IV. Volatile influences on eruption style, degassing, atmospheric chemistry and climate  

IV.6 Magma fragmentation and the production of volcanic ash

Joali Paredes*, University of Perugia; joali.paredes@studenti.unipg.it
Jonathan Castro, Johannes Gutenberg University Mainz; castroj@uni-mainz.de
Pablo Forte*, Johannes Gutenberg University Mainz; P.Forte@geo.uni-mainz.de
Ulrich Kueppers, Ludwig-Maximilians-University of Munich; u.kueppers@lmu.de

*Student Conveners

Fragmentation is a critical process in volcanic eruptions. Its occurrence determines whether or not a volcano will eject vast amounts of pyroclastic material into Earth´s atmosphere. During its ascent in the conduit, magma evolves due to changes in stress, temperature and composition, leading to important strain heterogeneities during flow and considerable variability in fragmentation processes. Understanding the causes and processes behind the disruption of a continuous volume of molten rock into a mixture of gas and particles is still one of the main challenges of modern volcanology, and yet it’s hindered by our inability to make direct observations of the fragmentation process. Qualitative and quantitative analysis of tephra particles can shed light on the physical and chemical processes acting both during its formation and as ash travels through the atmosphere. We seek contributions focused on tephra studies, that combine natural evidence with experimental, statistical and numerical approaches to understand: (i) generation mechanisms, (ii) fragmentation timescales and efficiency, (iii) post-fragmentation processes inside the volcanic conduit (e.g., sintering and rheomorphism) and (iv) variability in the results obtained from natural deposits, experimental studies and models. This session aims fostering multydisciplinary interactions and collaborations amongst field geologists, geochemists, petrologists, volcanologists, geophysicists, and numerical modelers.