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Ask Our Experts: Valentin Troll and Juan-Carlos Carracedo

By: , Posted on: August 10, 2016


In our ongoing “Ask an Academic” series, we sit down with Juan Carlos Carracedo and Valentin R. Troll. In this Q&A we discuss their research, work, and publication.

Name: Valentin R. Troll
Title: Chair Professor of Petrology
Affiliation: Uppsala University, Sweden

Name: Juan-Carlos Carracedo
Title: Research Professor CSIC (retired)
Affiliation: Emeritus at the University of Las Palmas de Gran Canaria, Spain

  1. What is your particular area of expertise?

TROLL: In my research I focus on petrology, volcanology and geochemistry to study magmatic processes on a range of scales. This includes, amongst other aspects, the growth of crystals and the information they retain all the way to regional geochemical surveys of magmatic provinces on a hundreds of kilometer scale, such as the Canary Islands or the Indonesian archipelago.

CARRACEDO: Most of my interest has been focused on the study of volcanism, particularly in ocean islands and more specifically in the Canaries. Fortunately, to try and understand how this volcanic archipelago was born and evolved I had to visit other spectacular islands, e.g. Hawaii, Reunion, Guadalupe, Martinique… There I learned from the work of many colleagues and from direct observations and comparisons with my own field of work in the Canaries. I couldn’t be luckier!

  1. How would you explain your current work to a stranger on a bus?

TROLL: In simple terms, my work is assessment of volcanic phenomena, for a number of reasons including hazard assessment, raw materials, and of course also fundamental research. For that, I use field work, chemical analyses of rock, minerals, and gas as well as petrological experiments and modeling to better understand the processes that control volcanism on Earth and other planets.

CARRACEDO: I strongly believe that the main objective of geoscientists  is to work to increase human understanding  of natural processes. But it is equally important to communicate these findings to the general public in a simple and digestible form without losing the necessary scientific rigor (e.g. proposing scientific theories or speculations as facts). Besides admiring the beauty of volcanic forms, structures and landscapes, the general public could undoubtedly benefit from understanding how these features were formed, and this would probably spark their interest and help to increase the relevance of science in everyday life. Our modest effort preparing Elsevier’s  Geology of the Canary Islands is focused in this direction.

  1. Where do you carry out most of your work?

TROLL: Most of my work time is office and laboratory based; where computer work and rock analyses, experiments, and so on are performed. However, I get the chance to see many exciting places when on field work and my focus areas are the Central and North Atlantic regions (including the Canary and Cape Verde Islands, Iceland, the ancient volcanoes in Ireland and Britain)  and the Indonesian archipelago. In addition, I have participated in several cruises aboard scientific research vessels to investigate submarine volcanoes below the Atlantic Ocean and most recently, I joined an expedition organized by the Canadian Geological Survey to the High Arctic where we investigated volcanic rocks for natural resources and to refine models on volcano-climate relationships. I am also a research associate at several Universities and Research Institutes around the globe – for instance at the University of Las Palmas de Gran Canaria, and the Italian National Institute for Geophysics and Volcanology. As you can anticipate, my work involves a lot of travel and can be quite varied!

CARRACEDO: I have also been fortunate in that most of my work has been based in direct observations on the field. Although laboratory and computer time is also essential, my job, as a “generalist” volcanologist, is mostly related to field work. Nothing is comparable with keeping in direct contact with nature, to admire its infinite complexity. Sometimes, with hard work, perseverance and good luck we can get a glimpse of some of its secrets and find explanations to specific questions. Nowadays there is an inclination to practice “virtual geology”, compensating reduced field work with increasingly powerful computer tools. However, as in photography, the final quality depends ultimately on the original pixels. If I have to choose a few particularly exciting moments I would refer to my participation with colleagues of the U.S. Geological Survey in a dive with the Pisces V submersible of the University of Hawaii down to nearly 3000 meters north of the island of Molokai, or attending events such as the 1985  Nevado del Ruiz eruption in Colombia, the  1971 Teneguía eruption in La Palma or the recent 2011 submarine eruption in El Hierro.

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  1. What first inspired you to study Geology/Geoscience?

TROLL: My university career started with physics, which offered the opportunity to take a course in geophysics and geology. While I recall I was skeptical at first, I ended up being fascinated  by how geologists were able to read rocks and mineral associations and wanted to learn all there was to know about this ‘magic ability’. One afternoon, in a practical class, it then happened. The rock handed out to me (an ignimritic rhyolite from Portugal) started to first gently, then more and more clearly answer to my questions, in a language I could suddenly understand, at least in sizeable chunks. And after a lot of careful listening, I grasped the story the rock had to tell. I have not stopped conversing with rocks ever since that magical moment.

