PARTIcle Shape ANalyzer PARTISAN – an open source tool for multi-standard two-dimensional particle morphometry analysis

Volcanic particles are commonly characterized using 2D morphometric analysis. Results of analysis are used to compare particles from different events or phases, and to infer clast-generating mechanisms, eruptive styles and the aerodynamic behavior of particles. Such particle-shape analyses can be made from images of particle silhouettes or cross-sectional slices. A number of different morphometric systems have been used to date, with each using its own nomenclature and mathematical definitions of shape-describing parameters. Some of the parameters can only be obtained using specific commercial software.With the PARTIcle Shape ANalyzer PARTISAN we present a freeware tool which parameterizes 2D shapes and provides a suite of shape parameters, following the different standards of the five most commonly used 2D morphometric systems. PARTISAN enables the user to study and archive the results of particle-shape analysis in a format compatible with various published routines, thus increasing the potential for linking new work with results of work previously published by other groups. It will also allow cross-comparison of results obtained by different morphological routines. We see PARTISAN as a "Rosetta Stone" for volcanological particle morphometry, and it opens the way for development of widely agreed treatment of particle shapes in 2D.