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Departmental Newsletter Autumn 2019

Spotlights: National Student Survey satisfaction 100%; Meet Dr Emma Liu, the volcanologist; The 1831 eruption of Babuyan Claro that never was; Amazing Fieldwork - Etna 2019; MOSAiC - a year-long city on sea ice, the Arctic science expedition; Journey to the centre of the Earth; Ocean Ecosystem after dinosaur killing asteroid collision; Expedition to Ol Doinyo Lengai Volcano,Tanzania; Martian landslides not conclusive evidence of ice; George Bellas Greenough & The Map that Changed the World; Festival of Geology
Earth Sciences lecture

Update from Prof Paul Upchurch, Head of Department

There have been a number of important developments. We have completed an entire hiring round, resulting in the appointment of three new lecturers; bringing the total number of staff appointments to eight. We have secured three major NERC grants and five papers have been published in Nature. Finally, having achieved a 95% overall satisfaction rating in last year’s National Student Survey, this year we achieved 100%! Lots to smile about!

R/V Polarsern Arctic ice city

The Arctic Science Expedition - a year-long city on sea ice

The MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate): Prof J. Stroeve, Dr M. Tsamados & PhD Student, R. Mallett are taking part in what could be the largest-scale Arctic research expedition ever planned when RV Polarstern is deliberately lodged into sea ice to drift past the North Pole. They will be working alongside scientists from 17 countries to understand the fastest changing environment on the planet.

Student Experience: NERC PhD student.

Etna 2019 image of the summit

Through my interest in volcanoes I have become involved with some amazing fieldwork taking place at Etna, one of the most active stratovolcanoes in the world.

Meet the Staff: Dr Emma Liu.
 
Emma Liu image

Emma’s life-long love for volcanoes, focuses on researching volcanic gases and the use of drone technology to obtain better gas samples. 

Hazard Centre: Babuyan Claro 1831 eruption.
 
Babuyan Claro volcano

The largest climate forcing eruption of the nineteenth century that is believed to have contributed to delaying the end of the Little Ice Age… never happened .

Press Release: Ecosystems after mass extinction.

Microscopic nannoplankton fossils. Credit: Samantha Gibbs/Paul Bown
By reducing biodiversity today, we run the risk of losing our critical ecosystem players, whose importance we have yet to fully appreciate.

Research: Martian landslides.

Noctis Landslide  Credit NASA/JPL-Caltech/University of Arizona/HI-RISE
Giant ridges on the surface of landslides on Mars could have formed without ice, challenging their use as unequivocal evidence of past ice on the red planet,

Outreach: Why do we care about the Earth’s core?

Painting of fluid orange and black colours, photographed by Paweł Czerwiński via unsplash.com.
Well, for a start, the outer core is the source of our magnetic field which protects us from the harmful rays of the sun.

Events: Festival of Geology

Festival of Geology

An event designed for everyone interested in the Earth & its origins. A day full of talks, exhibitions, rocks & fossils and a chance to take a tour of our department.

PhD News: Expedition to Tanzania.

Expedition to Ol Doinyo Lengai Volcano, Tanzania.
The plan was simple... stretch a rope across the wide gaping hole at the summit of the volcano and use pulleys to send cocktail shakers into the open lava lake.

Alumni News: The Map that Changed the World

Greenough maps
Next year sees the bicentenary of the publication of Greenough’s map  Greenough himself can be viewed as a founding father of UCL Earth Sciences.

 


Update from Prof Paul Upchurch, Head of Department.

Since my last contribution to this newsletter, there have been a number of important developments. In particular, we have gone through an entire hiring round, resulting in the appointment of three new lecturers. I would therefore like to welcome Emma Liu, Martin Homann, and Peter Irvine to the Department. Emma and Martin have officially started with us, and Peter will join us in the New Year. We are particularly excited about the new research strengths they bring to the Department: Emma uses drones to capture data on volcanic emissions; Martin is a sedimentologist with an interest in early life and Precambrian environments; and Peter works on ‘solar engineering’ approach’s to modifying our atmosphere to offset the effects of rising Co2. While I retain my own fondness for Blue Skies research (what else is a dinosaur palaeobiologists going to do?), I’m delighted that we have been able to take on new lecturers in fields that are of direct relevance to society’s needs and open up new avenues for impactful research.

In other areas, the Department continues to perform very well. I would like to congratulate Pieter Vermeesch, Michel Tsamados and Alex Song for their recent successes in obtaining major NERC grants. We have also seen the promotion to Associate Professor of Dominic Papineau, and to full Professor of Chris Kilburn. And in time for the Research Excellence Framework exercise (deadline this time next year), our staff have outdone themselves by producing a series of high profile papers in journals such as Nature (e.g. congratulations to Paul Bown, Ana Ferreira, Graham Shields, Andy Thomson and Dominic Papineau on this front). Finally, having achieved a 95% overall satisfaction rating in last year’s National Student Survey, I am delighted to report that this year we achieved 100%.

