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Bristol's hotspot (Nonesuch spring 2016)

Nonesuch Spring 2016

Topographic fringes from a TanDEM-X image pair, showing the thickness of new lava flows at Volcán Reventador, Ecuador. One complete colour cycle corresponds to 25m of new lava D Arnold, J Biggs, CEOS DRR Volcano Pilot

Nonesuch Spring 2016

Assisting with the monitoring of Paycaya in Guatemala using infrared spectroscopy to record gas emissions Luke Western (PhD 2013-)

Nonesuch Spring 2016

Dr Maria Elisa Balen conducting risk perception interviews near Cotopaxi, Ecuador Dr Ryerson Christie

13 May 2016

Other than meteors, volcanic eruptions are the only natural hazards to have potentially global consequences. But how much do we really know about what triggers an eruption, or what those consequences might be? Two world-leading volcanologists in the University’s Cabot Institute explain.

In 1995, after lying dormant for more than 300 years, the Soufrière Hills Volcano on the small Caribbean island of Montserrat, a British Overseas Territory, erupted. For the next five years, it sent fast-moving gas and rock flows across the island, and, in 1997, buried the capital city, Plymouth, under metres of debris. More than 8,000 people – two-thirds of the island’s population – were forced to leave their homes.

The disaster prompted the British government to call on Professor Steve Sparks FRS, from the School of Earth Sciences at the University of Bristol, for help. Sparks’ knowledge of how volcanoes behave – and, just as importantly, how they might behave – proved crucial for co-ordinating the effective evacuation of the island’s residents.

Today, the Soufrière Hills Volcano has become one of the most important and best-studied eruptions of its type, and more than 20 years later, the research Sparks and his colleagues embarked on in Montserrat still underpins the longest-running and most sophisticated volcanic risk assessment of its kind.

Sparks and his colleagues in Bristol’s Volcanology Research Group, headed by Professor Katharine Cashman FRS, AXA Chair in Volcanology, now represent one of the largest and most successful volcanology groups in the world. Last year, Sparks won the Vetlesen Prize (the Nobel Prize of the Earth sciences) for his contribution to the field, and in November, the group received the prestigious Queen’s Anniversary Prize for Higher Education in recognition of their outstanding research.

The group works closely with researchers from a range of other disciplines, including engineering, mathematics, history and social sciences, within the University’s Cabot Institute. Co-founded by Sparks in 2010, the Cabot Institute brings together world-class expertise to tackle some of the most pressing environmental challenges affecting how we live with, depend on and adapt to our planet.

'Our work falls broadly into two categories: hazard and risk,' explains Professor Cashman. 'For us, the terms have quite different meanings. "Hazard" describes fundamental volcanic processes – the probability of an eruption, the direction of lava ow or the volume of gas emissions. "Risk" occurs when those hazards intersect with people – with local, regional and global populations.'

The two categories are, of course, intrinsically linked: only by carrying out fundamental, curiosity-driven research can the team begin to understand the impact natural hazards have on life above the surface.

So, what makes a volcano erupt?

'That's the question children always ask when they learn about volcanoes,' says Cashman, 'and it’s very difficult to answer. One of the biggest challenges is that what triggers an eruption happens where we can't see it.

'However, volcanology is undergoing a scientific revolution, and the techniques we apply to our research are rapidly changing. We used to think that volcanoes such as the Yellowstone Caldera in the US produced large eruptions from a "vat" of melt below the surface. Recently this view has changed. We now view magmatic systems as vertically extensive and transiently connected regions of melt and (mostly) crystals, or solid particles.

'In fact, the magma chambers that feed volcanoes may be more akin to mushy snow and ice than smooth-flowing liquid. Importantly, "mush" is likely to produce different geophysical signals than melt, and thus we are rethinking our interpretations of volcano monitoring data.'

Working collaboratively to decipher how all aspects of the volcanic system interact – and respond to changes in the external environment – the group uses a combination of laboratory studies, geophysical and geological observations and satellite data. Additionally, studies that might once have been the preserve of volcanologists, petrologists or geophysicists now more often include experts from other disciplines too.

'Collaborating across disciplines helps us think about volcanic systems as a whole, and see how different pieces fit together,' Cashman explains. 'For example, we are working with statisticians on the probability of eruptions, and with applied mathematicians on the behaviour of lava flows, mudflows and volcanic plumes. We're also working with atmospheric scientists on the climatic impacts of eruptions, with social scientists on risk assessment and communication, and with historians on past eruptions.'

Can we predict when an eruption will occur?

Typically, before a volcano erupts, the ground may swell, and migrating magma may trigger tiny earthquakes and release gases. Scientists have used ground-based monitoring for a number of years to detect these subtle changes, but researchers at Bristol now measure these small deformations in the Earth’s surface using satellite-based techniques.

