Volcanic ash is generated during explosive activity, but the hazard does not end when an eruption stops. Ash deposits can be resuspended during strong winds for many years after primary deposition. Airborne volcanic ash poses a significant hazard to aviation and to human health. To mitigate against ash hazards, the London Volcanic Ash Advisory Centre (VAAC) at the UK Met Office provides forecast guidance concerning the location of volcanic ash in the atmosphere and the likelihood of resuspension. Forecasts are generated using the atmospheric dispersion model NAME (Numerical Atmospheric-Dispersion Modelling Environment).
The cold desert climate, strong winds, complex topography and lack of vegetation in Iceland promote exceptional rates of erosion. Source areas used for the London VAAC forecasts currently represent ash deposits from the eruptions of Eyjafjallajökull in 2010 and Grímsvötn in 2011, which were identified immediately after the events. However, these source areas and their properties are continuously changing through time, as the deposits are reworked and redistributed. In this project, you will explore how volcanic ash deposits change through time in southern Iceland to target the following objectives:
(1) Identify the long-term source areas of resuspended volcanic ash in Iceland, and their physical properties, through detailed fieldwork and compositional analyses;
(2) Investigate how variations in key parameters such as soil moisture content and vertical size segregation of particles affect threshold wind friction velocities through controlled experiments;
(3) Evaluate how variations in these source parameters affect the ability of NAME simulations to reproduce case study resuspension events.