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Tectonics and Structural Geology

Tectonics and Structural Geology

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

The Netherlands: In search of the oldest rocks of a muddy country

The Netherlands: In search of the oldest rocks of a muddy country

Technically speaking, the Netherlands isn’t really a city, even though it is the most densely populated country in the European Union and one of the most densely populated countries in the world, with 488 people/km­2. It is a delta, and for many people geology is not the first thing that springs to mind when thinking about the flat countryside. Large parts of the country have been more often below sea level than above.

The Netherlands, aka the flat country, seen from the air…

…and on the ground. Credit: Anne Pluymakers.

 

 

 

 

 

 

 

However, below the centuries of accumulated sand and clay, there are real rocks – rocks that form extensive reservoirs, for hydrocarbons (such as the Groningen reservoir, one of the world’s largest onshore gas reservoirs), potential CO2 storage reservoirs, as well as reservoirs now of interest to recover geothermal energy. It is the interest in these reservoirs that inspires many companies and the Dutch Geological Survey to figure out what lies below our feet. There is a publicly available database, the DINO database, which provides a view of the Dutch subsurface. It has been constructed using more than 135 3D seismic surveys and over 577.000 km of 2D seismic lines, as well as 1305 wells (www.dinoloket.nl).

Left, a map of the Netherlands, with the approximate location and length of our cross sections indicated (Based on Netherlands with Provinces – Multicolor, by FreeVectorMaps.com). On the top right, a cross section through Amsterdam, with the formations as mentioned in the text. The same formations can be found in the south, but then at the surface. The Heimansgroeve, with the oldest outcropping rocks of the country, are part of the Geul subgroup, indicated with a red dot. (Cross sections from https://www.dinoloket.nl/ondergrondmodellen)

 

Everyone who visited the Netherlands will most likely remember the narrow merchant houses lining the many canals of Amsterdam. These houses are actually built on wooden piles, which are grounded in a sand layer at about 12 meters depth. Drawing a N-S profile through Amsterdam, we dig through many different deltas, swamps and bogs, showing thousands of years of rising and falling sea level. It is then no surprise that many of the mid-19th century houses are now tilted. Digging down in Amsterdam, it takes about 1000 meters until we find the first solid rock, the Upper and Lower Germanic Trias Group (RB, RN), consisting of clay-, sand- and siltstones. Below, there are relatively thin layers of the Zechstein and Rotliegend groups (red and pink), which contain the many on- and offshore hydrocarbon reservoirs found in Dutch territory. The lowest formation of interest (light and dark grey in the cross-sections above) is the Limburg group, in Amsterdam at 2 to 5 km depth. This is where we are heading! But instead of digging up Amsterdam, we travel south, to Limburg. This is the most southern province in the Netherlands, and as the map shows, it is wedged between the Belgian and German border. It is a region with a lot of tourism, and a great place to practice cycling uphill. This gently sloping countryside is the Dutch version of the Belgium Ardennes nearby, which are influenced by the Hercynian orogeny.

The Heimansgroeve was a quarry more than 100 years ago. Today, it is a geological monument. Credit: Anne Pluymakers.

The ancient castle of Valkenburg, a touristic town in Limburg. It was almost entirely built with the yellow marls from the region. Credit: Wikipedia.

The most famous rocks of Limburg are the yellow marls, remnants of a tropical sea and of Upper Cretaceous age. Even though they are soft, they have been used for centuries as building stones, where in the centre of the touristic little town of Valkenburg an ancient castle is almost completely made up out of marl. In the hills around this town hundreds of kilometres of tunnels have been excavated.  When excavated 100 to 150 years ago, one cubic meter of marl used to cost 7 cents – though now a staggering €800,000 euro. Since the rocks are so soft, the only purpose for mining them nowadays is restoration.

