About this Research Topic
Explosive volcanic eruptions result from the fragmentation of the magma below Earth’s surface into pyroclasts that are then dispersed by volcanic plumes and pyroclastic density currents. These eruptions may generate destructive pyroclastic falls and flows that have been responsible for the deaths of thousands of people. It is thus crucial to assess how magma breaks up into fragments and what happens to these fragments until they are deposited. Their size, shape, and density distributions as well as their evolution with time and space ultimately control how they will be transported, where they will be deposited, and the textural and geochemical record they preserve. The subterraneous nature of processes leading up to fragmentation and pyroclast dispersal as well as our current inability to see through volcanic plumes and pyroclastic density currents constitute important observational gaps.
Magma fragmentation creates a wide range of pyroclasts whose initial size, shape, and texture distributions remain poorly constrained. These pristine fragments of magma are however permanently exposed to changes until they are deposited. Various processes such as collisions, expansion, outgassing, agglomeration, sintering, healing, etc acting in the conduit, the plume, and/or the pyroclastic density currents as well as during final deposition alter the pyroclasts and transform their distribution. Moreover, if magma fragmentation has for long been thought of as the eruptive process that distinguishes explosive from effusive volcanic eruptions, recent studies have shown that effusive volcanism may also comprise phases of magma fragmentation.
We aim at collecting original papers focusing on magma fragmentation and the morphological, textural, and compositional evolution, transport, and deposition of newly formed pyroclasts, whether it is in the conduit, plume, pyroclastic flows, and fall or flow deposits. Papers looking at processes such as primary and secondary fragmentation, inter-particle collisions, pyroclast expansion, post-fragmentation outgassing, pyroclast agglomeration, sintering, and healing are encouraged, as well as studies examining the transport and deposition of tephra. Contributions originating from analysis of natural samples, experimental volcanology and petrology, and theoretical and numerical modeling are all welcome. We strongly encourage papers that emphasize links between processes and products.
Keywords: fragmentation, pyroclast, plume, conduit, pyroclastic density current, tephra, ash
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