Catastrophic caldera-forming eruptions
The meticulous field work of Walker (1980), Self and Rampino (1981), Self et al. (1984), Rose and Chesner (1987), Hildreth and Mahood (1986), Branney (1991) and Druitt and Francaviglia (1992) demonstrated the destructive potential of catastrohpic caldera-forming eruptions, the largest known explosive eruptions in the geologic record. Using insights from this pioneering volcanology work and combining it with seminal studies on turbulent plumes by Morton et al. (1956) and analog experiments on volcanic jets by Carey et al. (1988), I conduct new analog experiments that test the effect of intermediate-sized "inertial" particles modeling pumice lapilli on the gravitational stability of jet columns modeling catastrophic caldera-forming eruptions. Inertial particles have a complex two-way momentum transfer coupling with the fluid they are suspended in and this coupling affects the ability of an eruption column to ingest and mix in the surrounding atmosphere, which is a crucial process for determining whether an eruption column collapses or rises buoyantly. Consequently, inertial particles play an important role in the dynamics of eruption columns and, in turn, determining the initial conditions of spreading ash clouds in the atmosphere, which serve as key input parameters for sophisticated ash transport models that predict hazards for air traffic and volcano-climate cooling effects on Earth's surface.
Are eruptions from linear fissures and caldera ring dykes more likely to produce pyroclastic flows?
Jessop, D. E., Gilchrist, J., Jellinek, A. M., & Roche, O. (2016). Are eruptions from linear fissures and caldera ring dykes more likely to produce pyroclastic flows?. Earth and Planetary Science Letters, 454, 142-153. https://doi.org/10.1016/j.epsl.2016.09.005
My previous work performed with Dr. David Jessop, Dr. Mark Jellinek and Dr. Olivier Roche investigated the effect of these particles when injected from annular vent geometries as expected to occur during catastrophic caldera eruptions. We have shown that these particles can enhance entrainment and in turn inhibit column collapse during Catastrophic Caldera-Forming explosive eruptions, whereas lower aspect ratio caldera ring vent geometries can do the opposite. The largest of these caldera-forming eruptions have not been witnessed with modern scientific instrumentation, therefore our understanding relies on analyses of their deposits, computer simulations and our analog laboratory experiments. Further analog experiments investigating this style of eruption can help us predict their effects on the global climate and in turn their threat to life on Earth.