It is in this region that we find the oldest outcropping rocks of the Netherlands. They surface in the Heimansgroeve, and are from the Geul Subgroup (dark grey in the cross section) and Carboniferous in age. The depositional setting of these rocks, consisting mainly of sandstones, coal layers and shales, ranged from deep basin, via prodelta, to delta front. Planning a visit to the outcrop with the oldest rocks of the Dutch mainland is surprisingly easy. From the parking lot of campsite Cottesserhoeve (paid parking) it is a leisurely walk towards the river Geul, and then a short walk along the river before we see the outcrop. This outcrop is part of the Heimansgroeve, a former quarry, northwest of Cottessen. In the early 20th century, this quarry was used to mine road-building material, and in 1910 it was discovered by the geologist Eli Heimans.


Fun fact: this region led to one of the first Dutch popular science books on geology, ‘Uit ons Krijtland’, published in 1911. It describes the countryside near this quarry, and encourages people to visit. In 1936, the Heimans quarry was enlarged by the geologist Willem Jongmans for research purposes. Nowadays it hosts a seismological station, to register the occasional earthquakes.


Tilted layers, slickensides and precipitation in open veins. All the features one would look for in the field are present, also in this outcrop in the flatlands! Credit: Anne Pluymakers.

Even though structurally it is not the most exciting place, it still shares many of the features a geologist looks for in the field. The quarry comes with a signpost explaining the geology, for any amateur- or potential future  geologists passing by on a sunny day. Scurrying around, some other small details can be seen; all the features a wandering geologist is hoping for when out rock-hunting. Several places contain slickensides, an indicator for fault movement. For the mineralogist, there are plenty of tiny crystals to be found, showing fluid movement and precipitation in what must’ve been open fractures.

This outcrop shows you don’t have to dig that deep to witness real rocks in a country that is mainly known for being a Delta. So, next time you travel to the Netherlands, why not trade a touristy and overcrowded Amsterdam for a rock-hunting visit in the gentle sloping hills of the South?

 

Introducing our new blog team!

Introducing our new blog team!

After three succesful first years of the Tectonics and Structural Geology blog, it is time to bring our platform to the next level! To provide you more frequent content over a wide range of topics, we invited some new people to join our team. We are still always on the lookout for new guest authors and/or team members, so let us know if you want to contribute! So, what will you be reading on our blog? We will continue the successful Minds over Methods and Geology in the City series, but we have some great new things coming up as well. Since our Meeting Plate Tectonics series is coming to an end, we plan on including new interviews with scientists from the TS field, that will hopefully continue you to inspire you. And we are very happy to have brought back to life our Features from the Field series, where we discuss common structures in the field in an accessible way. Curious to know about the other new content of the blog? Stay tuned!

So, who are those people behind the Tectonics and Structural Geology blog?

 

Elenora van Rijsingen

I am a postdoc in geophysics at École Normale Supérieure in Paris, France. In my research I focus on seismotectonics, using various methods to understand more about earthquakes in subduction zones. I am fascinated by nature, and especially the power of it. Thinking of what nature is capable of reminds me of how small us humans actually are, and helps me to put things in perspective. I have been part of the TS blog since the beginning, trying to create continuous content and to bring in new people. I love editing blog posts, such as the Minds over Methods blogs, interacting with other scientists about their work and learning many new things. I occasionally write blogs myself as well, such as the Mind Your Head series about mental health in academia, a topic I believe deserves more attention. Please contact me via e-mail if you have any questions or ideas about the blog.

 

David Fernández-Blanco

I’m an early career tectonicist that likes to mingle with other disciplines… and making lists. My big goal in life is to understand how the Earth’s vertical motions evolve in time. To answer this question, I do 3 things that I love. [1] Fieldwork, especially in islands and other areas where I might get burned and I have to hand-speak for anything I might need; [2] Mingle things around using bits and pieces from other disciplines, especially geomorphology, stratigraphy, geodynamics. [3] Take up the challenge of geo-communication and translate our geeky, scienc-y, sometimes complicated geo-knowledge to a more general audience. That’s maybe my favourite 3-item list! (I said I like lists, remember?). I also like music, movies, travelling and drinking with my friends, just like every Tom, Dick and Harry. I’m currently the ECS TS Representative, so get in contact via e-mail or reach me at @_GeoDa_ or visit my webpage. Rock on!

