Wind-remobilisation processes of volcanic ash. Consensual Document

Abstract

Explosive volcanic eruptions can eject large quantities of tephra into the atmosphere that can be dispersed and deposited over wide areas. Whilst the hazardous consequences of primary tephra fallout are well known, subsequent remobilisation of ash by aeolian processes can continue to present an underestimated hazard on timescales of months to even millennia after the eruption. Although wind-remobilisation of ash was first recognised following the 1980 eruption of Mt. St. Helens, USA, ash remobilisation events in recent years, from the deposits of multiple volcanic eruptions (e.g. Grímsvötn, Iceland; Cordón Caulle, Chile; and Mt. Katmai, USA), have highlighted the high frequency of the phenomenon and the potential consequences for human infrastructure and health. Consequently, more than fifty scientists, including staff from volcano observatories and volcanic ash advisory centres (VAACs), and academic researchers from fields such as volcanology, aeolian processes and soil sciences, convened at the Bariloche headquarters of the Argentinian National Institute of Agricultural Technology (INTA) to discuss the current ‘state of the art’ for monitoring, modelling and understanding ash remobilisation and future issues that need to be addressed.