TS
Tectonics and Structural Geology

plate tectonics

Beyond Tectonics: Can only tectonically active planets sustain life?

Beyond Tectonics: Can only tectonically active planets sustain life?

This edition of “Beyond Tectonics” is brought to you by David Waltham. David is a professor of Geophysics at Royal Holloway who studies Geology, Astronomy and Astrobiology. His current research focus is on whether the Earth is “special” because it is habitable, or if the Earth is one of a vast amount of life-bearing planets.

“Is Earth Special? Do we live on a typical rocky world or on one of the oddest planets in the Universe? Are planets capable of harbouring life common across the Cosmos or are our nearest habitable neighbours so far away that we’ll never find them?  We don’t know!”
What does a planet need to be habitable?

This huge question can be broken down into smaller, more specific chunks. Do habitable planets have to have large moons and, if so, how common are they? Do habitable planets have to have magnetic fields and, if so, how common are they? Do habitable planets have to have just the right amount of water and, if so, how common is that?

 

A portion of the Hubble deep field image containing around 3,000 galaxies. image credit: Wikipedia

 

You might think that we’d know the answer to at least some of these more focused queries but we don’t. You can see the review of the current lack of knowledge on these, and other puzzles, here (Waltham 2019). In this edition of Beyond Tectonics, we will be focusing on the question of if habitable planets must have plate tectonics and, if so, how common is that?

 

Plate Tectonics and Habitability

The most obvious way in which plate tectonics might contribute to habitability is its influence on climate or, more specifically, climate stability. Earth’s climate is surprisingly stable. In these times of concern over climate change this probably sounds a little heretical but, when looked at over billions of years, the thing that is most striking, is how little our climate has changed. We’ve had four billion years of “good weather”, in which temperatures never dropped so low that our world froze completely (although, it did get close on a few occasions) or so high that a runaway greenhouse effect set in leading to planet-wide desiccation.

The fossil record shows that biodiversity is massively affected by even quite small temperature changes (e.g. a mere 3% temperature rise probably caused the end Permian mass-extinction (Penn et al., 2018) and so climate stability is an important, and often overlooked, component of habitability. However looking at Earth’s history, and future, the climate should be unstable. Over the 4 billion years life has existed on Earth, the Sun’s luminosity has increased by 30%. Over the same time period, the composition of the atmosphere has altered radically, as has the amount of heat our planet reflects back to space from ice, clouds and the changing continents. Temperatures should have fluctuated by hundreds of degrees, but they did not, which is probably due to plate tectonics.

The big picture here is that Earth has benefited from a coincidence. As the Sun has steadily warmed over the aeons this has been compensated by a drop in greenhouse gas concentrations at just the right rate to keep Earth habitable. Part of the explanation for this is that outgassing of carbon dioxide from the mantle has been dropping as our planet has cooled. Earth’s cooling has only been at the required fast rate because of plate tectonics. Subduction of cold lithosphere into the mantle is a much more efficient cooling mechanism than conduction of heat through a stagnant crust (as happens on every other rocky body in the Solar System) and so our planet cools much more quickly than it otherwise would.

 

The Silicate weathering cycle

Regardless of the change in outgassing rate over time, without the Silicate weathering cycle, CO2 outgassing would cause runaway warming eventually making Earth Venus-like. Carbon dioxide concentration—and hence temperature—of the atmosphere is kept low because of the silicate weathering cycle. Carbon dioxide dissolved in rainfall is slightly acidic and dissolves silicate rocks at the surface to produce, among other things, bicarbonate ions in the water draining to the sea (Raymo and Ruddiman 1992).  These, in turn, precipitate in the oceans to give carbonate sediments and, hence, atmospheric carbon is turned into solid rock thereby removing it from the atmosphere. This process only occurs because plate tectonics continuously replenishes the supply of un-weathered silicate (via mountain building/orogeny, e.g. the Himalaya) and because plate tectonics maintains Earth’s dichotomy of continents and oceans.

These carbonate sediments which build up on the ocean floor are eventually subducted with large volumes of hydrated ocean plate (water ingrained in the chemical structure of the rock). Earth’s interior contains more water than there is on the surface but, without subduction of these water-rich sediments and rocks, all of it would have found its way to the surface by now. If this were the case, then at the very least our planet would be a water-world without dry land. Although, it is more likely that without the silicate weathering cycle and with enhanced atmospheric water vapour levels, our planet would have undergone a Venus-like process of wet, runaway greenhouse warming swiftly followed by desiccation as hydrogen from dissociated water in the upper atmosphere was swiftly lost to space (Kasting 1988).

 

The Himalaya photographed from the International Space Station. Image credit: NASA

 

How important is plate tectonics for planetary habitability?

Plate tectonics should be seen as a prerequisite of planetary habitability. The arguments for plate tectonics being central to habitability are stronger than for almost any other property of our planet. They’re certainly far stronger than those arguments supporting more frequently met suggestions of the centrality of our large moon or of our strong magnetic field (Waltham 2019).

Plate tectonics is therefore important to planetary habitability but is it rare? Our planet is not special in this regard if plate tectonics is common on Earth-sized rocky worlds. Unfortunately, at this time it is not known for certain whether plate tectonics is common or rare. Sophisticated mathematic models of planet-scale convection have not given us a clear answer either. Some of these models suggest that plate tectonics will be common for planets of Earth-size or above but other models show the opposite. Many models, but not all, also suggest that the presence of water in the mantle is key. Other factors that may be important are a low surface temperature (so that the crust is rigid) or the presence of a solid-inner core (heat of fusion provides a significant proportion of Earth’s heat budget).

A different approach to determining plate-tectonic frequency would be to try and detect it on planets orbiting other stars. That’s not as outlandish as it sounds. We already have the technology to analyse the atmospheres of exoplanets and, as indicated earlier, plate tectonics massively influences atmospheric composition. Perhaps there’s a plate tectonic “signature” we can look for in these exo-atmospheres. Exo-tectonics could be a real subject, taught in undergraduate lectures, within a few decades.

References

Kasting, J.F., 1988. Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus. Icarus, 74, 3, 472 – 494. Available at: https://doi.org/10.1016/0019-1035(88)90116-9

Penn, J.L., Deutsch, C., Payne, J.L., Sperling, E.A., 2018. Temperature-dependent hypoxia explains biogeography and severity of end-Permian marine mass extinction. Science, 362. Available at: doi: 10.1126/science.aat1327

Raymo, M.E., Ruddiman, W.F., 1992. Tectonic forcing of late Cenozoic climate. Nature, 359, 6391, 117 – 122. Available at: https://doi.org/10.1038/359117a0DO

Waltham, D., 2019. Is Earth Special? Earth-Science reviews, 192, 445 – 470. Available at: https://doi.org/10.1016/j.earscirev.2019.02.008

Written by David Waltham

Edited by Hannah Davies

Beyond tectonics: The present-day tides are the biggest they have been since the formation of Pangea

Beyond tectonics: The present-day tides are the biggest they have been since the formation of Pangea
“Beyond tectonics” is a blog series which aims to highlight the connections between tectonics and other aspects of the Earth system. In this iteration of the “Beyond tectonics” series we talk about how plate tectonics have affected the tides on Earth over geological timescales. We will talk about tectonics on the Earth since the formation of Pangea to the present day, and into the future, ending with the formation of the next Supercontinent in around 200 – 250 Million years from now.

 

Tides of the Planet Earth

The Earth’s tides are predominantly caused by the gravitational pull of the Moon, and the centripetal force of the Earth due to its rotation. The force of the Moon and the spin of the Earth cause two tidal bulges to form, one that follows the Moon, and one on the opposite side of the planet. These two tidal bulges move around the Earth with a period of 12.5 hours. When the buldge moves over a coast, a high tide occurs, and when a bulge is not over a coast, a low tide occurs. This is why there are two low and high tides each day. These tides vary in strength around the world because ocean and coastal morphology plays a large role in how the tidal energy is distributed.

 

How do tectonic plates affect the tide?

The surface of the Earth is broken up into pieces like the shell of an egg. These pieces, or plates, can be divided into oceanic and continental plate. The main difference between the two types of plate is their buoyancy. Both types of plate are buoyant, however, after it is formed at a mid ocean ridge, ocean plate becomes less and less buoyant with age. Eventually, after around 30 million years, ocean plate is less buoyant than the underlying mantle meaning it could sink if it reached a subduction zone. In the present-day oceans, almost all plate older than 180 million years old has sank back into the mantle at a subduction zone. This recycling of ocean crust is what causes the oceans to change shape. The continents are pulled together by the closing oceans (sinking ocean plate), and pushed apart by the opening ones (creation of ocean plate). In the present day, the Pacific is closing and the Atlantic is opening, causing the plate drift map to look like this:

The major subduction zones on Earth. Black arrows illustrate trench migration vectors, while open arrows illustrate plate velocity (credit – Schellart et al., 2007)

As the oceans grow and shrink, their width changes. This means the tidal wave in those oceans has either too little, too much, or just the right amount of space to flow in the ocean. In the present-day the Pacific is too big, the Indian ocean too small, but the Atlantic ocean is just the right size to make the tide resonant.

