Large‐Scale Experiments on Volcanic Processes

[1] Some of the least understood and most hazardous geologic processes involve complex multiphase flows, particularly those related to explosive volcanic eruptions. These phenomena inherently involve a wide range of characteristic length and time scales, as well as processes that are coupled across those scales in a range of flow regimes. For example, a pyroclastic density current's (pyroclastic flows and surges) behavior is governed in a complex way by the interactions between individual particles (∼10–4 to 101 meters, ∼10–1 to 101 seconds) and by turbulent mixing with surrounding air (∼10–2 to 102 meters, 1 to 102 seconds). Material properties within individual flows can vary over huge ranges; for example, when ascending magma interacts with groundwater in a volcanic conduit, the viscous melt and liquid water are transformed into brittle glass and steam.