Before becoming Head of Department, my heaviest teaching and admin loads were always in the autumn term. I can remember both the enjoyment of teaching a new cohort of students, combined with anticipation of a well-earned rest over Christmas. Now, my schedule as HoD is somewhat different, but I imagine that most other staff and students also feel that Term 1 is tough at times. While I am sure none of us can get enough of the Earth sciences, a rest in a few weeks’ time will be very welcome. Given our ongoing successes, I think we can all put our feet up at Christmas in the knowledge we’ve had a very good year. Merry Christmas everyone!

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The Arctic Science Expedition - a year-long city on sea ice.

The MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) : Prof Julienne Stroeve, Dr Michel Tsamados and Robbie Mallett PhD student  are taking part in what could be the largest-scale Arctic research expedition ever planned when RV Polarstern is deliberately lodged into sea ice to drift past the North Pole. 

The scientist will be on board for two months, working alongside up to 600 international scientists and crew from 17 countries as part of this major international effort to better understand the fastest changing environment on the planet. Robbie Mallett and Dr Michel Tsamados will be aboard Russian icebreaker on the way to the Arctic to help build a "city on ice" and take part in the 6-week MOSAiC School 2019.  Professor Stroeve will investigate the depth and density of the layer of snow which covers arctic sea ice to see if the radar technology used by satellites, such as the European Space Agency (ESA)'s CryoSat-2, is accurately measuring sea ice thickness from space.

Understanding how far the radar actually penetrates into the overlying snow cover will improve data on sea ice thickness and density, which currently relies on information collected in the 1980s. Since then, the total area in the sea ice cover has declined and there is now a larger proportion of first-year sea ice in the Arctic Basin. Newer ice contains more salt than ice compacted over many years and may affect the radar signal returned to the satellite. "Because sea ice is an important indicator of climate change, plays a fundamental role in the Arctic energy and freshwater balance, and is a key component of the marine ecosystem, it is essential that we improve the accuracy of thickness measurements from satellites. We also hope improved data will give us a stronger steer on how sea ice thickness is changing from year to year and over the long-term," said Professor Stroeve.

MOSAiC radar equipment

Image: dual KA/Ku band radar setup on ice and collecting data.

The project will collect data from the autumn freeze-up, through winter snow metamorphism and summer melt using the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) drifting station. Spearheaded by Germany's Alfred Wegener Institute, the €120 million MOSAiC mission aims to answer questions about the Arctic climate system and how it affects global climate models, including investigating why the region is warming twice as fast as the global average.

It is among the first missions of its kind since the 1890s, when Norwegian explorer Fridtjof Nansen attempted to reach the North Pole by drifting in a ship locked in ice. Nansen had to abandon his ship when he realised he had gone off track, but the ship itself made it across the ice cap intact and the expedition resulted in breakthrough scientific discoveries about the Arctic and weather patterns.

Julienne Stroeve talks about the MOSAiC Expedition

My main interest is understanding the behaviour and influence that volatile species, mostly carbon and hydrogen, have throughout the mantle. Currently I am focused on the role that hydrogen plays in controlling mantle geodynamics, through investigating its affect on the strength of mantle phases."
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Lauren Cox, NERC PhD Student

Amazing Fieldwork at Etna, Septemeber 2019

I have just started my second year on the NERC DTP program through which I am investigating the relationships between seismic waves and melt distribution in volcanic systems, with James Hammond and David Dobson. We are currently working on building representative 3D grain-scale models of melt systems which can then be tested, and you’ll most likely find me in the basement labs, playing with epoxy!

Through my interest in volcanoes I have become involved with some amazing fieldwork taking place at Etna, one of the most active stratovolcanoes in the world. John Murray (The Open University) is a geophysicist who has been collecting ground movement data from Etna for 50 years, and this September marked his 80th research trip. I joined him for the third time this year, helping with dry tilt readings, setting up and recording of GPS measurements, and being ‘Chief of Staff’, which primarily involves holding the measuring staff used in determining ground height during precise levelling.

Since the last trip a year ago, three eruptions had occurred. The first in December 2018, when two fissures trending NNW-SSE opened below the Southeast Crater. Five months later a further fissure opened to their west. All three fissures produced lava flows towards the Valle del Bove, a collapsed basin located to the east of the summit. A final eruption occurred on July 19th from the Southeast crater, during which lava flowed south and blocked off the road around the summit- the first but not the only obstacle faced during the trip.