 

What is resonance?

To explain resonance, imagine the tidal wave moving across the Atlantic ocean and back, like a child on a swing. If you apply the force on the swing when it is at the highest point, you are applying a force at one of the natural frequencies of the system, so the energy you input will make the swing go higher. If you push the swing before or after it reaches its peak, then you might input some energy, but it won’t be as efficient. The Atlantic ocean is just the right width to allow the wave to “swing” back and forth. The input of energy is applied at just the right point, one of the natural frequencies of the tide, to allow resonance.

It is possible for this to happen in any ocean basin. An ocean basin can house resonant tides when the width of the basin (L) is equal to a multiple of half wavelengths of the tide  (𝜆 = √gHT),  where (T) is the tidal period, (g) is gravity, and (H) is water depth. Essentially, when the ocean basin has a width that intersects with a natural frequency of the tide, it will become resonant.

 

The Super-tidal cycle

The reason why the present day tides are the biggest since the formation of Pangea is because the Atlantic is currently resonant with the tide, i.e. it is in a Super-tidal period. Looking at the energy of the tides from when Pangea existed to the present-day (Green et al., 2017), we can see that during Pangea’s life the tides were weak. That status quo continued from 180 to 1 million years ago, when the Atlantic suddenly developed large tides. The Atlantic had been growing all that time, and had finally reached a width where the tide became resonant.

M2 tidal amplitudes since the breakup of Pangea (credit – Green et al., 2017)

The large present-day Atlantic tide is unlikely to last. Green et al., (2018) predict that this super-tidal period will last around 20 million years, and Davies et al., (2019) predict another won’t occur for tens of millions of years, depending on how the future Earth develops.

Therefore, what are the implications of the present-day Atlantic having such large tides? Further testing of the implications of the Super-tidal cycle is needed before any conclusions can be made on how it may affect the Earth system. However, the larger energy input into the oceans during a Super-tidal period may enhance tidal mixing, which means the ocean will have a better distribution of nutrients and oxygen, i.e. it is less likely for it to become stratified. What we do know right now, is that Supercontinents generally have very weak tides (Green et al., 2018), and periods of continent divergence similar to the present day, have larger, or sometimes Super-tides (Balbus 2014; Davies et al., 2019).

 

References

  • Balbus, S. A. 2014, Dynamical, biological and anthropic consequences of equal lunar and solar angular radii. Proc. R. Soc. A, 470. Available at: http://doi.org/10.1098/rspa.2014.0263
  • Davies, H. S., Green, J. A. M., Duarte, J. C., 2018, Back to the future: testing different scenarios for the next supercontinent gathering. Global and planetary change, 169, 133 – 144. Available at: https://doi.org/10.1016/j.gloplacha.2018.07.015
  • Davies, H. S., Green, J. A. M., Duarte, J. C., 2019. Back to the future 2: Tidal modelling of four potential scenarios for the next Supercontinent gathering. Presented at EGU 2019. Available at: https://meetingorganizer.copernicus.org/EGU2019/EGU2019-1004-1.pdf
  • Green, J.A.M., Molloy, J.L., Davies, H.S., Duarte, J.C., 2018. Is there a tectonically driven super-tidal cycle? Geophys. Res. Lett. 45 (8). Available at: https://doi.org/10.1002/2017GL076695.
  • Schellart, W.P., Freeman, J., Stegman, D.R., Moresi, L., May, D. 2007. Evolution and diversity of subduction zones controlled by slab width. Letters to Nature, 446, 308 – 311. Available at: doi:10.1038/nature05615

Meeting Plate Tectonics – Barbara Romanowicz

Meeting Plate Tectonics – Barbara Romanowicz

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie!


Meeting Barbara Romanowicz


Barbara Romanowicz studied mathematics and applied physics and did two PhDs, one in astronomy from Pierre and Marie Curie University and one in geophysics from Paris Diderot University. After her postdoctoral studies at the Massachusetts Institute of Technology, she researched at the Centre national de la Recherche Scientifique (CNRS), where she developed a global network of seismic stations known as GEOSCOPE to study earthquakes and the interior structure of the earth. She currently splits her time between a professorship at UC Berkeley, California, where she does research, and a teaching position as the Chair in Physics of the Earth’s interior at Collège de France, in Paris, where she teaches to the public.

I go between theory and observations, back and forth.

What is your main research interest and which approach do you use in your research?

Barbara Romanowicz in class. Credit: Barbara Romanowicz

My main research interest is the Earth’s interior: figuring out the dynamics and the evolution of the Earth by providing constraints from seismic imaging at the global and continental scale, from the lithosphere to the inner core of the Earth. The methodology that we use is primarily tomography. In my team, we develop new techniques in tomography, so we can achieve higher resolution. But also other types of seismic waveform modelling.

What would you say is the favorite aspect of your research?

What I find most exciting is that I go between theory and observations, back and forth. This brings different types of excitements. For example, developing a method that works is exciting, and so is finding something new in the data. Making progress and discovering something new, basically through a lot of attempts at modelling, and commonly after a lot of time, is very rewarding.

If we do not contribute to it, we will not have any more data.

Why is your research relevant? What are the possible real world applications?

The research is relevant because we are trying to understand the driving mechanisms of plate tectonics. And plate tectonics is what causes earthquakes, volcanoes, tsunamis, and all other natural disasters related to the solid Earth. It is not directly relevant, of course, because of the different timescales; the dynamics of the interior of the Earth are in millions of years, and people are interested in timescales of decades, maybe hundreds of years. So this is a bit of a challenge, but if we do not understand the causes of natural disasters, it is not possible to mitigate them.

Depth cross-sections through model SEMUCB_WM1 (French and Romanowicz, Nature – 2015, doi:https://doi.org/10.1038/nature14876) highlighting broad low velocity “plume-like” conduits beneath major hotspot volcanoes in the central Pacific.

What do you consider to be your biggest academic achievement?

I was asked this question recently, and I did not hesitate to say that I was able to make some impact with my research, but also to contribute to the infrastructure of research. I have been involved since very early in my career, in the development of seismic networks at a global and later regional scale, or trying to put stations in the oceans… Developing the infrastructure to collect data for research is a very recurrent issue that people should keep in mind: if we do not contribute to it, we will not have any more data. If the younger generation of researchers keeps on considering that the data is granted, and do not take up this challenge, the good situation that we’re at will not last.

I thought it is kind of cool that we could show that.

What would you say is the main problem that you solved during your most recent project?

In a fairly recent project, we were able to not only to confirm that there is an ultra slow velocity zone at the base of the Iceland plume near the core-mantle boundary, but also to determine that it is circular in shape. This required being able to illuminate it from different sides, and showing that the same model works for whichever way you look at it. I think that the fact that we can show that is kind of cool, as it combined modelling of seismic waveforms, as well as some imagination in 3D geometry.

Seasonal changes in the dominant locations of the sources of the earth’s low frequency “hum” (top) as inferred from seismic data, compared to the distribution of significant ocean wave height (bottom).

We are not doing enough to raise funds [to build a seismic network infrastructure].

What would you change to improve how science in your field is done?

In my field, which is global seismology, we really rely on a large network of stations, and we need a lot of instruments. Ideally, we would like to cover the entire Earth with instruments, which is not only logistically difficult but also very expensive. I think we are not doing enough to raise funds to build this better infrastructure. The astronomical community, for example, develop decadal plans to build the next generation instruments. In a way, it is easier for them because they need perhaps only a small number of telescopes, whereas our systems are completely distributed, so it is harder for us to join forces. Nevertheless, we are not doing enough of that.

3D rendering of a portion of upper mantle shear velocity model SEMum2 (French, Lekic and Romanowicz, 2013 – Science, doi:10.1126/science.1241514) showing interaction of mantle plume conduits with the asthenosphere beneath the south Pacific superswell (A) and the presence of quasi-periodic low velocity “fingers” aligned in the direction of absolute plate motion extending below the oceanic low velocity zone (B).

What do you think are the biggest challenges right now in your field?

There are several computational challenges, in the sense that we are moving increasingly towards modelling the complete seismic wavefield using numerical methods that are computationally very expensive. One has to think about how big the computer is that you can use, and balance that by finding smart ways to speed up computations in a way that doesn’t rely too much on big computers.

