Explosive eruptions rarely comprise one discrete event, but rather a succession of phases. Throughout the eruption these phases may generate a range of volcanic hazards, each with varying temporal and spatial scales. Geologic and socio-volcanic studies highlight the increased risk associated with a long duration capricious eruption. Multiple phases within an eruption disperse ash into different wind conditions, affecting a greater number of people than a discrete eruptive event. Some communities may have recurrent ash falls over many years. Mitigation of the repeated disruption to lifeline utilities, business continuity and infrastructure is likely to be complicated by the long duration. We are working to develop and implement a probabilistic volcanic risk assessment framework for the Rotorua area of New Zealand, with particular recognition of the expected multi-phase nature of future eruption scenarios. The probabilistic approach allows uncertainties, intrinsic to any volcanic system, to be incorporated. The framework uses an event tree structure within modules; each signifying major components and dynamics of the hazard and risk. Each node of the event tree allows increasingly more specific outcomes to be considered, leading to a model fully cognisant of the probable risk. The initial hazard module includes probability distributions describing total eruption duration, time separating eruption onset and peak, phase duration, time separating phases and phase magnitude. This information is gained from studies of the geological record, analogous historic eruptions and knowledge of physical volcanic processes. This module forms a strong base for future numerical hazard simulation and risk calculation. Further work will combine additional modules to form a scientifically based probabilistic model to analyse the hazard and resultant risk from future explosive multi-phase volcanic eruptions in the Rotorua area. The model will be generic and applicable to other urban areas at risk of volcanic eruptions.
|Number of pages||1|
|Publication status||Published - 2006|
|Event||Cities on Volcanoes (4th : 2006) - Quito, Ecuador|
Duration: 23 Jan 2006 → 27 Jan 2006
|Conference||Cities on Volcanoes (4th : 2006)|
|Period||23/01/06 → 27/01/06|