VOLCANIC ASH: AN AGENT IN EARTH SYSTEMS

Volcanic eruptions are an unavoidable natural hazard and their impact can be local, regional as well as global depending on the eruptive style. Ash particles are a common product of volcanic eruptions. Upon transport and deposition, ash poses a range of hazards to human and animal health, air traffic, infrastructure (e.g., power blackout, building collapse) and agriculture over variable time scales.

Ash is a descriptive and non-genetic term. Ash refers to a grain size of particles (< 2 mm) that can be generated by primary processes such as 1) bubble burst due to gas expansion, 2) magma rupture at high shear rates, 3) abrasion from friction and collision, 4) magma-water interaction, 5) crystal disintegration, and modified during transport. Such processes concur in determining the role of volcanic ash as an important agent in Earth systems. Understanding the generation of ash is vital to hazard assessment. Our knowledge and understanding of the changes to or due to volcanic ash after its generation are rudimentary. Here, we present an overview of the processes volcanic ash is exposed to or catalysing.