Another really big challenge is to reach the ocean floor and to cover the oceans with broadband seismic observatories. We don’t have enough such stations, and two-thirds of the Earth is covered by oceans. We have less resolution in the southern hemisphere and in the middle of the ocean just because we do not have enough seismic stations on the ocean floor. This is a problem for research on ocean basin structure and deeper upper mantle structure beneath the oceans, but also for research on the very deep Earth, including the inner core. Ocean Bottom Seismometers are great, but we really need very broadband recording, with good coupling to the ground and for long enough times (several years), as well as really large aperture arrays to be able to catch seismic waves over a large azimuth and depth range.

I never really worried about my career.

Barbara Romanowicz. Credit: Barbara Romanowicz

When you were in the early stages of our career, what were your expectations? Did you always see yourself staying in academia?

I think times have changed a lot. When I was doing my Ph.D., I really didn’t have any expectations. I never worried about my career. I simply did not think about it. Probably because I was naive, but also because there was less of a concern at that time… maybe it was easier to find jobs. The landscape was quite different.

Primarily thinking about their [ECS] research will get them where they want to be.

What is the best advice you ever received?

I think the best advice I received is to be daring, to think broadly and about the big picture. So, my best advice to Earth Career Scientists (ECSs) is the same. I would recommend ECSs not to worry too much about their immediate results or about their citation index, but to really think about their research. Primarily thinking about their research will lead them where they want to be. Otherwise, their thinking can be polluted by practical worries. Also, you will always get into situations where you cannot do all the work that you need to do for your research because you have other demands on your time. So my other advice to ECSs is to always keep a couple of hours (the best ones) during the day to completely isolate yourself and work on your research. It is very important. Everything else is easier, but the research itself is the hardest, and if you get distracted you will end up frustrated by not being able to accomplish much.

 

Barbara Romanowicz. Credit: Barbara Romanowicz

 

Interview conducted by David Fernández-Blanco

Meeting Plate Tectonics – Jean-Philippe Avouac

Meeting Plate Tectonics – Jean-Philippe Avouac

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie!


Meeting Jean-Philippe Avouac


Prof. Jean-Philippe Avouac initially studied mathematics and physics during his undergraduate and graduate degrees. Later he got more inclined towards geophysics and then he discovered Earth Sciences. During his Ph.D. at the Institut de Physique du Globe de Paris, advised by Paul Tapponnier, he immersed himself in geology and tectonic geomorphology. Currently, Jean-Philippe Avouac is a Professor of Geology at the California Institute of Technology.

Like living organisms, earthquakes have a life cycle: they nucleate, grow and arrest. There can be some lineage but each earthquake is a different being.

Fieldwork along the Kali Gandaki (Nepal) in 1999. Credit: Barbara Avouac

Where lies your main research interest?

I study crustal dynamics: How the crust is deforming as a result of earthquakes, but also as a result of viscous processes. I study the process of stress accumulation on faults, the release of this stress by earthquakes, as well as how earthquakes and other mechanisms of deformation are contributing to building the topography and geological structures in the long run.

 

How would you describe your approach and methodology?

In my group, we develop techniques to measure crustal deformation using in particular remote sensing and seismology. We were using radar images initially, and we have moved toward using more optical images with time and also GPS data… We try to reproduce the observations (geodetic deformation, kinematic models of seismic ruptures, gravity field…) using dynamic models to determine what are the forces and rheologies needed.

 

What would you say is the favorite aspect of your research?

What I like most about my research is mentoring Ph.D. students and postdocs. I love matching their skills with good problems, problems that will be attractive to them and that will resonate with the currently hot questions in Earth Sciences. I really love doing that.

The other thing I love is to use what I learned as I student (maths and physics) to answer science questions arising from natural observations. I love that part when you look at nature, you observe something and try to measure it quantitatively and then you try to explain the observation with dynamic models. I really enjoy going back and forth between observations and modelling. And the field! I really like being in the field… This is an aspect of the job that really attracted me initially.

We built from what other researchers had done before, but we reached quite different conclusions […] that’s exciting!

Jean-Phillipe Avouac leading a field excursion in the Dzungar basin, 2006. Credit: Aurelia Hubert-Ferrari

 

Why is your research relevant? What are the possible real-world applications?

A significant fraction of my research is relevant to seismic hazards. After my Ph.D., I worked for the Commissariat à l’Energie Atomique (CEA) for 10 years. I was conducting seismic hazard assessment studies for nuclear facilities. So, I have been exposed to the applied side of earthquake science and I like that some of the research we do in my group can help to improve the way we do seismic hazard assessments.

But what I really want to say is that I do not think relevance should drive academic research. In that regard, I should say that I don’t like much the way the funding system works today. I think there is too much emphasis on relevance to society. The idea that you start from stating problems of societal relevance, and only then see what kind of research we can do to solve this problem is not a good approach, in my opinion. I don’t think this is the way important scientific discoveries are made. You make discoveries by being curious, by observing nature with an open mind, by exploring new ideas and coming up with new concepts, or by observing something that is not explained in the current theoretical framework that we have and then you make use of the knowledge that you build after looking at these problems. There is no way you can clearly anticipate where the joyful exploration of an intriguing idea or observation can lead but we know from experience that the society benefits from curious scientific exploration. So, although I think there is relevance in what I am doing, I do not think that, in general, relevance to society should be driving academic research.

 

An outcome of Jean-Phillipe Ph.D Thesis, later published in Kinematic model of active deformation in Central Asia (Avouac and Tapponnier, GRL – 1993; doi: https://doi.org/10.1029/93GL00128).

I do not think relevance to society should drive academic research

What would you say is the main problem that you solved during your most recent project?

People in my group work on many different projects that are all very exciting to me. I’m going to mention just one project though because I can not possibly list them all.

We have done a lot of work in the past to develop techniques to invert geodetic measurements for fault slip at depth. A postdoc and a graduate students in my group have moved on to improve the technique and use it to document slow slip events in Cascadia over the last 15 years. That was a daunting work but their hard work and perseverance have really paid back. The end result is amazing! We see how the slow slip event initiate, propagate, arrest, trigger one another… We built from what other researchers had done before us, but we reached quite different conclusions given that we now have a more complete view of the behaviour of the system –that’s exciting! I anticipate that we are going to learn a lot about the dynamics of slow-slip events, and maybe it will have important implications for regular earthquakes!

What do you consider to be your biggest academic achievement?

The research for which my group is probably best known is that we have done in the Himalaya. In particular, we have built a model of the seismic cycle that explains the observations that we have from seismology, geodesy, geomorphology and geology. We worked a lot on the Himalaya, in part because I love mountains, but also because it is a very unique setting to study orogenic processes which are still active today. There is really no better place where you can get geological constraints on the thermal and structural evolution of the range. There is a lot of erosion and it has been going on for a long time, so the rocks that have been brought to the surface have recorded the thermal and deformation history over tens of million years. Our research has helped understand how the Himalaya has formed as a result of seismic and aseismic deformation, and I think it has yielded important insight on orogenic processes and the seismic cycle in general.

By the way, I don’t mean that earthquakes are periodic. Like living organisms, earthquakes have a life cycle: they nucleate, grow and arrest. There can be some lineage but each earthquake is a different being.

Animation showing the process of stress build up and release associated to earthquakes along the Main Himalayan Thrust fault, along which India is thrust beneath the Himalaya and Tibet. Credit: Jean-Philippe Avouac, Tim Pyle and Kristel Chanard.

We tend to build walls between disciplines […] We would not have been able to discover plate tectonics without a deep cross-disciplinary dialogue

What do you think are the biggest challenges right now in your field?

As I mentioned before, the funding system is an issue. Funding agencies are clearly making a big mistake in prioritizing social relevance as a criterion to evaluate proposals. Aside from that, the challenge that we have in the Earth Sciences is that we tend to build walls between disciplines. Specialization is a natural drift, and you can make a very successful career in a particular field pushing further a particular analytical or modelling technique. Also, it is easier to get funding for what you are known to be good at. As a result, walls between disciplines are building with time. The vocabulary is evolving in each individual discipline and it is increasingly difficult to make major advancements that can bridge different disciplines. In my research, I try to navigate from one discipline to the other… but it is a challenge –while it can be key to make significant discoveries, it takes time and effort. There are fewer and fewer people making a carrier this way. It can be dangerous because of a dilution effect, but at some point, it is needed. Look at plate tectonics for example: it happened because of advances in different disciplines but most importantly because some scientists were aware of these advances and were able to connect them and derive a coherent global framework. We would not have been able to discover plate tectonics without a deep cross-disciplinary dialogue.