Etna 2019 images of the summit
Image: Precise levelling at the summit the summit (left); GPS tripod station on the northern flank (right)

Just prior to my arrival on September 8th, explosive activity from the Bocca Nova crater was heard by the current field team and evidence of a phreatic explosion during a thunderstorm involving old material was discovered at the Northeast crater. By the time my stint began, the Northeast crater activity had become strombolian and we were treated to some breathtaking views of bombs flying through the air and shockwaves warping the clouds, accompanied by a soundtrack of explosions every second. By the 12th September strombolian activity had begun at the Voragine crater, located between the Northeast and Bocca Nova craters. This meant that activity at all four craters had now occurred within two months and three of the four had shown activity within a week.

Such volcanic activity is wonderful to watch but not ideal for collecting ground deformation measurements. The aims of the trip were to measure deformation along a 70 km loop over the summit and flanks of Etna using the precise levelling technique, conduct GPS measurements using a network of over 70 stations, and collect readings at over 20 dry tilt stations, all within six weeks. Data collection was hampered from the start by the July lava flow, which meant that to access the northern side of the volcano we had to drive an extra hour each way around the outside of the park, rather than straight over the summit from our base in the south. Travel was further hampered by a tyre puncture- a hazard of driving over aa lava! The range of the ejecta being thrown out during the eruptions prevented us from accessing the GPS stations at the summit, but we did manage to complete the levelling loop, despite seismic tremors sometimes making reading the staff height with the level tricky. Initial results showed some considerable vertical movements, more than 10cm subsidence in places, and I am looking forward to seeing the final results.

Further reading:

Murray, J. B. (2019) ‘The cryptic summit graben of Mt. Etna volcano’, Journal of Volcanology and Geothermal Research, Vol 387, Web. DOI

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Meet Dr Emma Liu, Lecturer & Leverhulme Early Career Research Fellow in Volcanology 

First-year students Ningwei Ma, Victoria Spokes Mysa Alia Musa, Jiang Pan and Zakary Hansen met up with Emma in October to discover all about her research

Emma’s passion for volcanoes had begun at age 6, after seeing the aftermath of the eruption of Mount St. Helens (US) on a family holiday. This has fueled Emma’s life-long love for volcanoes, leading up to her current research, which focuses on volcanic gases and the use of drone technology to obtain better gas samples.
Emma’s day-to-day work often consists of writing with a cup of coffee for half the day and working in the lab with her UAVs (unoccupied aerial vehicles) on the other half, alongside her teaching duties of course. Besides staying in the office, Emma’s work allows her to go on adventures too; she has visited many unusual locations for her research. For example, a field trip to Iceland enabled her to investigate how volcanic ash is formed during Icelandic eruptions. She found that ash deposits from eruptions up to several years prior were still being remobilised by large wind storms. This observation then fed into a project researching the ash-depositing sites and air-quality prediction. Among her experiences, field work is rarely straightforward and the team always faces many difficulties, particularly concerning the instrumental and logistical aspects. To be more specific, instruments used to collect data often work perfectly in labs yet can shut down unexpectedly when placed in extreme environments. Besides, field work often takes place in challenging environments, which can make the logistics of travel and transport difficult at times. The various contingencies prepared for all possible scenarios are crucial as Emma and her colleagues might not have another chance to visit the same location again.

An eruption at Eyjafjallajokull in April 2010 sent a huge ash cloud across Europe

Image: An eruption at Eyjafjallajokull in April 2010 sent a huge ash cloud across Europe.

Icelandic eruptions provided a lot of valuable research insights for Emma, including her proudest findings—the interaction of glacial water with magma during ‘hydromagmatic’ eruptions can produce more volcanic ash than comparable ‘dry’ eruptions. Rapid cooling of magma on contact with glacial water can cause it to fragment like glass into fine-grained and jagged ash. Consequently, even a moderate Icelandic eruption occurring in the vicinity of a glacier can exert unexpectedly large impacts on the world.
Emma’s current research focuses on using drones to measure volcanic gases remotely, at highly active but otherwise inaccessible volcanoes. Previously, these measurements would have only been possible with the use of satellites or direct sampling from around the volcano’s rim. She assured us that in some cases drones are more effective and considerably safer than the traditional methods. Emma told us how this research project was part of a ‘bigger’ global effort, coordinated by the Deep Carbon Observatory,  working towards improving our understanding of the contribution volcanoes make to global carbon flux.

Emma Liu (left) and Kieran Wood with a multi-rotor drone on Rabaul Volcano

Image: Emma Liu (left) and Kieran Wood with a multi-rotor drone on Rabaul Volcano.

In May 2018, Emma received the honour of being awarded the L’Oreal for Women in Science fellowship. Recently, she led a team of 30 members on an expedition to Papua New Guinea. Emma has always deeply appreciated her career which not only enriches her experience, but allows her to interact with a diverse range of people from all over the world, including many like-minded female researchers. With all of her past work in mind, she considers her ultimate goal as ‘to help local observatories potentially forecast changes in volcanic activity.’ Though there is still a long way to go, by collecting volcanic gases, tracking magma activities, making global observations and identifying patterns, “we are getting closer”, she says. In the future, people may accurately forecast volcanic eruptions the same way we can forecast the weather today. Should she and her colleagues succeed in their goal, it will be a significant breakthrough for volcanology.

