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The 2002 effusive flank eruption at Stromboli volcano started on December 28, after several months of strong explosive activity at the summit craters. On December 30, the seismic network recorded two large flank failures and associated tsunami waves. This is the first time that a flank collapse and tsunami, and their associated phenomena, have been recorded by a multi‐disciplinary monitoring system. Volcanological and geophysical monitoring, as well as thermal surveys performed immediately before and after the failure, allowed us to define and interpret the sequence of events. The still on‐going eruption has provided, for the first time, the opportunity to look into the dynamics of Stromboli's effusive eruptions, flank failure and landslide formation, and their potential hazard.

X-ray microcomputed tomography (X-ray μ-CT) is a rapidly advancing technology that has been successfully employed to study flow phenomena in porous media. It offers an alternative approach to core scale experiments for the estimation of traditional petrophysical properties such as porosity and single-phase flow permeability. It can also be used to investigate properties that control multiphase flow such as rock wettability or mineral topology. In most applications, analyses are performed on segmented images obtained employing a specific processing pipeline on the greyscale images. The workflow leading to a segmented image is not straightforward or unique and, for most of the properties of interest, a ground truth is not available. For this reason, it is crucial to understand how image processing choices control properties estimation. In this work, we assess the sensitivity of porosity, permeability, specific surface area, in situ contact angle measurements, fluid-fluid interfacial curvature measurements and mineral composition to processing choices. We compare the results obtained upon the employment of two processing pipelines: non-local means filtering followed by watershed segmentation; segmentation by a manually trained random forest classifier. Single-phase flow permeability, in situ contact angle measurements and mineral-to-pore total surface area are the most sensitive properties, as a result of the sensitivity to processing of the phase boundary identification task. Porosity, interfacial fluidfluid curvature and specific mineral descriptors are robust to processing. The sensitivity of the property estimates increases with the complexity of its definition and its relationship to boundary shape.

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• We use synchrotron X-ray imaging to quantify the change in flow dynamics as the system transitions to steady-state. • We observed distinct dynamics during transient flow which would suggest that transient flow should be modelled with separate parameters. • We quantify the timescales for steady-state to be established for different capillary numbers and viscosity ratios.

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The wetting state is an important control on flow in subsurface multi-fluid phase systems, for example, carbon storage and oil production. Advances in X-ray imaging allow us to characterize the wetting state using imagery of fluid arrangement within the pores of rocks. We derived a model from equilibrium thermodynamics relating fluid coverage of rock surfaces to wettability and fluid saturation. The model reproduces the behavior measured in a water-wet, nearly all-quartz, Bentheimer sandstone imaged during steady-state imbibition. A shift in fluid surface coverage is observed when the rock is altered to a new wetting state with crude oil. In two multimineralogical (Berea) samples, one water-wet and the other altered with crude oil, the analysis of fluid surface coverage after imbibition revealed mineral specific wetting preferences only in the altered system. Clays and calcite preferentially alter to an oil-wet state, leading to mixed wettability in the rock. Plain Language SummaryThe movement of multiple fluid phases through the pores of rocks is central to many processes of scientific and societal interest, for example, CO 2 storage and oil production. When two or more fluids occupies rock pores, the way these fluids move strongly depends on the way the fluids interact with the mineral surfaces constituting rock pore walls. In general, the mineral surfaces prefer to be in contact with one particular fluid. This wetting preference controls the flow of these fluids across large scales in the subsurface. In this work, we propose a theoretical and practical approach to characterize this wetting preference. Our approach is based on the analysis of the interfaces shared by rock surfaces with each fluid. The extent of these interfaces depends on rock grains wetting preference. Since this preference can be modified by exposing certain rock samples to crude oil, we prove that the fluid-rock interfaces change accordingly in a rock constituted by a single mineralogy. Finally, we investigate mineral wetting preference, in a rock comprising multiple minerals. When previously exposed to crude oil, these minerals show a different wetting preference. This behavior is not observed when a sample of the same kind was not exposed to crude oil.

We use fast synchrotron X-ray microtomography to understand three-phase flow in mixed-wet porous media to design either enhanced permeability or capillary trapping. The dynamics of these phenomena are of key importance in subsurface hydrology, carbon dioxide storage, oil recovery, food and drug manufacturing, and chemical reactors. We study the dynamics of a water-gas-water injection sequence in a mixed-wet carbonate rock. During the initial waterflooding, water displaced oil from pores of all size, indicating a mixed-wet system with local contact angles both above and below 90 •. When gas was injected, gas displaced oil preferentially with negligible displacement of water. This behavior is explained in terms of the gas pressure needed for invasion. Overall, gas behaved as the most nonwetting phase with oil as the most wetting phase; however, pores of all size were occupied by oil, water, and gas, as a signature of mixed-wet media. Thick oil wetting layers were observed, which increased oil connectivity and facilitated its flow during gas injection. A chase waterflooding resulted in additional oil flow, while gas was trapped by oil and water. Furthermore, we quantified the evolution of the surface areas and both Gaussian and the total curvature, from which capillary pressure could be estimated. These quantities are related to the Minkowski functionals which quantify the degree of connectivity and trapping. The combination of water and gas injection, under mixed-wet immiscible conditions, leads to both favorable oil flow and significant trapping of gas, which is advantageous for storage applications.