Another challenge is that nowadays we have a lot more data than we used to have. This is both an opportunity and a threat. There is a trend to produce more and more publications, that look very solid because they use a lot of data, but that are in fact very incremental. More of the same is not necessarily advancing knowledge at a fundamental level. We have to be imaginative with regard to how to process the increasing flux of data, but it should not come at the cost of being imaginative with regard to what they mean.

I do not like the way the funding system works today

When you were in the early stages of our career, what were your expectations? Did you always see yourself staying in academia?

After my Ph.D. I did not stay in academia. But even when outside academia, I kept doing research, because I had an appetite for it and was working in an environment where scientific curiosity was valued, even if science was not the main objective. Although I was not unhappy at all outside academia, I decided to go back to it since I found it more exciting for myself: I like to solve scientific questions but there is not so much I could solve without the help of students and postdocs. I didn’t consider staying in academia after my PhD because there were sides of the academic life I did not feel comfortable with… I was finding people in academia to be a bit… difficult sometimes, with big egos and not so open minded. Also, we are a very conservative community. There’s a reason for that, for we as scientists have to be sceptical and to push back new ideas and new observations. I guess I have now become now one of those crazy and conservative academic guys (laughs)!

 

Mapping and sampling Holocene terraces abandoned by rapid climate-driven incision in the Tianshan. Credit: Luca Malatesta

If you have a new idea… you will probably have a hard time

What advice would you like to share with Early Career Students?

My first advice is to be aware of the important questions that we should try to solve. Not because they are relevant but because they are interesting and because they are timely, given the tools and data that we have access to. Being aware of the really big questions is important because we tend to forget them sometimes as we become more specialized. And be also aware of the new techniques available, especially those that you could draw from other fields; computer science or medical imagery for example… It is important to be curious and see what is happening in other fields so that you can transfer new ideas and new techniques to your own field and give a try at answering big science questions.

Be curious, be adventurous. Take risks. Try things that might not work. You might be losing your time but it is also an opportunity to make real fundamental advancements. You can make a career by increments, but I think it is not as rewarding as taking risks and really solving a difficult problem.

Follow your own dreams and don’t be intimidated by peer pressure. If you put a new idea on the table, a really new one, first, you will probably have a hard time expressing it clearly… And second, peers will most probably push back, as they should. So do not be intimidated, believe in your ideas, and keep adjusting and pushing them forward. I see too many times students or postdocs who meltdown and get discouraged if they receive a negative comment after a presentation… – I would say, that could, in fact, be a good sign! You may be doing something different and maybe people are not understanding because there is something disturbing and really new!

 

Jean-Phillipe Avouac. Credit: Trish Reda.

 

Interview conducted by David Fernández-Blanco

Meeting Plate Tectonics – Nicolas Coltice

Meeting Plate Tectonics – Nicolas Coltice

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie!


Meeting Nicolas Coltice


Nicolas Coltice graduated with a PhD from the École Normale Supérieure of Lyon, France. He then became assistant professor at the Université Claude Bernard in Lyon, and ultimately, full professor. As of last year, he also holds a professorship position at ENS Paris, France. He has received an ERC grant for the project AUGURY and he is one of the co-founders of the manifesto ’Did this really happen?’, which addresses sexual harassment and inequality issues within sciences.

 

Nicolas Coltice. Credit: Eric Le Roux / Université Claude Bernard Lyon 1.

I think it is extremely important that models are supported by evidence or data.

Hi Nicolas, could you tell us about your research interests and the methods you use to solve your problems?

Sure! My research interest is focussed on mantle convection and geochemistry. The research I do is strongly directed to combine models and observations to understand, for example, the geochemical cycle. I also combine observations and inverse models to build tectonic reconstructions and 3D spherical models. I work a bit with geologists and so I sometimes go into the field. I think it is extremely important that models are supported by evidence (or data) and so I try to combine this as much as I can in my research.

You have been active on different topics. What achievement in your carer are you most proud of?

The one thing I’m most proud of is setting up an ERC team for the project ‘AUGURY’, which happened to have more women than men, which is quite rare in our field. I feel we made quite some progress on undermining the patriarchy within sciences with this ERC project. I’m very proud to work with my team. One of the good things that came out of ‘AUGURY’ is our manifesto ’Did this really happen?’. It is a website where we tell the stories on sexual harassment and gender inequality that women in sciences using comics. Besides advocating gender equality science I also teach, which I find very fulfilling and my teaching is well-received.

Good research needs time.

Did this really happen?. Courtesy of www.didthisreallyhappen.net.

It’s fantastic that you are making the community aware of these more social issues. In terms of research, how does that benefit society?

The application of my research to society is first of all doing the job by itself. Every day that scientists invest in understanding parts of our planet is beneficial to society, just by the very act of it. Publishing my work might give a breach to society and offer perspectives that were not thought of before. I guess a more concrete way my research benefits society would be in the reserve or resources industry, where we always like to understand better where resources form and why they form under certain condition. This will eventually help to actually find them and exploit them and the better we understand that, the less impact it will eventually have on the environment.

Every day that scientists invest in understanding parts of our planet is beneficial to society, just by the very act of it.

 

How do you see the future in geoscience?

In my opinion, good research needs time. Currently we are given very little time to do good research. If we want to change the publishing-focussed mentality, we need to start at the bottom. We do not necessarily have to create a big revolution, but from the inside we can collaborate and slowly change the system. For example, if you publish, public money is used to pay for your publication. This public money then often goes to stakeholders, which is not good! We can change this by publishing in different journals with different ethics. This way, we can slowly lower the pressure we feel on publishing nowadays. So in terms of future, I think we need to get back to the core, do good research.

Selected 3-D view state of the model. Continental material is highlighted in yellow. Figure from Coltice & Shephard, 2018 “Tectonic predictions with mantle convection models”, Geophysical Journal International, 10.1093/gji/ggx531.

When you feel it gets rough, stick with your plan and keep your relationship with your colleagues positive.

One last question, what advice would you like to give to Early Career Scientists?

When I was hired 15 years ago, times were different. If recruiters had the choice, they would always go for the youngest person, not necessarily the best. Nowadays productivity is the factor that counts most and is imposed on people which makes it very difficult to maintain an interesting profile at an early stage in your career. I would advise to find time and space to feel good and let go of the pressure you might feel in your work. I believe there is room for everyone, just keep the spirit up. When you feel it gets rough, stick with your plan and keep your relationship with your colleagues positive.

Nicolas Coltice. Credit: Nicolas Coltice.

 

Interview conducted by Anouk Beniest

Meeting Plate Tectonics – Francis Albarède

Meeting Plate Tectonics – Francis Albarède

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie!


Meeting Francis Albarède


Francis Albarède started his career as an undergraduate student in Natural Sciences at the University of Montpellier in southern France. He moved to Paris to get a PhD in Geochemistry, supervised by Claude Allegre, at the Institut de Physique de Globe de Paris (IPGP). After his PhD he remained at IPGP as researcher and teacher. He then moved to Caltech, where he stayed for two years. The National School of Geology in Nancy, France, offered him a professorship, a position he happily fulfilled for 12 years. In 1991 he switched to the Ecole Normale Superieure in Lyon, France where he holds a director position of the department of earth and life sciences until today.

 

Hi Francis, could you briefly introduce your research interests and methods?

Francis Albarède. Credit: Francis Albarède.

Sure. I’m a geochemist, and I apply geochemistry to understand mantle dynamics and the evolution of the mantle. I also use geochemistry to investigate other planets and work on ocean dynamics. Besides geochemistry, I also use isotopes and trace elements to understand the mantle dynamics and I use models to predict the complexness of magmatic and oceanic processes. Besides earth scientific questions, my methods can be used in archaeological problems or medical issues. My interests are mainly within the field of earth sciences, but I sometimes venture to different fields of research.

Interdisciplinary research needs to be enhanced.

You have quite an extensive career. What do you consider your biggest accomplishment in your field?

The introduction of geochemical modelling I consider one my most significant achievements. And of course, the introduction of the MC-ICP Mass Spectrometry in the mid-’90s within geosciences had tremendous success. At the time it was a new technique and it has become one of the most dominant geochemical tools in many different laboratories around the world. In geodynamics, the idea that continents grow from the head of superplumes was also successful.

Besides these big accomplishment, do you have personal projects too?

Yes, I do have a couple fun projects of my own. They often have to do with introducing new data. For example, I am currently working on using a panel of isotopes (silver, lead, copper) to understand the origin of money.

Science is actually quite hard work.

You have seen many changes in your field. What do you consider one of the biggest challenges in your field nowadays?

