Research in the AVAST project was directed at identifying the signatures of different types of volcanic activity in the ash particles produced during eruptions. To do this, the researchers fragmented volcanic rocks in the laboratory using specialised apparatus to replicate natural processes occurring during an eruption. Rocks were rapidly decompressed using a shock tube apparatus (think of a champagne bottle for volcanic rocks at up to 900 degrees C) to simulate volcanic explosions that produce ash plumes, and tumbled in a rotary drum to investigate gravity-driven pyroclastic flows, and slid against one another to investigate fine particles created during some volcanic earthquakes, called fault gouge.
Research has focused on two case study volcanoes, Mt. Etna, IT and Volcán de Colima, MX. Field trips to collect natural samples and coordinate with local monitoring and hazard management agencies took place in 2017.
A major innovation in the project has been the imaging of ash particles using QEMSCAN®, a state-of-the-art automated SEM-based particle mapping procedure that can rapidly identify glass and common minerals in fresh volcanic ash. This allows image analysis of ash samples in a fraction of the time it would normally take using manual mineral identification. 90 samples were analysed by QEMSCAN during the fellowship, and the researchers gained in-depth immersive training in the technology.
The AVAST project has shown that both the composition of volcanic magma or lava and the type of volcanic activity change the properties of volcanic ash particles. During fragmentation the physical properties of the components forming the volcanic material (the minerals present in the magma, the volcanic glass and bubbles or pores) help to determine the size, shape and composition of the volcanic ash. Additionally, the AVAST project has investigated the rate at which ash is produced in pyroclastic flows and the way the rocks become smaller and smoother during flow, using a set of pumice samples from Laacher See, DE, the Azores, PT and Valentano, IT. This helps to understand the mobility of pyroclastic flows, often the most deadly volcanic phenomenon, and the importance of flows in generating volcanic ash.
Understanding of these intrinsic and fragmentation-specific controls can better define hazards from volcanic ashfall, helping to prepare and mitigate the effects on vulnerable zones, as well as improving ash cloud detection, monitoring and forecasting efforts. Associated project results have been disseminated in research papers, seminars and workshops; final project results are being prepared and these will be shared with local monitoring and civil protection agencies in Italy and Mexico via workshops.