Above and Beyond: Measuring volcanic emissions with drone technology
Science is constantly evolving. Knowledge taught in lectures is only the current state of understanding, so never be afraid of questioning the world. A piece of advice from Emma, “Think BIG and question everything!”

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News from the UCL Hazard Centre: The 1831 eruption of Babuyan Claro that never was by Christopher Garrison, PhD student

Volcanic eruptions that produce sulphate aerosols in the stratosphere are important climate forcing events. One of the largest climate forcing eruptions of the nineteenth century took place in 1831. It is believed to have contributed to delaying the end of the Little Ice Age, and hence the onset of anthropogenic warming, till 1850 [1]. The eruption has been attributed to Babuyan Claro, a volcano located on a small and remote island of the same name in the Philippines. It appears in the Smithsonian Global Volcanism Project (GVP) database (the standard chronology of historical volcanism) as an explosive eruption which ‘definitely’ injected ash and gas into the stratosphere. Our recent studies, however, show that there never was an 1831 eruption of Babuyan Claro [2].

Starting from the present day we traced chains of references to the 1831 eruption of Babuyan Claro through earlier and earlier generations of eruption catalogues and other volcanological works. We found that they all ultimately depended on a single primary source. During a round-the-world voyage, the German botanist F.J.F. Meyen sailed past the island of Babuyan Claro on the morning of the 7th August 1831 and, looking at a volcanic cone at the western end of the island, recorded in his account that it was ‘probably the volcano which only a short time ago had caused the inhabitants of the island to flee.’ It is evident that he hadn’t witnessed any eruption himself but had gleaned his information from some earlier source. In fact, we found independent evidence suggesting that he was probably (mistakenly) referring to an eruption which is reported to have taken place in 1681, when a visiting Roman Catholic priest is supposed to have persuaded the inhabitants of the island to remove themselves to the mainland, leaving the island abandoned until the second half of the nineteenth century. Nevertheless, on the basis of a later author assuming that ‘a short time ago’ must mean months at most and that ‘causing the inhabitants to flee’ must mean that the eruption was a ‘great’ one, a false record of a ‘great’ eruption of Babuyan Claro in 1831 did enter the literature. At the hands of later authors making their own compounding assumptions about this false record, the description of the magnitude of this imaginary eruption grew and grew until it reached that listed in the present-day GVP data-base record. Accordingly, we concluded that there is no evidence to support a belief that there ever was an 1831 eruption of Babuyan Claro and we identified it as a false event.

[Figure: Image of Babuyan Claro island. Caption: ‘The island of Babuyan Claro. Image reproduced with permission: Jonathan Torgovnik / Getty Images News / Getty Images.’]

[Figure: Image of Babuyan Claro island. Caption: ‘The island of Babuyan Claro. Image reproduced with permission: Jonathan Torgovnik / Getty Images News / Getty Images.’

The climate forcing eruption of 1831 must therefore have taken place elsewhere. It is important for both volcanology (for example, in terms of hazard assessment) and climatology (for example, in terms of the accurate reconstruction of the forcing effect of the eruption in climate models) that it is correctly identified. We are currently studying what we believe to be a very likely candidate. Beyond the events of 1831, though, this example also again underlines the importance of the careful analysis of primary sources when dealing with historical eruptions and other geophysical events.

References:

[1] Brönnimann, S., Franke, J., Nussbaumer, S.U. et al., Last phase of the Little Ice Age forced by volcanic eruptions., Nat. Geosci. 12, 650–656 (2019) DOI

[2] Garrison, C.S., Kilburn, C.R.J. & Edwards, S.J., The 1831 eruption of Babuyan Claro that never happened: has the source of one of the largest volcanic climate forcing events of the nineteenth century been misattributed?, J Appl. Volcanol. (2018) 7: 8. DOI

 

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Martian landslides not conclusive evidence of ice.

Detailed three-dimensional images of an extensive landslide on Mars, which spans an area more than 55 kilometres wide, have been analysed to understand how the unusually large and long ridges and furrows formed about 400 million years ago.

The findings, published today in Nature Communications, show for the first time that the unique structures on Martian landslides from mountains several kilometres high could have formed at high speeds of up to 360 kilometres per hour due to underlying layers of unstable, fragmented rocks. This challenges the idea that only underlying layers of slippery ice can explain such long vast ridges, which are found on landslides throughout the Solar System.

First author, PhD student Giulia Magnarini (UCL Earth Sciences), said: “Landslides on Earth, particularly those on top of glaciers, have been studied by scientists as a proxy for those on Mars because they show similarly shaped ridges and furrows, inferring that Martian landslides also depended on an icy substrate. “However, we’ve shown that ice is not a prerequisite for such geological structures on Mars, which can form on rough, rocky surfaces. This helps us better understand the shaping of Martian landscapes and has implications for how landslides form on other planetary bodies including Earth and the Moon.”