For example, Dr Juliet Biggs was studying the East African Rift, a 6,400km trail running through Djibouti, Ethiopia, Kenya and Tanzania, when she discovered that some of the rift’s 100 volcanoes weren’t as dormant as previously thought. These observations led to a significant grant from the Natural Environment Research Council for further study of the Main Ethiopian Rift – these volcanoes could seriously disrupt the densely populated cities of Addis Ababa and Nairobi, yet until recently, have gone largely unstudied.

In fact, more than 1,000 active volcanoes worldwide currently go unmonitored, either because of their remote location, the political climate, or because countries simply don’t have the money or the technology to observe them more closely. 'Using satellites is a big step forward in monitoring individual volcanoes,' says Cashman, 'and could pave the way for a global forecast system.'

What happens after an eruption?

Satellites aren't just providing new ways of forecasting natural hazards: they're also helping to monitor activity after eruptions too.

'Contrary to what most people believe, the UK does have a volcano problem,' says Cashman. 'It’s called Iceland.' In 2010, Iceland’s largest volcano, Eyjafjallajökull, sent a giant ash cloud across northern Europe, forcing the unprecedented closure of airspace, and costing the aviation and tourism industries hundreds of millions of pounds.

Since then, thanks to a seven-figure grant, Bristol’s Volcanology Research Group has been working closely with the Met Office to increase the UK’s resilience to the hazards posed by Iceland’s volcanoes. 'We're helping them better interpret satellite images, improve existing models of volcanic ash plumes, and track how ash is transported before settling,' Cashman explains. 'A volcano can erupt in a number of different ways and produce ash particles that vary in size, density and shape, affecting how an ash cloud will be dispersed.'

The potential impact of Icelandic eruptions on the UK extends beyond ash alone. In 1783, for example, a large lava ow eruption generated an acid fog that caused crop failure and increased mortality in many parts of Europe.

Will there be more volcanic eruptions in Iceland? 'The answer is certainly yes', says Cashman, 'but, as elsewhere in the world, we’re working hard to minimise their impact.'

Global perspective

Bristol has been the driving force for the Global Volcano Model, a free, online resource for researchers, community leaders, politicians and industry, co-founded by Professor Sparks in 2011.
‘The aim is to co-ordinate international activity and create an authoritative source of information,' he explains. 'One example of how Bristol has contributed is by providing data on the size and frequency of every volcanic explosion around the world. That data can be useful both for scientists, and for local and regional communities.'

Last year, Sparks delivered a synopsis of global volcanic risk to the United Nations, forming the basis of their Sendai Framework for Disaster Risk Reduction. He has also been involved in international discussions encouraging more governments to invest in risk reduction – preventative measures that are sustainable in the long-term – rather than simply ring-fencing money for emergency relief.

'Governments and policymakers tend not to look beyond the next election cycle,' says Sparks. 'But environmental strategies have to be long-term. Natural disasters will happen, and large eruptions can have global consequences, years into the future.'

History certainly offers some foreboding examples. In 1815, Indonesia’s Mount Tambora launched more than 12 cubic miles of gas, dust and rock into the atmosphere, blocking the sun and chilling much of the northern hemisphere. A year later, clothes froze to washing lines in north America; the highest summer temperature recorded in Spain was 15oC. Crops failed around the globe, and an estimated 70,000 people died from starvation or disease.

'An eruption on the scale of Tambora in today’s world would be devastating,' admits Sparks, 'and there have been even larger eruptions in the past. Yellowstone Caldera gets a lot of headlines. If it were to erupt today, it would cover most of north America and Canada with ash, with huge consequences for the global climate.'

Local impact

Yet even with comprehensive hazard and risk assessments, communicating the risks of an eruption can pose significant and surprising challenges, as social scientists from the Cabot Institute, led by Dr Ryerson Christie, have discovered.

In 2013, Christie and his team conducted hundreds of interviews with people living near Cotopaxi in Ecuador. Their research revealed that most inhabitants had actively relocated to the volcano, believing the area offered them better security than nearby cities. Existing evacuation procedures also required residents to cross areas depicted as dangerous in folklore, leaving many conflicted and confused about how to respond in an emergency.

Studies like these highlight the importance of taking local knowledge and beliefs into account when devising natural disaster educational tools, and the Volcanology Research Group is currently involved in a pilot project funded by the World Bank to develop jargon-free public information films to help some of the world’s most vulnerable communities.

'How our work supports emergency management is hugely important,' says Sparks. 'It’s about resilience: strengthening the capacity of communities to deal with eruptions when they happen. Yes, at its most fundamental, volcanology is about understanding how our planet works, but it’s also about saving lives and protecting people.

'Certainly for me, Earth sciences is the most important branch of science in the 21st century. Volcanoes are responsible for our atmosphere, our oceans, and our land formations – and the impact they have on our environment profoundly affects how nine billion of us are able to live on, and adapt to, our changing planet.'

Listen to the audio version (mp3)

Further information

Find out more about the work of Bristol’s Volcanology Research Group. Professor Sparks and other members of the Cabot Institute will also talk at a panel discussion event, ‘Living with volcanoes in the 21st century’, on Thursday 27 October in the Wills Memorial Building. 

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