Grain size analysis of volcanic ash: Methods intercomparison and best practices
Organisers:
- Alexa Van Eaton (U.S. Geological Survey)
- Samantha Engwell (British Geological Survey)
- Julia Eychenne (Université Clermont Auvergne)
- David Damby (U.S. Geological Survey)
- Thomas Jones (Lancaster University, UK)
- Johanne Schmith (USGS HVO)
- Hannah Buckland (Swansea University)
The grain size of volcanic deposits is a key parameter for interpreting eruptive processes. Although sieving has long provided the benchmark for lapilli and ash-sized particles, the last few decades have seen a proliferation of new methods, including laser diffraction and dynamic image analysis for ash. With the growing availability of novel instruments, how can we ensure comparable results across diverse eruption styles, legacy datasets, and laboratory users? This half-day workshop will present the results of an inter-laboratory comparison of grain size methods through the IAVCEI Commission on Tephra Hazard Modeling, followed by round-table discussions with the workshop’s participants. We will discuss best practices in testing and applying new approaches with the goals of: (1) defining existing state-of-the-art protocols, (2) identifying strategies to reduce uncertainty, and (3) converging on future recommendations. Early-career and senior scientists are encouraged to attend, regardless of prior participation in the inter-laboratory comparison exercise.