Magma crystallisation provides scientists with volcanic crystal ball
Volcanos have been around since time on Earth began – and the devastation they can cause has hardly changed in the intervening 4.5 billion years. In the past month alone, untold damage has been wrought by volcanic eruptions – in Hawaii, Indonesia and Guatemala.
Of course, it is not possible to prevent volcanoes from erupting – and it would be extremely dangerous if you did. Volcanoes are a natural pressure release for the planet. If they were all blocked up, that pressure would continue to mount – and it has to escape somehow. The day that Earth’s volcanos – all 1,500 of them – fall silent, is the day the planet enters its death throes.
It’s also unrealistic to think that everyone living within the danger zone of a volcano – where they and their property are at risk should it erupt – should simply move. In fact, around one in 20 people live within this range of an active volcano.
And there are actually many benefits to living close to a volcano. Volcanic eruptions are responsible for bringing many minerals to the Earth’s surface. The soil around volcanoes is therefore highly fertile and good for crops.
So if volcanic activity can’t be stemmed and the people most at risk can’t be permanently relocated, what can be done to limit the devastation when a volcano erupts? Well, one way might be to predict more accurately the eruptions themselves, to allow for better disaster planning. So, how can this be done?
Inside the volcano
New research led by scientists at The University of Manchester may have brought us a step closer to the answer.
Mike Burton, Professor of Volcanology at the School of Earth and Environmental Sciences, worked with the team on a project studying the crystallisation processes that occur as magma makes its journey to the Earth’s surface. Magma is the molten rock that lies under the Earth’s crust. Once it erupts out, it is known as lava.
As magma erupts, it starts to crystallise. Prof Burton explains: “During eruptions, small crystals grow within magma and lava, and these can greatly change the way in which the magma flows: more crystals means that the eruption slows down, fewer crystals means the eruption speeds up.”
Due to the very nature of a volcanic eruption, the pressure and composition of the magma is in a state of flux, which makes studying this crystallisation difficult (not to mention the deadly risk of being close to an active volcano when it erupts). For this reason, models allow scientists to study crystallisation in magma in a safe environment. However, it has not previously been possible to watch the crystallisation process as it happens in real time, as the action has all been contained within a closed vessel that has to be cooled quickly before scientists can see the results.
Prof Burton’s team have now successfully conducted the first in situ 3D time-dependent observations of crystal nucleation and growth kinetics in a natural magma, with the results published in Nature Scientific reports. He says: “We set up a sample from a real eruption in a high temperature cell, and then performed X-ray CAT scans as we controlled the temperature of the magma. This allowed us to visualise the formation and growth of crystals, and measure how quickly they grow.
“These experiments produce data that we can use in numerical models to more accurately forecast the behaviour of volcanic eruptions.” Prof Burton goes on to explain how the team’s approach is “revolutionary” compared to previous experiments: “The novelty of our approach is that we can watch the crystals grow in 3D in real-time, and this opens an entirely new frontier in the study of magma crystallisation.” The new method lets the team collect hundreds of 3D images from just one experiment, allowing them to fully characterise the behaviour of magma during the crystallisation phase.
Armed with this new data, scientists will be able to develop the models that allow them to predict more accurately how lava will behave after a volcanic eruption. This could help with the delivery of better-informed disaster planning.
And Prof Burton believes that there are more potential applications of the approach, including mineral extraction and geological approaches. “We are very excited about the prospect of extending our studies to high pressures, which we will be doing in further experiments in 2018,” he concludes.
Words – Hayley Cox
The University of Manchester