Abstract
Abstract Forecasting future destructive eruptions from re‐awakening volcanoes remains a challenge, mainly due to a lack of previous event data. This sparks a search for similar volcanoes to provide additional information, especially those with better compiled and understood event records. However, we show that some of the most obviously geologically comparable volcanoes have differing statistical occurrence patterns. Using such matches produces large forecasting uncertainties. We created a statistical tool to identify and test the compatibility of potential analogue volcanoes based on repose‐time characteristics from world‐wide datasets. Selecting analogue volcanoes with compatible behavior for factors being forecast, such as repose time, significantly reduces forecasting uncertainties. Applying this tool to Tongariro volcano (NZ), there is a 5% probability for a Volcanic Explosivity Index (VEI) ≥ 3 explosive eruption in the next 50 years. Using pre‐historic geological records of a smaller available set of analogs, we forecast a 1% probability of a VEI ≥ 4 eruption in the next 50 years.
Plain Language Summary Probabilistic forecasts of future destructive eruptions from re‐awakening volcanoes can inform decision‐making to help mitigate volcanic risk. However, a lack of data describing previous events at many volcanoes hinders robust forecasts. Often, the only available forecasts are those based on expert judgment and knowledge of other similar but better known volcanoes. We show that eruption forecasting based only on comparisons of geological criteria produces large uncertainties. We created an alternative statistical tool to identify and test the compatibility of potentially analogous volcanoes based on the time between successive eruptions from individual volcanoes worldwide. Selecting volcanoes with analogous statistical features in terms of the time breaks between successive eruptions significantly reduces the uncertainty of eruption forecasts. We applied this tool to forecasting explosive eruptions at NZ Tongariro volcano using two sets of analogs we identified and found a 5% probability of a Volcanic Explosivity Index (VEI) ≥ 3 eruption and 1% probability of a VEI ≥ 4 eruption in the next 50 years.
Key Points We create a statistical tool to identify potential analogue volcanoes based on repose‐time characteristics from world‐wide datasets Analogs selected by this tool significantly reduce forecasting uncertainties compared to using analogs selected by geological similarity We apply this tool to forecasting explosive eruptions at Tongariro volcano in New Zealand