The team, from UCL, the Natural History Museum (London), Ben Gurion University of Negev (Israel) and University of Wisconsin Madison (USA), used images taken by NASA's Mars Reconnaissance Orbiter to analyse some of the best-defined landslides remotely.

Annotated image of Martian landslide
Image: Martian landscape annotated with London and global landmarks for scale (credit: Giulia Magnarini / NASA)

Cross-sections of the Martian surface in the Coprates Chasma in the Valles Marineris were analysed to investigate the relationship between the height of the ridges and width of the furrows compared to the thickness of the landslide deposit.

The structures were found to display the same ratios as those commonly seen in fluid dynamics experiments using sand, suggesting an unstable and dry rocky base layer is as feasible as an icy one in creating the vast formations.  

Where landslide deposits are thickest, ridges form 60 metres high and furrows are as wide as eight Olympic-sized swimming pools end-to-end. The structures change as deposits thin out towards the edges of the landslide. Here, ridges are shallow at 10 metres high and sit closer together.

Co-author, Dr Tom Mitchell, Associate Professor of Earthquake Geology and Rock Physics (UCL Earth Sciences), said: “The Martian landslide we studied covers an area larger than Greater London and the structures within it are huge. Earth might harbour comparable structures but they are harder to see and our landforms erode much faster than those on Mars due to rain".

“While we aren’t ruling out the presence of ice, we know is that ice wasn’t needed to form the long run-outs we analysed on Mars. The vibrations of rock particles initiate a convection process that caused upper denser and heavier layers of rock to fall and lighter rocks to rise, similar to what happens in your home where warmed less dense air rises above the radiator.  This mechanism drove the flow of deposits up to 40 km away from the mountain source and at phenomenally high speeds.”

The research team includes Apollo 17 astronaut, Professor Harrison Schmitt (University of Wisconsin Madison), who walked on the Moon in December 1972 and completed geologic fieldwork while on the lunar surface.

Professor Schmitt, said: “This work on Martian landslides relates to further understanding of lunar landslides such as the Light Mantle Avalanche I studied in the valley of Taurus-Littrow during Apollo 17 exploration and have continued to examine using images and data collected more recently from lunar orbit. Flow initiation and mechanisms on the Moon may be very different from Mars; however, comparisons often help geologists to understand comparable features".

“As on the Earth, the lunar meteor impact environment has modified the surface features of the Light Mantle Avalanche of the 75+ million years since it occurred. The impact redistribution of materials in the lunar environment has modified features that ultimately may be found to resemble those documented in the Martian landslide study".

“Of additional interest relative to the Light Mantle Avalanche deposit will be the forthcoming examination of a core from the upper 70 cm of the deposit obtained during Apollo 17 exploration. This previously protected core is in the process of being opened and examined by a large consortium of NASA and outside scientists. This important study of a Martian landslide, for the time being at least, has been confined to remotely sensed information.”

The research was funded by the Science and Technology Facilities Council (UK).

Links

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Outreach: Journey to the centre of the Earth – the core of our planet by Prof Lidunka Vočadlo.

This @KnowitWall article takes you beneath the surface of the world you know, and introduces you to Lidunka Vocadlo's (literally) groundbreaking research on the core of the Earth.

Standing on the Earth, you’d probably think it’s made of rock. And you’d be right – mostly. In fact, what you’re standing on is the Earth’s crust. The crust is broken into plates which fit together like a jigsaw, moving around the surface very slowly (a few centimetres a year – like fingernail growth). The thickness of the crust varies, but is generally between 5 and 50 km, so when compared to the size of the Earth, it is very, very thin, like the skin of an apple. Beneath the crust is the mantle – split into three parts – the upper mantle, the transition zone and the lower mantle. This is all solid (apart from very close to the surface where some rock melts) and is mostly silicate rocks, down to about 2900 km. Here, as we reach nearly halfway through the Earth, we hit a big change – to liquid iron (well, actually, an alloy of mostly iron with some nickel and other lighter elements). This is the outer core. At about 5200 km, we reach the inner core – solid iron (frozen by increased pressure, also alloyed with nickel and light elements). The centre is finally reached at around 6400 km.

So why am I telling you all this? Why do we care about the Earth’s core? Well, for a start, the outer core is the source of our magnetic field which protects us from the harmful rays of the sun. Without the magnetic field, our atmosphere would eventually be stripped away by solar winds, and all the water would evaporate –  the Earth would become a completely inhospitable planet. Secondly, the Earth has been cooling from a molten soup, formed about 4.5 billion years ago, to the layered mostly solid structure it is today. Some of the original heat from when the Earth was first formed is still being transported out of the core and mantle. This is the energy source responsible for the dynamics of our planet, leading to surface events, like the mountain building, earthquakes and volcanoes that we observe today.

