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How geological reality can help us propagate magma intrusion models into the future.

Sam Poppe1

Abstract

Understanding magma propagation mechanisms and ascent paths towards the surface is essential in volcano eruption forecasting and characterisations of volcanic and igneous plumbing systems (VIPS). Forward models reveal dominant mechanisms of magma propagation below the surface. Those forward models then inform numerical inversions of geophysical data. The majority of those models assume simplified theoretical laws of fluid dynamics and rock mechanics. They assume that magma propagation trajectories can be satisfactorily described by the opening of a tensile crack in a linearly-elastic crust. This presentation will show that such models ignore complex, but essential, magma-rock interactions observed in recent geological and experimental studies. We have shown that dike trajectories can be guided by pre-existing structural fabrics, that intrusion tip geometry and progressive host rock damage affect changes in propagation mode over time, that standard inversion methods fail to accurately estimate parameters of analogue intrusions from experimental surface displacements, and that simulating dynamic fracturing in host rocks during magma propagation is essential in capturing realistic patterns of host rock displacement, stress and strain. These findings should motivate our community to increase investigating the role of geological complexities in steering intrusion trajectories to drastically improve magma ascent models.