Storage and Eruption of Mushy Magma Systems

Volcanic eruptions are a major natural hazard, affecting life, health and financial stability globally, with >800m people living within 100km of an active volcano. Large explosive eruptions can be devastating, causing tens of thousands of fatalities. Forecasting eruptive activity is the grand challenge of volcanology, but large eruptions are rare, so our ability to link geophysical observations of surface unrest to magma movements below the surface remains poor. There are two key questions: (1) how are large volumes of magma accumulated within the Earths crust? and (2) how are they subsequently mobilised for eruption? Magma is stored as crystal mush (a dense mixture of volcanic crystals and melt), that is too stiff to move and erupt. Understanding what controls its structure, and the mechanisms by which the mush can be released as eruptible magma, is therefore critical to identifying precursory signs of volcanic unrest. STEMMS introduces a transformative approach to the problem of magma storage and mobilisation prior to large volcanic eruptions, recognising that the micro-scale structure of a mush is fundamental to its subsequent macro-scale physical behaviour. The project brings together two new concepts: (1) The primary growth conditions of a mush control its grain-scale textures there is a critical link between magma crystallisation history and its subsequent physical behaviour. (2) A mush can be remobilised simply by growth of gas bubbles, with no external source of heat or eruption trigger the timing of volatile saturation is key. Thus, the way a mush is assembled critically determines its readiness to be erupted later. Together, these concepts will frame a new paradigm to define how mushy materials are mobilised before large volcanic eruptions. STEMMS will develop a new framework to interrogate the chain of events prior to large eruptions, which will change practices in the volcanology community and, ultimately, lead to improved eruption forecasting.