Interdisciplinary research needs to be enhanced. The geochemists are good at their own job, and so are the geophysicists. But we need more people that are knowledgeable in both geochemistry and geophysics, a gap that is difficult to bridge. In addition, few scientists ask the right questions. Always ask yourself why other people should care about your own research.

A two-stage history of He in the marble-cake mantle made of fertile (e.g., U- and Th-rich “pyroxenite” in beige) and refractory (e.g., U- and Th-poor “dunite” in green) rocks. Francis Albarède, 2008. Rogue Mantle Helium and Neon, Science, Vol. 319, Issue 5865, pp. 943-945, DOI: 10.1126/science.1150060

 

When you were at the early stages of your career, what were your expectations?

I never expected to be successful at an international level, but it happened anyway. I was craving to make great discoveries, and, even though the road to it was very bumpy, it happened, at least to the best of my capacities.

The most important is to think out of the box.

What is the most valuable advice you have received in your career?

As an early career scientist, I was very arrogant, even more than today. I received the advice, mainly from foreigners, to be more rigorous or demanding to myself. I was told that science is not just a quick effort, or that you do not get important results with a snap of your fingers. It is actually quite hard work. Claude Allegre, my PhD supervisor predicted I would always be a student and sure enough, I still am a student. I am not sure if I became less arrogant, but I definitely took his advice to work harder and to become more rigorous.

So, as the last question, do you have any advice for Early Career Scientists that are aiming for a career in science?

An Early Career Scientist needs to be exposed to other groups and individuals, preferably those who think differently. Perk is the great strength of being young but the danger is to reinvent the wheel. Do not think that something understood 50 years ago is necessarily obsolete. The most important is to think out of the box. This is not an easy thing to do, but if you manage it will make you a different scientist and therefore much more valuable to the community. Being scholarly will multiply and enlarge your sources of information. Read a lot, cultivate your memory, and most of all, have faith in your own capacities.

 

Francis Albarède. Credit: Société Française d’Exobiologie.

Interview conducted by Anouk Beniest

Meeting Plate Tectonics – Eric Calais

Meeting Plate Tectonics – Eric Calais

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie!


Meeting Eric Calais


Eric Calais is Professor of Geophysics and Head of the Geosciences department at the Ecole Normale Supérieure in Paris, France. He was a postdoctoral researcher at Scripps Institution of Oceanography, then became a professor of geophysics at Purdue University (USA) where he remained for 12 years. He is renowned for his work on the kinematics and dynamics of active tectonic processes in Asia, Africa, and the Caribbean. Further, Prof. Calais is highly interested in geo-communication. He has served multiple times as expert-consultant in seismic hazard and risk reduction and was a scientific advisor to the United Nations in Haiti from 2010 to 2012.

We tend to be academics and nothing else, that is not sufficient

Where lies currently your main research interest?
My main goal is to understand the present day deformation of the Earth crust, but not only at tectonic plate boundaries, also in plate interiors.

Eric Calais standing next to a GPS antenna at the Cherry Lane meteorological station of Purdue University. Credit: Purdue University

We have known for 50 years about Plate Tectonics. We know how to describe the motion of plates at the surface of our planet and we know that this has been going on for hundreds of millions of years. There are two questions I am interested in:  What drives these motions? What is the engine? The second one is focused on the idea that the earthquake’s energy is released at plate boundaries, so they are linked to plate tectonics, but we really haven’t said much about why earthquakes occur. What is the mechanic of earthquake faulting? How is that driven by friction, stress, fluids? We are perhaps close to a significant transition in our understanding of earthquakes.

For part of my research, I look at the earthquake process from an angle that is different from that of most of my colleagues, who work in areas where there are a lot of earthquakes. I am interested in areas that are not deforming very rapidly or not at all, the internal parts of tectonic plates, but that do produce earthquakes from time to time. Sometimes very large ones. I try to understand why earthquakes occur within plate interiors and what does it mean in general. Of course, that could be then applied to any kind of earthquake.

What would you say is the favourite aspect of your research?

Fieldwork. That’s the reason why I went to Earth science instead of biology. Because I had the opportunity to be outside, not being confined to the lab. Another one is lectures with students and postdocs, with younger people. The older I grow, the more important the connection with them becomes. There is this notion that the younger generation is never as good as the previous one, I think this is wrong. They are as good, and probably much better than we were. I always learn from my students and PostDocs. Having the blessing of interacting with them, is something that is very important to me.

It’s really hard to make big changes in the real world as a scientist and influence some of the decisions […]

Why is your research relevant? What are the possible real world applications?

The real world applications of my research are twofold.

Calais & Minster (1995). GPS detection of ionospheric perturbations following the January 17, 1994, Northridge Earthquake. Geophysical Research Letters, 22(9), 1045–1048.

People like me who try to understand why earthquakes happen make measurements, calculations and models. Thanks to this we are able, not to make predictions, but to make assessments about how big the next earthquake may be. And this is already an important step towards earthquake safety. Because if you know what to expect you can integrate that information in seismic hazard models, then an engineer or an architect will be able to use this information to design earthquake-safe buildings. There is a strong link between the observations in the field, the measurements and the calculations we make, and the applications for earthquake safety.

The second aspect is communication with the broader public and with decision makers. It’s awareness raising amongst the population as a whole and also amongst the decision makers. That is the most difficult part of the job, really. The first part, converting measurements into something an engineer can use to better design a building, that’s the “easy” part, it’s doable and it is tractable, it is something that is very tangible for scientists and engineers.

The second one is much more difficult and it requires a lot of energy and you never know whether or not you succeed in making a point, in influencing decisions. Nevertheless, I think that scientists, as a whole, and in particular scientists working on earthquakes, have to step outside of their comfort zone. We tend to be academics and nothing else, that is not sufficient. We need to go out and speak about what we know and speak at the proper level to raise awareness amongst the population.

 

What do you consider to be your biggest academic achievement?

Post-2010 earthquake measurements in Haiti – Credit: Ecole Normale Supérieure, Eric Calais

It’s hard to tell… I think that we have been able to change the way one thinks about earthquakes within plate interiors over the past years. It’s hard to talk about achievement at this point but I would say there is a trend. If that trend continues, I have high hopes that it will lead us to a better understanding of why earthquakes occur, not only within plate interiors. Many people might not be interested, or they might not even be aware that there are significant earthquakes in plate interiors.

In France, we care a lot about that because 70% of the energy we use comes from nuclear power and we want those nuclear power plants to be earthquake safe. So what is the potential of an earthquake hitting one of those in France or Germany or anywhere in the world is a multibillion-dollar question. It is very interesting to study the earthquake process within plate interiors where you do not have to worry about plate motions or complications, the system is quite simple. I think it’s a system that is more tractable than the plate boundary system, which is more complicated. Trying to make progress in understanding this particular type of earthquakes is something I am pushing hard for right now in my research, with colleagues, PhD students and postdocs. I think that if we understand them better, we will have progressed towards understanding earthquakes as a whole.

Again, I’m not sure this is an achievement, but I am happy I worked with the Haitian Government under the United Nations as a scientific advisor after the earthquake in 2010 in Haiti. The earthquake was not that big, magnitude 7.1, but it had a large impact on the population and the economy. I am happy that I was able to step in and trigger some small changes. It’s really hard to make big changes in the real world as a scientist and influence some of the decisions that were made during the reconstruction that followed the earthquake. In a way, this was an achievement, but again very hard to measure quantitatively.

Do we ever solve problems or do we discover more problems?

What would you say is the main problem that you solved during your most recent project?

Do we ever solve problems or do we discover more problems? (laughs) I think the problems that I’ve solved are easy problems. I would take two recent examples:

Installation of a GPS measurement site in Haiti after the 2010 earthquake. Credit: Eric Calais

One of the problems we were facing a few years ago, was whether there is or not an accumulation of deformation in some areas inside continents that will lead to earthquakes in the future. At plate boundaries we see that faults accumulate elastic energy that is measurable. And we know that this energy will be released during earthquakes to come. The system is simple in a way. But what about geologically stable continents? There was a big debate some years ago whether or not the same would occur inside continents.

We were able to show, and I think everyone agrees on that now, that this is not the case. Areas in stable continents that are prone to earthquakes are not building up seismic energy as we speak. Which means that if earthquakes happen in those areas, and they do, they are releasing elastic energy that is stored in the crust over a very long time. Although this is not yet proven –it is hard to do so but we are working on it!. I think that we have made a significant step forward in showing that earthquakes in plate interiors are releasing a sort of “fossil” elastic energy. I think this is helping us a great deal in understanding earthquakes.

