MFIX (Multiphase Flow with Interphase eXchanges) simulation input files and raw particle output files. The study was published in Breard, E. C., Fullard, L., & Dufek, J. (2024). Rheology of granular mixtures with varying size, density, particle friction, and flow geometry. Physical Review Fluids, 9(5), 054303. Description of files 1. Input particle input file (*.dat) 2. VELOCITY* and FORCES* files exported at 10 Hz The simulation are all done as pressure-controlled shear cells where the x and z axes are periodic boundaries, and the top and bottom boundaries are solid rough plates. The simulations are split in three types: MONODISPERSE, BIDISPERSE and TRIDISPERSE, where particle size (in mm), is indicated in the naming of the directory. The, in each set of simulation, the naming is with the following structure: 20N_0.0001ms, where the first number indicates the confining pressure (20 Newtons) and the second indicate the top plate moving velocity in the x-direction (0.0001 m/s). Note the simulations were run with MFIX-18. The MFIX code that is modified from the core code from the Department of Energy (DOE) is all present. The missing core code can be downloaded from the DOE department https://mfix.netl.doe.gov/.

3D reconstructions and orthophotos of exposures of the 1930 pyroclastic density current on Stromboli. Location 1 is located at UTM W84-33 S_0518638 4295048 and location 2 at UTM W84-33 S_0518956 4294953. The photographs for the models where taken on 28/7/2021 and were converted to the models and orthophotos using structure for motion photogrammetry and the AGISOFT software. The data was collected to aid grain size analysis, by providing a volume change in the outcrop before and after the collection of a physical sample of the material. The data collection was carried by Dr Irene Manzella, Dr Paul Cole and Symeon Makris.

MFIX (Multiphase Flow with Interphase eXchanges) simulation input files and results of simulation of fragmentation-induced fluidization, and laboratory analyses of volcanic pyroclastic density current material. The data consists of: 1) the Fortran90 input files for the MFIX (Multiphase Flow with Interphase eXchanges) TFM simulation runs, 2) the postprocessed MFIX results from our simulations present within Excel sheets 3) laboratory results on the particle shape, size distribution and porosity of the volcanic granular mixtures, presented within Excel sheets. The dataset presented was gathered to investigate the role of compaction, resulting from particle fragmentation, within volcanic granular flows known as pyroclastic density currents. The presented results were obtained from a combination of laboratory analyses and numerical modelling, using Computational Fluid Dynamics. In the laboratory, characterization of the particle size distributions and shape of volcanic grains was undertaken to understand their packing properties. Using the Two-Fluid Model (TFM), an Eulerian-Eulerian method, I was able to simulate the effect of particle breakage on natural scale volcanic mixtures. This model supports a broad range of capabilities for dense multiphase flow. The code was used to investigate the role of particle breakage in pyroclastic density currents, which alters the maximum packing of the granular mixture and ultimately the concentration of the flow during transport. Because the solid phase is immersed in air, the code allowed me to simulate the self-fluidization of the volcanic mixture and the effect on its flowability. These simulations enable me to propose a new process that can play a large role in the occurrence of long runout deadly pyroclastic density currents: Fragmentation-Induced Fluidization. The laboratory work was conducted at the University of Oregon (USA) while the numerical work was completed by running the simulations on the UKRI ARCHER2 HPC and the Talapas Cluster from the University of Oregon (US). The data processing was ongoing from August 2021 to December 2021 (Lab analyses) and February 2022 to August 2022 (HPC work). The MFIX simulation results have been post-processed using ParaView open-source software but can be reproduced by the user using the MFIX custom-changed subroutines and input files contained within the dataset. The data was collected to test the hypothesis that compaction, and subsequent self-fluidization is key to the long-runout of pyroclastic density currents. Specialized audience that work on granular media and volcanic flows. The MFIX code that is modified from the core code from the Department of Energy (DOE) is all present. The missing core code can be downloaded from the DOE department https://mfix.netl.doe.gov/. All the experimental data from lab experiments are presented.

Geochemical analysis of pyroclasts from Aluto, Ethiopia. Data are referenced in Clarke et al., 2019: Fluidal pyroclasts reveal the intensity of peralkaline rhyolite pumice cone eruptions; https://doi.org/10.1038/s41467-019-09947-8.

These data, presented in an excel spreadsheet, where each tab is a different sample (corresponding to the names in the publication), shows the fluid flow volume through time during a permeability measurement, plus the calculation of permeability. These permeability data were used in the publication by Weaver et al. 2023 (https://doi.org/10.1016/j.epsl.2023.118410) The data was collected and analysed at the University of Liverpool and each sample is made of volcanic glass fragments from Hrafntinnuhryggur, Iceland. The geographical location of the samples is here inconsequential for the dataset, the specific obsidian was chosen for its physical properties alone. The experiments were conducted and the data collected and analysed in 2021 and 2022 for publication in 2023. Experiments consisted of placing loose volcanic glass fragments in a crucible and placing the assembly in a high temperature oven (1006 oC) for variable amount of time to sinter them into a coherent material, before cooling and measuring permeability. The permeability measurement was made using the constant head permeability method with synthetic oil as a permeating fluid. This involves the filling of a given height of oil above the sample, creating an overburden that drives fluid flow. Details of the method are provided in detail in Weaver et al., 2023. The data were collected to assess the permeability evolution of fragmental systems undergoing diffusive outgassing, vesiculation and sintering to try to understand the longevity and impact of fragment-filled cracks present in volcanic environments.

Scanning electron microscopy (SEM) and X-ray microtomography of fluidal pyroclasts (X-ray microtomography). Data are referenced in Clarke et al., 2019: Fluidal pyroclasts reveal the intensity of peralkaline rhyolite pumice cone eruptions; https://doi.org/10.1038/s41467-019-09947-8.