The impact of magmatic volatiles on stability of subvolcanic reservoirs and eruptive style
Olivier Bachmann 1, Razvan-Gabriel Popa1, Christian Huber2
Affiliations: 1. Department of Earth and Planetary Sciences, ETH Zürich, Switzerland 2. Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, USA
Presentation type: Poster
Presentation time: Monday 16:30 - 18:30, Room Poster Hall
Poster Board Number: 35
Programme No: 1.7.22
Abstract
The presence of magmatic volatiles, particularly H2O and CO2, plays a critical role in the evolution of magma reservoirs, influencing depth of magma storage, size and recurrence intervals of volcanic eruptions, and eruptive style. As volatile elements exsolve from magmas, they can lead to crystallization, impacting the mobility of such magmas. They also form a compressible phase that significantly alters the mechanical behavior of reservoirs open to magma recharge. The changes in compressibility due to an exsolved volatile phase affects pressure conditions within the magma storage region, playing an important role in controlling the frequency of eruptions. Moreover, the existence of an exsolved volatile phase in the subvolcanic magma reservoir prior to eruption tend to maximize eruptive volumes, as the presence of gas bubbles fosters mobile magma to escape from its storage area. Finally, the exsolved magmatic volatile phase formed within the magma reservoir play a crucial role in the development of gas permeability during magma ascent in the volcanic conduit. This process is key to understanding the transition between effusive and explosive eruption styles, as permeability development due to bubble growth and coalescence in conduits allows for gas escape, which strongly reduces the explosive potential of eruptions. Therefore, the study of the amount and state of magmatic volatiles in magma reservoirs is key for understanding volcanic behavior and mitigating associated hazards.