Now, you must be wondering how on earth we know anything about what is going on more than 6000 km beneath our feet. Did we dig a hole? Well, yes. In fact, the deepest hole that’s ever been dug is on the Kola Peninsula in a remote region of Russia, and it’s just over 12 km deep. Unfortunately, as you dig down, the pressures and temperatures increase so much that by the time you reach around 12 km, all the drill mechanisms start to get mangled. It’s an engineering problem that is currently too expensive to resolve. Another way of getting information about what’s beneath our feet is to look at material ejected from volcanoes. While most volcanoes spew out stuff from just below the surface, there are some particular volcanoes that eject material from more than 200 km deep. That’s deep - but to reach the Earth’s core we still have over 6000 km to go!

graph of cross section of the earth

It turns out that earthquakes, while disastrous for some, are the perfect tool for investigating the deep Earth. Whenever there is an earthquake (and there are thousands every year), energy passes through the Earth in the form of waves. There are two types of wave that travel right through the Earth – a compressional P-wave and a shear S-wave, and these so-called body waves are picked up by seismometers located all over the surface of the Earth. The squiggly pattern drawn out by these seismometers (that you sometimes see in disaster movies) give us lots of information, including the speed at which the waves pass through the Earth. The speed of waves travelling through a material depends critically on the physical properties of that material: specifically, the density, the bulk modulus (how squishy something is) and the shear modulus (how its shape distorts). Scientists can measure or calculate these seismic velocities, and try to match them up with those of materials likely to exist in the Earth. In this way, we can determine what the Earth is made of, when it changes from one material to another, whether it is solid or liquid, and much more. Unfortunately, this is not as straightforward as it may seem, since by the time you reach the centre of the Earth, the pressures and temperatures have increased to over 6000 degrees and 3.5 million times atmospheric pressure. This is equal to the temperature of the surface of the sun and the pressure of 750,000 elephants standing on top of each other (or 700 if they are wearing stilettos!). The technical challenges are immense.

But lots of people have been working on this subject for over a hundred years, and we have made great leaps in our understanding. For example, we know that the Earth’s liquid outer core has been crystallising for around a billion years to form the much younger inner core, and that both are made of iron alloyed with nickel and light elements such as silicon, sulphur and carbon. We know that the outer core is a convecting liquid that is runny like water. We know that in the inner core, waves travel faster pole-to-pole than they do along the equator – suggesting some sort of texture or crystal alignment channelling the waves. We know how iron alloys melt or solidify under pressure, allowing us to determine the temperature at the boundary between the inner and outer core (that’s where we get the 6000 degrees).

Looking forward, the biggest challenge will be getting an exact composition that matches both the seismological observations of the body wave velocities and the density. This is one of the “holy grails” for understanding the centre of the Earth. If we know exactly what the core is made of, we can then work out all sorts of relevant things that have consequences for the entire planet. Research in this area continues and exciting new discoveries about the Earth’s core are on the way. Understanding the material at the centre of our Earth is key to understanding geological events which have shaped Earth’s history.
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Press Release: Ocean ecosystems take two million years to recover after the K/Pgmass extinction.

The Chicxulub bolide impact 66 million years ago drove the near-instantaneous collapse of ocean ecosystems. The loss of diversity at the base of ocean food webs probably triggered extinctions across all trophic levels and disrupted the biogeochemical functions of the ocean.

How long does it take ecosystems to recover from mass extinction and to become functional and resilient again? A team that includes three UCL researchers (Paul Bown, Hojung Kim and Sarah Alvarez) and colleagues from Southampton, Frankfurt and California, have tackled that question by producing an unprecedented record of the biotic recovery that followed after the last mass extinction, 66 million years ago.

ocean ecosystem recovery

In an article published in the journal Nature, they present a 13 million-year record of fossil plankton dynamics in the aftermath of near annihilation, providing a remarkable glimpse into how the marine ecosystem ‘reboots’. The Cretaceous/Paleogene (K/Pg) mass extinction occurred when an asteroid impact caused global environmental devastation and is well known for the extinction of dinosaurs, ammonites and many other groups. But, as well as the loss of these larger animals, there were equally devastating extinctions in the ocean plankton, which removed food production at the base of the marine ecosystem and crippled important ocean functions, such as the delivery of carbon to the deep-sea, which is a critical control on atmospheric carbon dioxide. “We wanted to find out how long the ocean ecosystems took to recover and how this happened”, says Sarah Alvarez (UCL, University of Gibraltar, University of Bristol), lead author of the study. “We looked at the best fossil record of ocean plankton we could find – calcareous nannofossils (they are still around today) – and collected 13 million years of information from a sample every 13 thousand years. We measured abundance, diversity and cell size from over 700,000 fossils, probably the largest fossil dataset ever produced from one site!”

