and allows for large sample spaces necessary in PVHA. The new approach is demonstrated in an application to the Auckland volcanic field, an application with varying vent locations and eruption sizes. This application took 10 hours to complete for 5,000 simulations, and supported the extraction of surge hazard in terms of extent and intensity. We show the results of this application, validations against New Zealand surges and demonstrate some potential extensions using this framework to account for different energy approaches (e.g. energy conoid), flow redirection, and discuss the suitability of extracting a hazard intensity measure from the level set framework.