CARRACEDO: I  graduated in Geology in 1968 from the University of Madrid because I always liked natural sciences. However I was skeptical because I felt that the most obvious and relevant questions (how mountains, oceans, volcanoes, earthquakes, etc,  formed) were very insufficiently explained, or not at all. Then I sojourned as a postgraduate in Toronto and all my concerns disappeared as I learned the magical theory of plate tectonics that make everything fit. Later, working on my PhD thesis on Tenerife I was invited to attend the Teneguía eruption in La Palma, and since then I was hooked for life on volcanoes.

  1. What’s the most exciting part of your job?

TROLL: The travels are by far the most exciting. I have close colleagues in institutes around the world from Canada to Italy to the Canary Islands to South Africa, and this interaction is very stimulating. However, I must confess that the best of all is seeing a new volcano or indeed a “live” volcanic eruption like at El Hierro in 2011, which is particularly intense. Not much comes close to it.

CARRACEDO: Again, in my field of work nothing is comparable to a volcanic eruption.

  1. What keeps you awake at night?

TROLL: At times my excitement can grow to a state that it is hard to control, such as during very special events, like the El Hierro eruption in 2011. Then it is hard to calm myself down. However, most nights I sleep very well, though I wake usually pretty early.

CARRACEDO: I used to be very worried because of what I perceived as a lack of interest in establishing sufficient means for the prevention of eruptive hazards in the densely populated Canaries (2 million inhabitants and 12 million annual visitors). That may have often kept me awake at night, especially when earthquakes occurred and we had no answers for an anxious public. Fortunately, the Spanish Instituto Geográfico Nacional, which was entrusted with volcanic surveillance in the entire country of Spain, finally became seriously involved since 2004 in the deployment of an appropriate seismic network, that proved highly efficient before and during the eruptive phases of the 2011 submarine eruption in El Hierro. Since then, things that keep me awake some nights are not related to science, but to (bad) politics and their frequently ruthless consequences.

  1. What false preconceptions/stereotypes do people have about your job?

TROLL: Many people think of geologists and geoscientists as outdoor folks with a hammer at the belt and a lumberjack shirt, sitting around campfires after work and consuming large quantities of cool beverages. While these aspects do play a role, they are somewhat romantic, as today’s geoscientists are often very high-tech. We frequently use large and complicated instrumentation to obtain geochemical and geophysical data and the modern geoscientist spends much more time behind a PC or in a laboratory than actually at a camp-fire. Having said this, and probably because of these developments, most of us treasure the rare camp-fire days that are left.

CARRACEDO: Usually I am in the media (TV, newspapers, etc.) in relation to the occurrence of earthquakes or eruptions, either here in the Canaries or anywhere else in the world. These events are typically associated with large numbers of casualties and widespread damage and suffering. We volcanologists and geoscientists in general are very proud of being able to help, not only in these crisis, or providing the information we can, but also through research trying to improve forecasting and surveillance techniques. However, although this is very important, the public is generally unaware, at least here in the Canaries, that this is not the only work we do. We are not just “firefighters”. I am trying to stress this issue in an effort to emphasize the positive side of volcanoes, that not only created these islands, but made them beautiful. People are amazed to learn that almost everything here is related to volcanic processes, not only the landscapes, but also the availability of water resources, the peculiar topography and difficult  communications, the distribution and diversity of climatic zones…and even the existence of the famous golden beaches, that only exist in the islands that were constructed before the Pliocene (before the closure of the Panama isthmus, that drastically changed the existing tropical climate in the Canaries and started the trade winds regime that brings humid and cool weather to the islands).

  1. What’s the most interesting thing you’ve learned this week?

TROLL: Right now I am looking at human responses to volcanic phenomena for one of my projects and I had to make some excursions into human behavior studies and psychology. I learned that over 80% of people would feel an itch in their left leg if asked if they can feel an itch in their left leg. This is on first glance no more than an entertaining fact. On second glance, however, this phenomenon may be a major factor in understanding why some threatened communities refuse to leave altogether while others flee in almost a mass panic. It appears that the different communities have different perceptions of volcanic risks and their internal ways of communication differ from one another. This then implies that no single approach can serve all situations when interacting with populations in volcanic risk areas.