Another important result, which is more regional, is the question that was standing for many years about the Africa-Somalia plate boundary, which coincides with the East African Rift, a 4000 km series of basins and volcanoes. What is going on across the East African Rift? Is it a plate boundary? If it is a plate boundary, how fast are plates moving across that boundary? What can we tell about the distribution of deformation across that plate boundary? My group was fortunate enough to make significant steps thanks to field measurements. It is very interesting to make measurements that tell you about the ways the Earth works, and something new about it. In particular, on such an impressive geological feature as the East African Rift.

 

What would you change to improve how science in your field is done?
That requires some thinking… I guess the easy answer is more funding. But I think it’s not the right answer. I think most people would say “Give us more money to be able to do a better job”…

I think that at least in the US and even in Europe –obviously, I can not speak for every European country– there is a decent amount of funding to do research in geosciences. One of the problems that I see, at least in France, is that as a discipline we are not attracting as many students as we should. We are the discipline that is going to make our planet a place where we can live –or not– in the next few hundred years. There should be many more students interested in the geosciences, whether this is earthquake hazards, climate change, water resources… I feel that it’s much harder to find interested students than it should be. We need to do a better job at motivating students into geoscience research because this is one of the fields of study that will help make the Earth a sustainable planet for the future.

My colleagues will kill me for saying that.

What you just exposed, goes to some extend in line with my next question: What are the biggest challenges right now in your field?

Installation of a geodetic benchmark for campaign GPS measurement, Klein’s Camp, Serengeti National Park, Tanzania. Credit: Eric Calais

There is always this back and forth in our field between more measurements and more models. Should we make more measurements? Or should we stop, stand back and think about what these measurements actually mean before we set up new instruments somewhere? I think that finding this balance is a challenge in a way, not only in Earth Sciences. Finding the right balance between, how much is invested into developing measurement systems and producing data and how much investment should be made into making sense of the data. At the moment, there is progress being made, but we are underestimating the data revolution in Earth Sciences.

Right now you hear about machine learning and big data and all those words are out and about in the Earth Sciences, as in any other science. But, we need to be much better prepared to what’s already there in terms of data and what is going to come. It’s very challenging to have not only the right algorithms and the code etc, but also the right mindset in place to accept that in the near future a lot of our thinking will be driven by data, perhaps more so than by physics – My colleagues will kill me for saying that (laughs). It’s a challenge and an opportunity.

I could have done something completely different and have been equally happy.

What were your motivating grounds starting as an Early Career Researcher? Did you always saw yourself staying in academia?

It’s important for the younger generation of ECR to realize that 25 years have made a big difference in terms of the job market, to begin with. When I was a PhD student in France, having done a postdoc was absolutely not mandatory to get a job. I did one, but a lot of my colleagues did not. Right now, most early career students go through 1, 2, 3, 4, 5 postdocs and it’s still hard to find a job. Things have changed dramatically.

My expectation was academia. There was nothing else to think about, really. I barely had a thought for a career in the private sector. It was so much driven by my passion and things were going fine, so I could not see myself doing something else. That being said, now, in retrospective, when I think about myself looking forward in terms of an academic career and nothing else, I know that I was wrong in the sense that I could have done something completely different and have been equally happy. The job I did in Haiti with the UN, for example, a few years ago opened my eyes. There are lots of great, fulfilling, and useful things to do as a geoscientist, or with a geoscientific background, outside of the pure academic domain.

There are lots of great, fulfilling, and useful things to do as a geoscientist […] outside of the pure academic domain. […] Be an actor of change, not just a scientist.

What advice would like to you give to Early Career Students?

I’m trying to stay away from the typical advice: be persistent, be creative. That is true, those are important… Both are easy to say, but not easy to do… One advice that I would give, that I was never given is: be a scientist who is a part of this planet. Be an actor of change, not just a scientist.

 

This map illustrates the horizontal surface motions of sites in Asia. Eric Calais, a Purdue associate professor of geophysics, used global positioning systems to measure the precise movements of hundreds of points on the continent to determine how they react to collisions of the underlying tectonic plates. (Purdue graphic/Calais laboratory) – Credit: Purdue University

Interview conducted by David Fernández-Blanco

Meeting Plate Tectonics – Cesar Ranero

Meeting Plate Tectonics – Cesar Ranero

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie!


Meeting Cesar Ranero


Prof. Cesar Ranero is an Earth Science researcher, currently Head of Barcelona Center for Subsurface Imaging (Barcelona-CSI). He owns a degree in Structural Geology and Petrology from the Basque country and he later completed his PhD in Barcelona, emerging himself in Geophysics. Prof. Ranero’s research is marked by a multidisciplinary approach, applying physical methodologies to understand geological processes.

Scientist also have to look for collaboration with the industry.

Ranero giving an outreach talk on fossil fuels at the Centre de Cultura Contemporània de Barcelona (CCCB). Credit: Cesar Ranero

Hi Cesar, after doing research for few decades, what is, at present, your main research interest?

My research interest covers mainly active processes, I am not so interested in regional geology. I see regional geology as a necessary step to understand processes but the main goal of our group is to understand geological processes. For instance, a great interest in our group is the seismogenic zone and the generation of great earthquakes. We have very good examples in the Iberian peninsula, such as the famous 1755 Lisbon earthquake. Yet, nobody knows where the big fault that created this earthquake is located. We have a lot of research to do. But, often to understand local geology you need to integrate it in the big-picture view of processes. This is why we are mainly interested in those processes rather than in regional geology.

The more you know, the more you realize that nearly everything is to be discovered.

Further, I am interested in interacting with the industry. The geological/geophysical community is a relatively small community (compared to medicine, for example). There is out there quite a few industry groups that are doing very similar things in terms of methodologies and approaches (communities working in oil & gas exploration, or the ones working on carbon sequestration, or geothermal energy production…) All these communities have quite a bit of history in the development of methodologies. They usually have much more money and very talented people developing new methodologies. It is very necessary that we participate in their interests. They are often showing interest in what we do. By going to their meetings and talking to them, you can build fruitful interactions. Scientists also have to look for collaboration with the industry, because at the end of the day it is a place where some of our students can find a good job and make a career.

How would you describe your approach and methods?

The approach in our group is multidisciplinary, we combine complementary methodologies. But it is also important to be aware of proper methods to interpret geophysical data (you have to understand different geological methods, for instance, the methods used in structural geology).

Poststack finite-difference time migration line showing the structure of the Cocos plate across the ocean trench slope. Ranero et al., 2003, Bending-related faulting and mantle serpentinization at the Middle America trench, Nature, 425, 6956, 367.

 

What would you say is your favorite aspect of your research?

What stroke me since I started my PhD is how much good work has been done, but how much more needs to be done.
We know a lot because there were many talented people before doing a lot of work. But actually, if you have a sceptical mind, the more you know, the more you realize that nearly everything is to be discovered. If you look at the last 10 years, you realize that a lot of what has been published is incremental science and much had been laid down in previous publications. But also, there are a whole series of new topics coming out and you have to pay attention because those are the topics that really mean a substantial jump forward. Every year there are several new interesting things coming. For example, earthquake phenomena have been an amazing topic in the last years, all these new phenomena explaining how plate boundaries slip. You have to keep a sceptical mind and at the same time search for those topics.

You have to have a sceptical mind.

Why is your research relevant, what are the real world applications?

This is always a good question. We do a lot of basic research and there is always the philosophical question on whether basic research is relevant… When we discovered the laser, nobody knew how relevant this would be in the future. Now, we can not live without it! I am sure that there is a percentage of basic science discovery that might not have any real-world application. But in many cases, it does. Much of what we do contributes to the understanding of natural hazards. But also, we contribute to resolving problems industries and society are concerned with.

Prestack depth migration of a Sonne-81 line projected on bathymetry perspective. Ranero & von Huene, 2000, Subduction erosion along the Middle America convergent margin, Nature, 404, 6779, 748.

 

At this point of your career, what do you consider to be your biggest academic achievement?

I would like to think that it is the next one! (laughs)

I am proud to have been elected as a fellow of the American Geophysical Union. It means I have done something relevant that is appreciated by my peers, and at the same time, it is a great motivation to work even harder in the future.

Also, I have some nice papers that I am proud of (tectonics of subduction zones, the role of fluids on earthquakes, serpentinization of the outer rise). My view is that for most people, after you finish your career and you look back at your many publications, probably only 3-4 papers are really worth it and seriously contributed brand new material.

What would you say is the main problem that you solved during your most recent project?