A light microscope image of a plankton community in the mass extinction recovery phase

Figure: A light microscope image of a plankton community in the mass extinction recovery phase, dominated by small cells of one species. Superimposed on this, is a high-resolution scanning electron microscope (SEM) image of the same species. These cells are around 7 microns in diameter (7/1000ths of a millimetre) (images P. Bown).

What did this tell us? Alvarez and co-authors found that these plant-like (photosynthetic) plankton bounced back almost immediately after the mass extinction but that the early communities were highly unstable and cell sizes were unusually small. Major ecosystem disruption persisted for two million years after the mass extinction but the gradual appearance of new species and larger cells helped re-establish a stable and resilient ecosystem. At the same time, carbon delivery to the sea-floor returned to pre-extinction levels, marking the restoration of this critical ocean function. This occurred long before species and ecological diversity fully recovered, as key forms filled essential functional roles. It took 8 million more years for species numbers to fully recover to previous levels.

A take-home message for our current oceans? The marine ecosystem is dependent on the plankton at its base, just as much today as in the past. This study highlights the risks posed by diversity loss which may result in highly unstable communities, loss of important ecosystem functions and long timescales of recovery. “By losing species today we run the risk of removing key players from the ecosystems. What we see in the fossil record is that function is achieved if you have the right players filling key roles. By reducing biodiversity today, we run the risk of losing our critical ecosystem players, whose importance we have yet to fully appreciate” says Paul Bown.

Related Links:

  • Alvarez et al. 2019, Diversity decoupled from ecosystem function and resilience during mass extinction recovery. Nature 2019
  • Prof Paul Bown's research profile
  • “Ocean ecosystems take two million years to recover after mass extinction – new research”  The Conversation.

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The Geological Association (GA)  “Festival of Geology” at UCL

Saturday  2nd November saw the visit of the Geologists Association to UCL for their annual Festival of Geology – an event designed for everyone interested in the Earth and its origins (irrespective of age!). As usual, the North and South Cloisters were teeming with stalls from various local geological societies as well as dealers in minerals and fossils, while the Jeremy Bentham Room (aka the Upper Refectory) became an activities area for children.

Festival of Geology

Many members of our Department - staff, students and alumni - took part in this event. Jeremy Young’s talk on coccolithophores was well received, as were the tours of the Kathleen Lonsdale Building, featuring the Rock Room, our new Teaching Laboratories and the work of several of our research groups. The Greenough Society sold a large number of cakes, and the GeoBus team’s “practicals” on earthquakes and river flow, were very popular with the children, as was the opportunity to make plaster casts of fossils.

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PhD News: Kate Laxton takes part in the Expedition to Ol Doinyo Lengai Volcano, Tanzania.

August 23rd 2019 marks 12 years since Chris Weber [1] collected the last sample of rare natrocarbonatite lava from the then accessible crater floor of Ol Doinyo Lengai, the world's strangest volcanic system [2]. Then, on the 4th September 2007, the mountain unexpectedly exploded resulting in a new >100 m deep pit crater, ending all hopes of further collections. Everyone presumably thought that was that...

Thankfully since the end of the explosive phase of 2007-2008, effusive natrocarbonatite activity has resumed [3]. The crater floor is slowly rising and these scientific gems (aka: future research samples) are inching closer to rim path with only 94 m to go. In time, the crater will refill again and so, we wait...And yet, after a brief visit in 2018, UCL's Earth Sciences PhD student Ms. Kate Laxton (assisted by MSc student Mr. Felix Boschetty) concluded that waiting was no fun. Instead with the support of the Geological Survey of Tanzania (GST) and the University of Dar Es Salaam, a plan was hatched to return in July-August 2019 to retrieve samples that are perhaps only a couple of decades premature.

The plan was simple... stretch a rope across the 300 m wide gaping hole at the summit of the volcano and use a system of pulleys* to send stainless steel cocktail shakers into the open lava lake. Then, using the same rig, send a Multi-component Gas Analyser System (MultiGAS) down to the crater floor to measure volcanic emissions over time. A small number of custom-built CO2 sensors would also be suspended independently of the main line, neatly packaged in glittery hamster balls to help them roll down the inner slopes of the crater. All being well, this would provide a baseline for the current level activity at Ol Doinyo Lengai from which scientists could track changes in the future.

Expedition to Ol Doinyo Lengai Volcano, Tanzania.

The next steps were to secure funding, which was generously provided by the Deep Carbon Observatory [4], and to find a team of level-headed equally ambitious volcanophiles. Recruitment began with Dr. Emma Liu, drone and gas sensing aficionado from the University of Cambridge, swiftly followed by Mr. Arno Van Zyl, Vertica Ltd rope access technician and all round good guy. Three then became nine once our experienced Kilimanjaro guides and local Maasai joined forces to help us pull this off. In the end, one year of planning boiled down to eight windy days and nine cold nights at the summit, the successful collection 6 fresh natrocarbonatite samples, 6 MultiGAS traverses, 2 MultiGAS dips, 3 nights of thermal imaging, 3 drone-based DEMs, 8 tephra samples and a whole load of brilliant teamwork.

