Skip to content

Investigating vesiculation and crystallisation in volcanic systems: what we have learned in the last 10 years by combining 4D experiments, models and natural observations

Margherita Polacci

Abstract

Vesiculation and crystallisation play a fundamental role on magma dynamics and transitions in eruptive style in volcanic systems. They are time-dependent processes that introduce strong non-linearity into conduit flow dynamics, requiring real time studies to investigate such a dynamic system. In addition, vesiculation and crystallisation occur in a 3D system that cannot be quantified via snapshot experiments and/or 2D measurements. To better understand magma ascent and eruption dynamics at mafic volcanoes, in the last decade we have conducted series of 4D (3D space+time) experiments targeting crystal nucleation and growth and vesicle growth and coalescence at realistic magma storage and conduit conditions. The experiments were performed at two synchrotron facilities, DLS in the UK and ESRF in France, combining fast X-ray microtomography/radiography with experimental apparatus capable of reaching high T (≤ 1200°C) and crustal P (≤ 180 MPa), and using mostly the 2001 Etna and 2021 La Palma eruptions as case studies and their products as starting material. By implementing the tomographic data into a numerical model of the physical behaviour of magma in volcanic conduits, we were able to illustrate several mechanisms that control magma transport and eruptability, including crystallisation and dissolution kinetics, dendritic crystallisation and role of vesicle coalescence on degassing/outgassing. In this contribution I will provide an overview of the main results obtained, the scientific and technical challenges involved, and some perspectives on future investigations.