Taking the volcano’s pulse

March 7, 2017

Andrew McGonigle’s pioneering technology is helping scientists around the world to predict volcanic eruptions more accurately.

By Julian Cribb

Seven hundred million people live within the radius of destruction of one of Earth’s 600 active volcanoes. And 60 to 80 major volcanic eruptions occur somewhere on the planet each year, a frequency that has inexplicably doubled since the end of the 20th century.

These stark facts drive Rolex Laureate and volcanologist Andrew McGonigle, of the University of Sheffield in the United Kingdom, in his quest to help develop reliable volcano monitoring systems.

McGonigle received a Rolex Award in 2008 for a sophisticated system that deployed pilotless helicopters carrying scientific equipment to “sip” the invisible plume of gases escaping from the vents of volcanoes. Since, he says, violent eruptions are driven by gas and magma pressures, an impending explosion can be estimated by measuring the volume and ratio of carbon dioxide and other gases in the plume.

The techniques McGonigle has developed – combined with others that measure ground deformation (a sure sign of magma upwelling), changes in ground water composition, and seismic earth movements, along with other forms of gas analysis – have greatly improved the accuracy of volcanic monitoring and been adopted around the world to improve the safety of populations living near these unpredictable geological dragons. This has been further enhanced with the advent of low-cost drones to carry equipment into the crater, he says.

McGonigle acknowledges, however, that aerial sampling of volcanic gases has its limitations – primarily, that observations are limited by the flight endurance of drones. Consequently, he has committed part of his Rolex funding to pioneering a novel technology that can watch active volcanoes for long periods, using ultraviolet cameras to capture the plume from the ground or air.

Volume of gas

“The volcanic gases absorb ultraviolet light from the sky, and if you look at this through a specially adapted camera, it shows the gas as dark. From this imagery you can calculate the volume of gas being emitted,” he explains. “The camera can be mounted either on the ground, or in a drone. It is a simple point-and-shoot system that provides a real-time continuous feed of data about what is happening below ground.

“In effect, it means we are now able to take the volcano’s pulse. We can see it ‘breathing’ as the gas bubbles rise through the magma column and escape into the air, and observe the variations in these waves of gas. This has never been done before.”

The breakthrough in observing volcanic gases invisible to the human eye was achieved by McGonigle and his team adapting a lightweight sensor from a mobile phone to enable it to see in the ultraviolet, coupled with the cheapest micro-computer they could find. The result is a low-cost package that can be employed anywhere on the planet to dramatically improve the ability to understand underground conditions.

The technology has been trialled on Italy’s Mt Etna – which erupts very regularly – and since McGonigle is now on sabbatical in Sydney, Australia, he hopes shortly to test it in the Pacific “Ring of Fire”, on a cone such as Vanuatu’s Mt Tanna.

Leap forward

“We’ve so far demonstrated several different ways to monitor volcanic gases, which are being used by volcanologists in North and South America, Europe and Asia, but the ultraviolet imaging sensor looks like being an important leap forward. It is not a panacea but rather an important new component in the network of technologies, which volcanologists are using to study volcanoes and try to predict their behaviour. That network, and its ability to deliver early warning of possible eruptions, is getting better all the time.”

One advantage of the ultraviolet camera is that its gas-plume imagery can be coupled in real time with seismic monitoring of movements in the ground and magma, McGonigle says. This provides a far richer interpretation of what is happening where no human can go, deep into the volcano’s fiery throat.

It also enables gas signals from different locations to be integrated, giving a fuller picture of the volcanic processes.

“The problem is that no two volcanoes are exactly alike. They have widely different gas and magmatic chemistries and eruptive styles – from a constant, regular bubbling, like Stromboli, to a much rarer, vast explosion like the Plinian eruption of Vesuvius in AD79. This means we have to build up a large base of knowledge for each of the major classes of volcanic activity, to characterize the conditions that reveal when an individual source may be becoming dangerous.”

Eruption forecasting

McGonigle says that there have been significant developments in eruption forecasting, wherever in the world the scientific skills and instrumentation are sufficient. “It then becomes a question of how much warning you can give the local population – and whether the authorities can manage the evacuation of so many people in a timely and safe fashion.”

He cautions, however, that many active volcanoes are in developing countries lacking the geological expertise, equipment or constant monitoring to deliver effective warnings – and that there is an acute need for local authorities to have proper evacuation plans. Helping to provide universal surveillance of active cones through low-cost equipment like his ultraviolet monitor is one of his key ambitions.

”The continued growth of human populations in volcanic danger zones also adds to the urgency of improving our understanding of volcanic behaviour – which the Rolex Award is helping to achieve.”

Learn more about Andrew McGonigle

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