Since I came back to Spain, 12 years ago, I started to work a lot in the Mediterranean. For many years, the Mediterranean had been a place where people did not want to work because it is too complex. With the help of German groups and others, our group has been able to characterize for the first time the nature of the crust in many systems in the Mediterranean. We have added a new layer of information to understand the evolution of the whole Mediterranean region. I am quite happy with that, we are producing quite a few papers and have some very new ideas, and we have also started to put that together with fieldwork. There has been a lot of on-land work all around the Mediterranean, but rather limited modern geophysical data on the nearby basins. For example, the Apennines are very well known, but the nearby Tyrrhenian, not so much… We worked with the Italian and the German groups and found some new, interesting geological observations.

Cartoon showing a conceptual model of the structure and metamorphic evolution of subducting lithosphere formed at a fast spreading center. Ranero et al., 2005, Relationship between bend-faulting at trenches and intermediate-depth seismicity, Geochem. Geophys. Geosyst., 6, Q12002, doi:10.1029/2005GC000997.

The biggest challenge is to have time to think about new observations of
high quality that challenges the conventional view
.

After being many years active in the academia, looking back, what would you change to improve how science in your field is done?

I think there are significant differences depending on the country, even within Europe, in terms of funding: how research is done, how research careers develop… Some countries, like Germany and France, are doing relatively good in terms of funding. Other countries, like Spain, Italy or Portugal are not. These countries do not have a well-organized structure for funding, so for researchers is difficult to know how to organize funding around their research to succeed. The people that do well, that work hard, that produce, should have the certainty that they will be able to move forward. But today there is a lot of uncertainty, and in these countries, there’s no warranty that people who deserve it, will have their chances. This is a major problem for ECR, and I think a better structure funding and more funding opportunities for ECR are needed.

Regarding European-funded projects, as for example those of the European Research Council, these programs are extremely prestigious, and only the very top are getting these very well funded grants. And yet, it is unclear to me, at least in my community, that the results and papers produced in the context of these programs are of higher quality than those in other funding programs. So, is it unclear to me that this is a system that we should sustain, but that we shall see in the next years. Talking to others, I get the perception that it is now becoming somewhat too prestigious, people even hesitate to submit proposals because they have to invest loads of time into it and is a huge effort that might not even pass the first evaluation, and review comments appear somewhat indecisive. But I might be wrong on this one.

What you just exposed, goes to some extent in line with my next question: What are the biggest challenges right now in your field?

As for the scientific challenges, I think we can look back at the Plate Tectonic revolution. How did it happen? Before it happened, many observations did not have a good explanation because we were lacking the right data. Then, almost suddenly, we got three datasets that nobody had seen before: magnetometers and echo sonars of higher quality coming from the second-world-war related research, and a worldwide seismological network for monitoring within the frame of the Nuclear Weapon Ban Treaty. And of course, these data landed on the right people. But, in my opinion, it was the access to the right data that provided a whole new view on geology.

So, perhaps the biggest challenge we have now is to be able to produce new methodologies of high resolution to look deeper into the Earth. We need to use high-quality new data sets and new observations that could allow to actually challenge the conventional views.

This is very complicated, particularly in the academic world we live in now. Currently, people have to write several papers for their PhD, and immediately after, in the postdoc period, they have to produce a massive number of papers to at least have a chance. In these circumstances, you can simply not think long enough in a complicated problem. There’s little time to think about what the main fundamental problems are that you want to solve. You have to be a paper-producing machine, and this is detrimental to their quality. You might manage to be someone that is highly productive but, in that frame, it is unlikely that you will often produce major quality. There’s too much pressure on ECRs. So, a challenge is to have time to think about how to obtain new observations of high quality that can change conventional views.

Pre-stack depth-migrated line IAM11, with arrows and numbers indicating the average dips of the block-bounding fault segments exhumed during rifting. Ranero & Pérez-Gussinyé, 2010, Sequential faulting explains the asymmetry and extension discrepancy of conjugate margins, Nature, 468, 7321, 294.

You have to be a paper-producing machine, and this is detrimental to their quality.

What were your motivating grounds, starting as an Early Career Researcher? Did you always saw yourself staying in academia?

I actually thought of going to the industry when I finished university. But I was lucky enough to be introduced to Enric Banda, my PhD supervisor, who had a big picture of geosciences, and he made a real impression on me and made me change my goals. Once I started my career in science, I quickly realized that there was a lot to be done. After two-three years into my PhD, thanks to a nice data set and some good results that were coming out, I definitely saw myself staying in academia. I looked for funding before finishing my PhD and I was lucky to get a Marie Curie, which was not even called like that at the time. I was lucky to work with relatively large groups, and with good funding. There was a good moment, also for industry. Funding was not a major issue for me for many years, so I could spend my time doing the research I wanted. At present, early careers are much more complicated, and you have to really like it to keep on pushing for it.

What advice would you like to give the ECS?

Be ambitious, think big. Don’t be afraid of making mistakes. And above all, be sceptical, completely sceptical about everything. Don’t pretend you know more about what you know, but be sceptical. Because, almost for sure, no matter who did the work, it can be improved, and in most cases, to a great extent. And be open, talk to everybody.

 

Researchers of the Barcelona Center for Subsurface Imaging. Credit: Cesar Ranero

 

Interview conducted by David Fernández-Blanco

Meeting Plate Tectonics – Anne Davaille

Meeting Plate Tectonics – Anne Davaille

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie!


Meeting Anne Davaille


Anne Davaille majored in Physics and continued with a PhD in Theoretical Physics of Fluids, jointly at the University Pierre et Marie Curie and the Institut de Physique du Globe de Paris (IPGP). She investigates convection in strongly temperature-dependent fluids. After her PhD, she went to Yale for a postdoc and she currently holds a CNRS-position at the FAST Laboratory of University Paris-Sud, France.

Research is ideas plus craftmanship. It should be fun and you have to enjoy it to do it.

Anne Davaille. Credit: Anne Davaille.

Anne, what are your research interests and what methods do you use for your research?

Fluid mechanics is my main research area. I study convection in complex fluids, and I use this framework to understand mantle convection and the convective evolution and cooling of planets. My main approach is through laboratory experiments. But then I use and/or build some theory to interpret the experimental results, to derive a physical understanding, and finally to make inferences for geodynamics. All the way, numerics are also involved, to treat the experimental results, or to quantitatively apply the results to planets.

 

No matter what fancy stuff you do, if your data is not good, you are losing on what you are going to get

You have significantly advanced fluid dynamics within the geosciences. Up until now, what do you consider your biggest scientific achievement?

It is probably the works that we did on thermo-chemical plumes in two-layer convection models. We showed that convection in a mantle heterogeneous in density and viscosity could produce several types of plumes, and therefore several types of hotspots. More recently, we have been able to observe different ways of subduction initiation from convection in complex fluids. Plume-induced subduction could be occurring on Venus right now, and might have been important in the Archean Earth. On the side, I am also very happy with the techniques we developed to measure simultaneously and in situ the temperature and velocity fields in the experiments. It really helped us to push lab experiments forward and get a quantitative understanding of the processes we observed.

Different types of plumes and hotspots, depending on the presence of density heterogeneities in the mantle. From Davaille, Nature, 402, 756-760, 1999; and Davaille, Girard & Le Bars, EPSL, 203, 621-634, 2002.

 

After all the time you have spent in science, you have seen many questions answered and more questions rise. What is the biggest challenge in your field that we face today?

Until now, we still have not solved the question ‘why do we have plate tectonics?’ from a physical point of view. On what scale do we need to look for that answer? Grain scale? Or meso-scale, since the lithosphere is quite heterogeneous (e.g. faults, dikes,…)? To get plate tectonic behavior, and therefore the strong localization of deformation, we need a non-Newtonian rheology. From my experience, fluids presenting this particular behaviour are very often mixtures, and their effective behaviour on the large scale can be quite different from their local microscopic behaviour. Moreover, the history of this structure can also strongly influence the large-scale behaviour. With the theoretical understanding we have today, we still cannot model well these behaviours, and therefore answer the plate-tectonics question. I don’t know if we shalll find the answer in theory first, I don’t think that is necessary. It will require most probably a mix of theory, numerics, and data, both experimental (where you can observe and measure all the scales, from the grain to convection) and geological (the “field truth”). Once we do have that answer, we shall gain a better understanding of the other planets and satellites as well.

Plume-induced subduction obtained in FAST laboratory in a climatic chamber. From Davaille, Smrekar & Tomlinson, Nature Geosc., 10, 349-355, 2017.

The one thing we really should stop doing is having this frantic will to publish

Your field of expertise has changed over the years. Is there something you would still like to change?

Oh yes, there are some things I would like to change. The one thing we really should stop doing is having this frantic will to publish. It is an extremely bad habit and it does not generate good research. Especially for the young people that still need to develop ideas and skills, they need time to think and make mistakes, which is not possible with the current mindset of fast publishing. Fast publishing is not beautiful, nor efficient for creative research. Even though the world wants things always faster, doing it faster is not human. We should stop this. What I find the most important is that my work should be strong enough so that people understand what I did and can use this to build on it and move further. For this we need time.

