Roscoe, Matt and James, Michael and Lane, Stephen and Tuffen, Hugh (2023) How do bubble-bubble and bubble-conduit interactions affect gas mass transport in a magmatic conduit? PhD thesis, Lancaster University.
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Abstract
As magma ascends, the bubbles that develop within it affect eruption style and, thus, understanding the possible configuration of bubbles in volcanic systems ultimately helps in mitigating volcanic hazard. While conduit models exist to describe the development of gas bubbles in basaltic systems, these do not take into consideration the effect of bubbles acting as groups on length scales comparable to multiple bubble diameters, nor do they consider the impact of non-vertical magma conduits. These effects were explored using a series of analogue experiments to identify and begin to quantify bubble grouping behaviour in a viscous liquid and the effect of inclining the constraining walls of a gas bubble-viscous liquid system. The main findings were that 1) bubbles have a tendency to self-organise into groups of greater bubble number density, 2) groups of bubbles act together such that their rise speed is typically 2-5 times greater than the buoyant rise speed of individual bubbles, 3) bubble interactions tend to result in vertical size stratification, and 4) the inclination of a conduit radically alters the spatial distribution across the width of the conduit even at low (