All this to say that the first natrocarbonatite lava samples collected since before the explosive eruption of 2007-2008 have safely arrived at Department of Earth Sciences for chemical analysis. The point of which will be to determine whether the composition of said lava has returned to its unusually stable composition (analysed throughout the eruptive phase of 1983-2007) or whether the explosive eruption irrevocably altered the internal structure of the volcano. The answer to this will help us get a handle on the eruption dynamics of this weird and wonderful volcano.

The expedition also offered us an opportunity to demonstrate the value of home-made** budget-friendly gas sensors as a monitoring solution for resource poor institutions such as our collaborators, the GST. These sensors, tested in combination with a MultiGAS from the University of Palermo, allowed us to obtain a time-series for the composition of gases currently emitted in the crater, an important tool for understanding the day-to-day activity of any volcanic system. Our hope is to improve upon our original design and to provide the GST (and others) with the equipment necessary to take ownership of their own monitoring aspirations.

*Courtesy of DMM Wales
**Built with Dr. Kieran Wood (University of Bristol Flight Laboratory).
 

References:

[1] Volcanic Expeditions International (VEI), http://www.v-e-i.de/english/about.html#adr

[2] Keller, J., Klaudius, J., Kervyn, M. et al. Bull Volcanol (2010) 72: 893. https://doi.org/10.1007/s00445-010-0371-x

[3] Global Volcanism Program, 2009. Report on Ol Doinyo Lengai (Tanzania). In: Wunderman, R. (ed.), Bulleting of the Gloval Volcanism Network, 34:2. Smithsonian Institute. https://doi.org/10.5479/si.GVP.BGVN200902-222120.

[4] Deep Carbon Observatory, https://deepcarbon.net/

Related Links

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Alumni News: George Bellas Greenough (1778 – 1855) and The Map that Changed the World.

Although not strictly an alumnus of our Department, George Bellas Greenough FRS FGS, played an important role both in the early development of UCL and in establishing the Geological Society, and so he can be viewed as a founding father of UCL Earth Sciences. Greenough studied at Eton, Cambridge and finally Göttingen, where he developed a deep interest in the natural world. He sat in Parliament for a number of years and, although wealthy, was clearly a man with a social conscience, resigning his commission in the Light Horse Volunteers of London and Westminster after the Peterloo Massacre in 1819. Between 1799 and 1806, Greenough travelled widely throughout the British Isles and Europe and, in 1807, he started a “little talking Geological Club”, which soon evolved into the Geological Society of London; not surprisingly he was elected as its first President. He served the “Geol. Soc.” in this capacity for a total of ten years, being twice re-elected to the Presidency.

In 2001, Greenough suddenly became a controversial figure, following the publication of Simon Winchester’s popular book The Map that Changed the World. Winchester’s thesis was that Greenough, the wealthy “perfumed flaneur”, had done his best to do-down the worthy William Smith, who had published his Delineation of the Strata of England and Wales with part of Scotland in 1815, five years before Greenough’s own Geological Map of England and Wales would appear. However, while this conjecture might have made a good story, it was based on very flimsy evidence. Many of us will remember Eric Robinson’s impassioned defence of Greenough in an impromptu speech that he made at an alumnus dinner shortly after Winchester’s book was published. Perhaps the final words on this subject should be left to Greenough himself, who wrote of Smith “Now my feelings towards that gentleman are directly the reverse. I respect him for the important services he has rendered to geology, and I esteem him for the example of dignity, meekness, modesty, and candour” – hardly the words of an unprincipled opponent. After his death, Greenough bequeathed his papers and collection of geological specimens to UCL and the UCL archives contain copies of his map.

The bust of Greenough in the Rock Room at UCL and Greenough’s Map

Images: The bust of Greenough in the Rock Room at UCL and Greenough’s Map

Next year sees the bicentenary of the publication of Greenough’s map and the History of Geology Group of the Geological Society will be holding a special meeting at UCL in May 2020 in celebration, at which some places should be available for UCL Earth Sciences alumni.

Reference

  • M Kölbl-Ebert (2003) George Bellas Greenough: a lawyer in geologist's clothes. Proc. Geol. Assoc., 114, 247-254.

Greenough Talks and visiting the Department: Any alumni who would like to come back to visit the Department, or who would be willing to speak about their careers to our current students would be very welcome; just Email Ian Wood (ian.wood@ucl.ac.uk) to arrange to come.  

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Resources:

Newsletters:
Spring 2019 | Autumn 2018 | March 2018

Department history
Geology at UCL - A brief history.

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