July 27, 2021

I, Science

The science magazine of Imperial College

Rachel David finds out why scientists are making jelly volcanoes

Predicting Nature’s fury

volcano iceland shutterstock_208502041In April 2010, an angry Icelander wreaked havoc in Europe. For around 2 weeks, over 10 million people were held hostage, and the economy suffered a huge dent. Its fury? A volcanic ash cloud that brought air travel to a standstill.

The impact from the eruption of Iceland’s Eyjafjallajökull volcano was felt deep in airlines’ pockets (an estimated $1.8bn in losses), but also by airports, hotels and industries that rely on air-freighted imports.  Many have speculated that the economy would not have been so severely affected had we been adequately prepared. A report by UCL’s Institute of Risk and Disaster Reduction concluded that the response was ineffective because it was entirely reactive, and recommended a better characterization of the potential disruption from future volcanic unrest.

aircraft grounded 4524257409_889f4db23c_b
Map showing planes in flight (yellow) and airports (blue crosses) on on Thursday 15th April 2010. There are no flights at all in Ireland, the UK, Holland, Denmark, Norway and Sweden. France, Spain, Germany and Poland were to follow.

Part of this would include better ways of predicting eruptions. But this is no easy feat. According to volcanologist Janine Kavanagh, from Liverpool University, volcanoes are highly individual, each with its own ‘normal’ behaviour, and predicting eruptions relies on detecting subtle deviations from this, mainly using satellite data that identify ground movements. Volcanoes are also not easy to study; not only are they dangerous, but their processes are hidden deep inside the ground.

However, Kavanagh and her collaborators have found a way around this: they use a scaled-down model of a volcano, made out of jelly, which, as it turns out “is a good analogue material [for] rock.” They then inject the jelly with a liquid that mimics magma – the molten rock that travels through the volcano’s ‘plumbing system’ to feed an eruption – and study its movement using a high-speed camera and laser.

sill diagram
Sill formation: Magma flows into existing rock formations through channels (dikes), along preexisting planes between sedimentary or volcanic beds or weakened planes in metamorphic rock, to produce a sill – a thin sheet-like body of magma paralleling the existing rock

They recently made a key discovery using this model. “We identified a big change in pressure in the system which was happening much deeper down, which nobody had recognized before,” said Kavanagh. Drops in pressure cause the release of gases that are part of magma, causing magma to explode, “like taking the lid off a Coca Cola can”. In this case, the pressure drop occurred when a type of ‘magma chamber’ called a sill was formed deep within the volcano, leading to an eruption. Kavanagh hopes that measuring these deep pressure changes will complement, and improve, current prediction methods.

It is impossible to tell whether this information would have been useful in 2010, although it is notable that the magma feeding Eyjafjallajökull’s eruption was coming from deep inside the volcano, rather than close to the surface. But better prediction methods like this, along with more efficient response systems, will certainly help us be better prepared for future bouts of fury.

Rachel David is studying for an MSc in Science Communication

Images: Volcano in Iceland by Gardar Olafsson (Shutterstock); North European Aircraft Grounded by Icelandic Volcanic Ash / Dust Cloud by Dominic Alves (Flickr, Creative Commons); Sill diagram (Wikimedia Commons)

Citation: Kavanagh, J.L. et al. (2015) The mechanics of sill inception, propagation and growth: Experimental evidence for rapid reduction in magmatic overpressure. Earth and Planetary Science Letters
421, 117–128.