March 3, 2024

I, Science

The science magazine of Imperial College

By looking at complex atmospheric dynamics, scientists have simulated how ash was transported from volcanic eruptions.

Now the sun’s out and we’re enjoying the start of summer, you might be looking forward to a relaxing holiday abroad. But eight years ago, thousands of tourists had their travel plans jeopardised by a dangerous complication: the Icelandic volcano Eyjafjallajӧkull.

Now, new techniques are offering ways to predict the impact of ash from volcanic eruptions with far more accuracy. By looking at complex atmospheric dynamics, and in particular wind direction, scientists have simulated how ash was transported from two eruptions in the Caribbean.

“The models predict the concentration of the thin layers of airborne ash that can affect aviation, like the Eyjafjallajӧkull eruption,” explains Dr. Jeremy Phillips, a volcanologist at the University of Bristol and co-author of a recent paper on the new technique.

Dr. Phillips’ team observed La Soufrière, a volcano on the island of Saint Vincent. Archives of detailed eyewitness accounts and field measurements from its last two eruptions, in 1902 and 1979, as well as the topography of the island and its setting in a flat ocean all help to interpret simulation models.

These simulations included the effects of the Caribbean trade winds which reverse direction at around five kilometers in altitude. Ash can get trapped in the layer between these winds, causing it to end up in some unexpected places.

“Sometimes people see evidence from the field, like aggregates, and make a connection, so that idea tends to become accepted. But actually, there are alternatives and sometimes those are simpler, but just haven’t been considered,” says Dr. Phillips. “By describing the wind profile in detail this enabled us to predict the formation.”

So how can models like this help us to avoid holiday disasters or serious impacts on sensitive infrastructure? Dr. Phillips suggests these simulations could help form part of the response to volcanic eruptions. Although the models take longer to run, they could be used for volcanic eruptions that are more sustained over around 12-24 hours.

Additionally, the same modelling technique could be applied to different volcanoes under different conditions, taking account of meteorological changes, varying levels of explosiveness and length of eruptions. These models can be made now and in the future be used straight away in the event of an eruption. “You could imagine having a whole library of different simulations you could pull off the shelf,” says Dr. Phillips.

Bridie Kennerly is studying for an MSc in Science Communication at Imperial College London

Banner Image: Mount St. Helens, John Pallister / Wikimedia Commons