Different regimes of convection in strongly temperature-dependent fluids as a function of the viscosity ratio and the intensity of convection (Rayleigh number). The temperature structure in the sugar syrups is visualized by Thermochromic Liquid Crystals. From Androvandi, Davaille, Liamre, Fouquier & Marais, Phys. Earth Planet. Int., 188, 132-141, 2011.

 

When you were in the Early Stages of our career, what were your expectations for your future?

When I was 7 years old, I learned about plate tectonics. Later, the operation FAMOUS was happening and at this young age I found that fantastic and I wanted to know more. That was one of the reasons why I went into physics. I think that during my career I have been very lucky. Once I got my degree, I thought that before getting a job, I wanted to do a PhD in a very specific topic ‘Convection in complex fluids and planets’. After that we would see. I did not really have any expectations, but I thought, if I can do it maybe it will work and that would be great. Somehow it worked and so I continued working in it, and it is still great fun!

You have to be very demanding, very rigorous if you want to succeed

The last question for today’s Early Career Scientists: what advice would you like to give the ECS that would like to stay in science?

Well, first I think that research is ideas plus craftmanship. It should be fun and you have to enjoy it to do it. But craftmanship is demanding. I have a small anecdote here. I once did an internship at Schlumberger. I worked with experiments and my supervisor at the time told me ‘if you put shit in, -(meaning noise)-, you will get shit out’. My advice would therefore be that no matter what fancy stuff you do, if your data is not good, you are losing on what you are going to get. So for experimental or numerical modelling, if you are not demanding, or only short-term, you may get away with it for a while, but on the long run, you will not last. You have to be very demanding, very rigorous. I think that’s the best way to succeed.

 

Anne Davaille. Credit: Anne Davaille.

Interview conducted by Anouk Beniest

Meeting Plate Tectonics – Roger Buck

Meeting Plate Tectonics – Roger Buck

These blogposts present interviews with outstanding scientists that bloomed and shape the theory that revolutionised Earth Sciences — Plate Tectonics. Get to know them, learn from their experience, discover the pieces of advice they share and find out where the newest challenges lie!


Meeting Roger Buck


Roger Buck is a Research Professor at the Lamont-Doherty Earth Observatory at Columbia University, in New York. His interest lies in developing theoretical models for processes that affect the solid earth. He also studies deformation patterns and topography on other planets, such as Venus.

The key is to look for areas where new data shows that there are important things we don’t understand, things that still surprise us.

After being active for several decades, what is currently your main research interest? How would you describe your approach and methods?

Broadly, I work in Geodynamics. In a lot of different aspects to it. I started doing work on planetary science and mantle convection. Now I work mostly on the mechanics of faulting and of magmatic dike intrusions, particularly focussed on continent breakup and mid-ocean ridges.

 

Roger Buck – Deploying GPS instruments to understand the mechanics of dike intrusions in Afar, Ethiopia. Credits: Roger Buck

 

What would you say is the favourite aspect of your research?

What I find really satisfying is trying to find geologic phenomena or structures that look very complicated, but where there is actually a fairly simple underlying physical mechanism. It is particularly satisfying to find a fairly simple mathematical expression describing the mechanics of processes that otherwise might look quite complicated.

I always hope that, on the long term, explaining things better is good in itself

Why is your research relevant? What are the possible real world applications?

That’s difficult to say in a lot of cases. Just explaining how structures got to be there might not have immediate effects. But, I always hope that on the long term explaining things better is good in itself. Understanding how the Earth works can help us dealing with hazard mitigation. Some of the work that we are doing recently deals with the tectonic processes that are related with earthquakes. That might help us understand the different kinds of earthquakes that happen in different areas.

 

Roger Buck – Physical experiment with gelatin, testing how magma intrusion could trigger continental breakup. Credit: Roger Buck

What do you consider to be your greatest academic achievement?

In airplanes, I tell people that “I work on areas that are splitting apart and on what allows them to split apart”. Probably the single cleanest example was a controversy that came up in the 1980s about what people often refer to as “low angle normal faults” that are associated with rocks brought up from great depth in the crust in core complexes. Over a number of papers, we showed that a lot of these structures that are low angle now, probably initiated at high angles, in ways that are very easy to understand mechanically. They evolved in a way that it’s just a consequence of normal extensional faults extending over long distances. It was very satisfying to chip away that problem from a kinematic viewpoint, and then from a more basic, mechanical point of view. Much of his work was done with excellent colleagues, like Luc Lavier and lately with Jean-Arthur Olive, on numerical simulations of these processes.

 

What would you say is the main problem that you solved during your most recent project?

I’ve been working with a very bright student on the Tōhoku earthquake that happened in March 2011 in Japan, where there was really unprecedented data (the Japanese had many geophysical instruments both on land and underwater). One of the things that was unexpected was that in the upper plate, in the lithosphere above the subduction interphase, the predominant aftershocks over a broad region (about 200 km wide) were extensional earthquakes. This had never been seen before. We have been working with simple ideas and numerical models to explain these extensional earthquakes. Our idea is that it is related to the long term (millions of years timescale) changes in the dip angle of subduction that basically bend the upper plate. We don’t have a clear connection with the extensional deformation that might have been related to the excessive size of the tsunami that was produced, but there could be some relationship. We certainly have not solved this problem but we have a promising hypothesis for one part of the Tōhoku earthquake.

It is very important to continue support for very basic work.

After being many years active in academia, looking back, what would you change to improve how science in your field is done?

Oh, that’s a hard question. A lot of things over the years have been done very well, I think. Like fostering international collaboration in science and that there has been fairly healthy support for science, in a lot of countries, including the United States. It is very important to continue support for very basic work. There has been a retreat from supporting multi-channel seismic work in the ocean in recent years, but this is one of the best ways for us to illuminate the structures produced by tectonic processes. At the same time, increased computer power allows us to get better resolution of structures, based on essentially the same data. However, we still need to collect new data.

The key for big advances is often new technologies

Roger Buck – Deploying seismometers across the Okavango Rift. View on the Victoria Falls. Credit: Roger Buck

 

What you just exposed, goes to some extent in line with my next question: What are the biggest challenges right now in your field?

Uh! These are pretty challenging questions, that’s for sure!

I think there are great and exciting challenges in things I don’t work on myself. The fact that geodesy has improved so much in recent decades and we are learning so much more about plate boundaries. I remember the wonderful talk of Jean-Philippe Avouac during the symposium in Paris, he emphasized how much we have learned. Many seismic gaps are in places where we don’t see traditional seismic activity: large earthquakes or fast earthquakes. We now know that they are slow earthquakes and slow slip events. Understanding where they occur and why we have different kinds of earthquakes in different places along subduction zones is an area that a lot of people have recognized is very important. I think the key to big advances is often new technologies. Geodesy, both on land and submarine, combined with imaging offers terrific hope for a better understanding of major earthquakes. For example, we don’t have a good clue on why some big subduction earthquakes produce very large tsunamis and others not so large tsunamis. These are huge challenges.

 

What were your motivating grounds, starting as an Early Career Researcher? Did you always see yourself staying in academia?

I was always kind of academically oriented. I liked the idea of doing research. I started in Physics and liked it a lot, and then I started taking Geology and liked Geology a lot! I was at university in the mid-1970s and there was a lot of excitement about applying plate tectonics to solve different problems and it seemed very exciting… I am definitely not a good field geologist, but I love being in the field. I think it is important for people doing theoretical work to actually understand the data that they are working with and where it comes from, and the great skill it takes to collect and interpret data. But I realized very quickly that this wasn’t my strength. The key is to look for areas where new data is showing that there are important things we don’t understand, things that still surprise us. That is one of the encouraging things that I’ve seen through my career: repeatedly, with new measurements, we had total surprises. We have seen things we did not expect.

Follow things where you have the potential to make some contribution

What is the best advice you ever received and what advice would like to you give to Early Career Students?

Oh boy!  One piece of advice I got about writing papers that deal with models is particularly good:  You should very clearly separate observations from model assumptions and model interpretations. Not mixing these three things up is something that I certainly struggle with it, but it is something that keeps papers clear and crisp.

The obvious piece of advice that you hear very often and that I certainly tell people: You are typically going to like things that you have some aptitude for. So, follow things where you have the potential to make some contribution. Find something that you really do feel good about doing and you are going to feel good about it if you are somewhat capable of doing it.

 

Roger Buck in Egypt – Credit: Roger Buck

 

Interview conducted by David Fernández-Blanco