Quantifying risk to agriculture from volcanic ashfall: a case study from the Bay of Plenty, New Zealand

摘要: Quantitatively assessing long-term volcanic risk can be challenging due to the many variables associated with hazard and vulnerability. This study presents a structured first-order approach for considering in vulnerability analyses, such as eruption style cyclic fragility, order quantitatively estimate risk. Probabilistic data derived from advection–diffusion–sedimentation tephra fall model TEPHRA2 probabilistic analysis tool BET_VH (Bayesian Event Tree Volcanic Hazards) are combined fragility functions seasonal coefficients agricultural production calculate indices which represent likelihood of damage or loss farm over given time frame. The resulting dataset allows approximations quantitative continuous range ash thickness thresholds, at multiple levels uncertainty, context fluctuating environments (e.g., wind patterns crop phases). We illustrate this through case evaluates incurring 90% dairy fruit farms Bay Plenty region New Zealand (BoP) ashfall Plinian phase large local caldera volcano, Okataina Centre (OVC). Consideration profiles, fluctuations vulnerability, possible OVC styles, different vent locations, distribution thresholds enables multi-dimensional that aims reflect natural complexity interdependencies A uncertainty matrix is introduced conceptual scheme help guide evaluation communication results analyses by showing how types yield “maximum”, “average”, “minimum” estimates Results indicate BoP higher experiencing than farms, east typically north OVC. Forecasts based on annual maximum show regional average 2.3% probability (greater 1 50 likelihood) basaltic rhyolitic anywhere within period 100 years. Seasonal-level revealed losses fluctuates year harvest season, highest experienced during peak season (15 October–14 April) when high westerly winds dominate BoP.