VOLCANS: an objective, structured and reproducible method for identifying sets of analogue volcanoes

Abstract

The definition of a suite of analogue volcanoes, or volcanoes that are considered to share enough characteristics as to be considered exchangeable to a certain extent, is becoming a key component of volcanic hazard assessment. This is particularly the case for volcanoes where data are lacking or scarce. Moreover, volcano comparisons have often been based on similarities and differences inferred through expert judgement and not necessarily informed by volcano characteristics from global datasets. These similarities can be based on a range of features, from very simplified (e.g. statrovolcanoes) to very specific (e.g. detailed eruption chronologies), and may be strongly influenced by the personal experience of individuals or teams conducting the analogue analysis. In this work, we present VOLCANS (VOLCano ANalogues Search)-an objective, structured and reproducible method to identify sets of analogue volcanoes from global volcanological databases. Five overarching criteria (tectonic setting, rock geochemistry, volcano morphology, eruption size and eruption style), and a structured combination of them, are used to quantify overall multi-criteria volcano analogy. This innovative method is complementary to expert-derived sets of analogue volcanoes and provides the user with full flexibility to weigh the criteria and identify analogue volcanoes applicable to varied purposes. Some results are illustrated for three volcanoes with diverse features and significant recent and/or ongoing eruptions: Kı̄lauea (USA), Fuego (Guatemala) and Sinabung (Indonesia). The identified analogue volcanoes correspond well with a priori analogue volcanoes derived from expert knowledge. In some cases, single-criterion searches may not be able to isolate a reduced set of analogue volcanoes but any multicriteria search can provide high degrees of granularity in the sets of analogue volcanoes obtained. Data quality and quantity can be important factors, especially for single-criterion searches and volcanoes with very scarce data (e.g. Sinabung). Nevertheless, the method gives stable results overall across multi-criteria searches of analogue volcanoes. Potential uses of VOLCANS range from quantitative volcanic hazard assessment to promoting fundamental understanding of volcanic processes.

Probabilistic Volcanic Hazard Assessment for Pyroclastic Density Currents From Pumice Cone Eruptions at Aluto Volcano, Ethiopia

“…This situation is quite common for many volcanoes around the world (e.g., Loughlin et al, 2015), but obviously introduces epistemic uncertainty into the PVHA results (e.g., Marzocchi et al, 2004). This epistemic uncertainty can be in part reduced using the recently developed VOLCANS methodology to more objectively select the most appropriate volcano analogs based on relatively first-order characteristics of the target volcano (Tierz et al, 2019).…”

Event Trees and Epistemic Uncertainty in Long‐Term Volcanic Hazard Assessment of Rift Volcanoes: The Example of Aluto (Central Ethiopia)

“…10.1029/2020GC009219 Siebert et al, 2010;Tierz et al, 2019). We treat these two events as mutually exclusive and exhaustive events, that is, each eruption may include phreatomagmatic activity or not.…”

“…We then weight the data coming from each different volcano according to its degree of analogy calculated with VOLCANS (see Data Set S5). This allows us to compute the probability of phreatomagmatic and dry magmatic eruptions at Aluto volcano and accounting for the degree of analogy between each available volcano and our target volcano (Tierz et al, 2019). The formula used is the following:…”

“…It should be noted that, given the acute data scarcity across the MER, fine-tuning the analog search may be challenging and the derived sets of analog volcanoes may have very few volcanoes to use. In the end, to estimate a given hazard variable of interest (e.g., distribution of VEI sizes), it might remain a compromise between choosing a one-for-all parameterization (e.g., Mastin et al, 2009), using one or very few analog volcanoes; or an all-for-one parameterization (Tierz et al, 2019), where more general analogs are identified and a larger set of them is used to obtain an average estimate of the hazard variable. Better understanding and optimizing this trade-off between the amount of objectivity and subjectivity that is introduced in a given set of analog volcanoes will likely be a topic for future research.…”

Long-Term Probabilistic Volcanic Hazard Assessment Using Open and Non-open Data: Observations and Current Issues

“…Open data are crucial to help alleviate the widespread issue of data scarcity and, hence, support advancement of PVHA. For instance, open data can be used to borrow useful information from analogue volcanoes (i.e., volcanoes that have enough similar characteristics as to be considered partially exchangeable) and apply it to perform PVHA at a specific (data-scarce) target volcano (e.g., Marzocchi et al, 2004;Bebbington, 2014;Sheldrake, 2014;Ogburn et al, 2016a;Sheldrake et al, 2016;Newhall et al, 2017;Tierz et al, 2019). Some open-access volcanological databases that contain the necessary data to compute PVHA are currently available: Volcanoes of the world, Global Volcanism Program (Siebert et al, 2010; hereinafter GVP) 1 ; WOVOdat 1 http://www.volcano.si.edu (Newhall et al, 2017) 2 ; Large Magnitude Explosive Volcanic Eruptions (Crosweller et al, 2012; hereinafter LaMEVE) 3 and others.…”