 

Derya Guerer

I am a Lecturer in Earth Sciences at the School of Earth and Environmental Sciences, University of Queensland, Brisbane, Australia. My research evolves around tectonics and the evolution of Earth’s lithosphere at various spatio-temporal scales. I combine field-based observations (structural geology, stratigraphy) with laboratory analysis (U-Pb geochronology, paleomagnetism, micro-structural analyses) to build kinematic reconstructions and compare those to the structure of the underlying mantle imaged by seismic tomography. My current research projects focus on subduction-dominated records in the Tethyan region (with focus on Turkey, Iran and Ladakh Himalaya) and recently the SW Pacific realm. As part of the blog team I am happy to edit blogs, particularly for the ‘Minds over Methods’ series and also to occasionally contribute myself. In my free time, I enjoy the outdoors, travel, food and a good cup of coffee with friends. You can reach me via e-mail.

 

 

Anne Pluymakers

I am a post-doctoral researcher in the Rock Mechanics Lab at TU Delft, in the Netherlands. My work-related hobby is figuring out how rocks break, and how fluids affect fracture dynamics. My main rock of interest is limestone at the moment, but I also happily work on related topics, such as what do fractures in natural rocks look like, and imaging projects on fluid flow. I  mostly do laboratory work, and any associated microstructural investigations. But there are also the occasional field excursions, to not lose touch with geology. In the blogteam I am happy to edit blogs, and also to occasionally contribute myself. Outside of work, I love sitting in the sun with a decent cup of coffee and a good book, or to organize dinners for my friends. You can reach me via e-mail.

 
Samuele Papeschi

I have recently gained my PhD at the University of Florence (Italy) and -before that- I graduated in geology at the University of Pisa. My research is focused on understanding deformation of rocks, investigated in the field and in the lab. I combine classic structural geology techniques, like field surveying, with powerful analytical tools such as electron back scatter diffraction and electron microprobe. I like to share everything from what I am researching to observations from the field. I believe, indeed, that research is not done if it’s not shared! I also run one of the most useless geoscience facebook pages: Geology is the Way. The field is my natural habitat and I will share snapshots from it in the ‘Features from the Field’ series, hoping that you will enjoy looking at it through my eyes. You can reach me via e-mail.

 

Hannah Davies

I am a PhD student at Lisbon University, Portugal. Using numerical models and GPlates, I am investigating the link between plate tectonics and tides in the deep future and past. It was recently discovered that tides change over geological time scales as ocean basins change shape due to plate tectonics. As an editor and writer of the TS blog I want to bring this newly discovered link between tides and tectonics to an audience which may not have heard of it yet. When I am not doing real science, I am devouring science fiction. I spend a good amount of my free time in coffee shops reading. When I don’t read, I like to explore Lisbon. It is a very old place with a lot of history from the past two millennia so there is always somewhere interesting to find. You can reach me via e-mail.

 

Silvia Brizzi

I am a postdoctoral researcher in the Natural and Experimental Tectonic group at the University of Parma, Italy. My research is aimed at understanding the relationship between geodynamic parameters and the seismogenic behaviour of the subduction megathrust. More specifically, by combining observational and analog modelling approaches, I try to understand if specific (geodynamic) conditions can favour the occurrence of very large earthquakes in subduction zones. At present, I am working (really hard!) to measure and calibrate the rheological properties of innovative materials with complex rheologies to better mimic Earth’s behavior in the lab (yes, The Sassy Scientist, I am actually spending months on this!!). I am really excited to be part of the blog team as an editor. I will also be in charge of sharing our activities on Twitter. In my spare time, I love to read books and binge-watching TV series. Oh, and I also love aperitivo with friends. You can reach me via e-mail.

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

Minds over Methods: The faults of a rift

Minds over Methods: The faults of a rift

Do ancient structures control present earthquakes in the East African Rift? 