CARRACEDO: The role of giant landslides to favor colonisation of species from one island to another, a fundamental process for the establishment and assembly of island biotas within oceanic archipelagos, that was little understood. A group of biologists at the CSIC in Tenerife invited me to collaborate in this study relating giant lateral collapses and dispersion of fauna, and this is certainly the most interesting thing I learned in the past week and probably for a long time to come.


  1. What do you think will be the next big discovery or development in your field? 

TROLL: Most of us think of volcanoes as a overwhelming force of nature that is so powerful that little can influence or alter its course. However, more and more studies emerge that point at the ‘invisible hand’ behind volcanic phenomena. This may be large tectonic forces that allow magma to ascent in cracks that open, the crustal rock through which magma passes that may add extra volatiles to the magma from volatile-rich country rocks or from groundwater to cause increased explosive behaviour, or that wave action removes the toes of volcanic islands which may encourage large collapses on a volcano’s flank. Such ‘external forcing’ is likely to become a more pronounced aspect in our science over the next decades, because we increasingly learn to isolate processes, causes and consequences, which promises a whole range of new insight to emerge in the coming years.

CARRACEDO: I have no idea, but if I could choose it would be the clear understanding of the behavior of the Earth’s mantle, where all the geological processes seem to ultimately begin.  A lot has been learned in the last several years with seismic tomography, but there is still a long way to go.

  1. How have you used books for your own professional research and how it influenced your work, research or thinking, or help you solve a problem in your field? What outcome did it lead to?

TROLL: Ever since I was a wee lad I enjoyed reading. The world was then not so big, as things started to take shape in my mind, linking the world and myself more closely and making me keen to experience more by reducing my intimidation of those things that seemed too big to grasp at first. Adventure stories gave way to exploration reports and eventually to scientific accounts in form of scientific books and articles. I recall one specific book from my early student days (A. Nicholas’s ‘Structures of Ophiolites and Dynamics of Oceanic Lithosphere’) which sealed my descision to become a geoscientist. Its fundamental points still resonate with me and influence my thinking up to the present day. My ambitions to achieve clarity, overview and properly assess the significance of each aspect goes back to these early student days and the impressions I took from these milestone books, like the one by Nicholas. I hope the new book on the ‘Geology of the Canary Islands’ will display these qualities that I hold so dear and will allow readers to dive deeply into the intricacies of the topic without feeling entirely lost in detail.

CARRACEDO: Books and scientific journals have been fundamental to my professional research, but this is also true in general terms. We cannot imagine a world without documents. With oral communication only we would still be in the dark ages. Writing allows knowledge to accumulate. Then came printing, and books and knowledge became accessible to everyone. Nowadays we have the Internet, and the amount of information is astonishing and is increasing exponentially. Indeed the problem now is to distinguish between correct and erroneous information.

To explore more of their recent work, you can download a FREE CHAPTER (until  10/31) of their book, The Geology of the Canary Islands.

Prof. Troll has worked on the volcanic phenomena of the Canary Islands since the late 1990s and has co-authored some 50 scientific articles on the geology, petrology, and geochemistry of the archipelago. Since 2008, he is an honorary research associate at the Intituto Nazionale di Geofisica e Vulcanologia in Rome, Italy, and since 2012 also at the University of Las Palmas de Gran Canaria. Troll is mainly active as a research professor at Uppsala University, but strongly believes that training young scientists, watching them grow and helping them to capitalise from experienced researchers is vital for securing the future of volcanology and petrology, as well as the future of our society as a whole.

Prof. Carracedo has worked in the Canary Islands for over 40 years and published over 200 scientific articles on the geology, palaeomagnetism and volcanology of the Canary archipelago and authored or co-authored over 20 books and book chapters (in Spanish and English). Although Prof. Carracedo believes that the main role of a scientist is to communicate findings to peers, he is also strongly convinced of the importance of scientific outreach as an essential way to transfer knowledge to the general public, as well as to the next generation of geoscientist working in the archipelago. He hopes to spark interest and wants to help make science relevant to peoples’ every-day lifes.

geology of canary islands

The Geology of the Canary Islands provides a concise overview of the geology and volcanology of the Canary Islands, along with 27 carefully planned day excursions comprising trips on all of the islands. Each stop includes a description on how to approach a site and where to park with GPS locations provided.

Use discount code “STC215” at checkout in the Elsevier Store and save up to 30% on your very own copy!


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