Using Mathematics to Understand Volcanoes

20 May 2013

Using Mathematics to Understand Volcanoes

Unravelling the mysteries of the world around us is all in a day’s work for Victoria University researcher Dr Mark McGuinness.

This week, the applied mathematician will give a lecture in Hamilton titled ‘Erupting rocks and dusts’ where he will explain how mathematical equations are helping scientists understand the behaviour of rock and dust in the ‘throat’ of volcanic eruptions.

Dr McGuinness, whose career has involved analysing the unique properties of Antarctic sea ice and helping solve industry-related mathematical problems, such as accurately measuring the weight of fruit on conveyor belts, says he accidentally became interested in volcanoes.

“It all started by chance during a sabbatical at the University of Limerick where I met a German volcanologist, Dr Bettina Scheu, who was giving a talk about her experiments with exploding rocks.

“During some eruptions, rocks and gases are subjected to incredibly high pressures which cause them to rip apart. But, when scientists replicated this scenario in lab experiments, they found that the rocks didn’t explode as expected.

“That’s when I became interested because, by using a high speed camera which films at 10,000 frames per second, the experiments revealed that the rocks were fragmenting in layers or slabs, rather than exploding into many tiny pieces.” 

To figure out why, Dr McGuinness and fellow mathematicians from Limerick and Oxford Universities developed equations to explain how gas moved through the rock during periods of extreme pressure.

These showed how gas flow interacts with magma in volcanoes and demonstrated how changes in the gas pressure at the surface of volcano penetrate through the rock inside.

When Dr McGuinness returned to Wellington, a conversation with volcano expert Professor Colin Wilson, who mentioned that dust behaves in the same way but at much lower pressures, added an extra element to the research.

“It’s very interesting work,” says Dr McGuinness.

“Although volcanic eruptions don't occur with the same frequency as other natural phenomena, such as earthquakes, the impact they can have is enormous.

“For example, the Icelandic volcano eruptions in 2010 caused massive disruption to air travel in the Northern Hemisphere.

“Here in New Zealand, geological evidence shows areas of the North Island have experienced eruptions which generated pyroclastic flows. These types of eruptions can have a devastating impact on the immediate environment, as currents of hot gas, rock and volcanic ash fall from the sky, or travel along the ground at speeds of up to 700 kilometres per hour.

“So, gaining a better understanding of the processes which occur during eruptions is important and it’s exciting to be able to contribute to that knowledge.”

Dr McGuinness’s Hamilton lecture is part of the Royal Society of New Zealand’s 10x10 lecture series.

Public lecture: ‘Erupting rocks and dusts’
7.30pm, Wednesday 22 May 2013.
Room S.G. 01, S Block, Gate 8, University of Waikato, Hamilton 3240

Further details are available through the Royal Society of New Zealand website: http://www.royalsociety.org.nz/events/10-x-10-lecture-series.

ENDS

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