Åke Fagereng, Reader in Structural Geology, School of Earth and Ocean Sciences, Cardiff University

For this edition of Minds over Methods, we have invited Åke Fagereng, reader in Structural Geology at the School of Earth and Ocean Sciences, Cardiff University. Åke writes about faults in the Malawi rift, and the seismic hazard they may represent. With his co-workers from the Universities of Cardiff, Bristol, and Cape Town, the Malawi Geological Survey Department, Chancellor’s College, and the Malawi University of Science and Technology, he has studied these faults in the field and in satellite imagery. Their methods span scales of observation from outcrop to rift valley, allowing insights on how rifts and rift-related faults grow.

 

Åke Fagereng looking at rocks by Lake Malawi. Credit: Johann Diener.

Introduction

East Africa hosts some of the longest faults on the continents, yet it is not a well-known location for significant seismic hazard. There is, however, historical record of large earthquakes (> M7; Ambraseys, 1991), and topographic evidence for major scarps (Jackson and Blenkinsop, 1997), so we ask where, and of what magnitude, could future earthquakes occur?

The instrumental record of East African earthquakes is short, and sparse instrumentation only detects moderate to large magnitude events. Recent, seismic deployments have, however, made great progress in understanding active seismicity in the southern East African rift (e.g. Gaherty et al., 2019; Lavayssière et al., 2019). Such studies have demonstrated that the seismogenic thickness – the depth range where earthquakes nucleate – spans the entire crust (up to 40 km depth). This large seismogenic thickness is important; it theoretically means that ~ 100 km long border faults could rupture along their entire length and throughout the thickness of the crust, creating > M8 earthquakes. Such events would have severe impact, particularly given rapid population growth, urbanization, and high vulnerability of the East African building stock (Goda et al., 2016).

There is a scale dependence to fault observations in rifts. On the rift valley scale, active extension broadly follows ancient plate boundaries marked by deformed, metamorphic rocks separating ancient continental building blocks of cratons and shields. However, does the same observation apply to individual faults, and at what depths? Is there evidence for large earthquake events? A hypothesis to test is whether ancient structures control the location and geometry of major rift border faults, and allow them to be long and continuous.

 

The Bilila-Mtakataka fault in Malawi (black), broadly following but locally cross-cutting foliations (red). Map reproduced after Hodge et al. (2018).

Methods and Results

In the PREPARE project, we focus on Malawi as a case study in the southern, non-volcanic, portion of the rift. Although we have established a network of campaign GPS stations, slow extension rates (< 3.5 mm/yr; Saria et al., 2014) imply that reliable geodetic data will take several more years to collect. Similarly, long earthquake recurrence times lead to a question of how representative the instrumental record can be. Therefore, we have explored other methods for understanding fault scarps and the likely behavior of their faults.

In his PhD work, Michael Hodge used a combination of data sets, including satellite imagery and digital elevation models, photogrammetry, and field observations to analyse the major Bilila-Mtakataka fault from outcrop to rift scale. This fault sits within an ancient ‘mobile belt’ and follows these structures in some places, but cross cuts them in others (Hodge et al., 2018). These observations show that the fault only exploited near-surface ancient structures where these were very well oriented for failure, while elsewhere the fault would take another orientation.

 

The Bilila-Mtakataka fault, illustrated by its ~ 10 m high scarp. Credit: Åke Fagereng.

 

To better understand the controls on fault reactivation and how our surface observations relate to faulting at depth, we place our field and satellite observations in a framework of fault mechanics. It is not uncommon that normal fault segments take two strike orientations: one parallel to pre-existing weaknesses, the other perpendicular to the extension direction (e.g. McClay and Khalil, 1998). However, although there is uncertainty around local extension directions, where fault segments in Malawi cross-cut ancient structures they do not seem to have a consistent, extension-perpendicular, strike (Hodge et al., 2018).

Hodge et al. (2018) tested whether a mid- to lower crustal ancient structure could control the average orientation of the Bilila-Mtakataka surface scarp. This test was based on whether model predictions fitted detailed measurements of scarp height and orientation using a digital elevation model. Such measurements are time consuming, but using a semi-automated method, can also be applied efficiently at the scale of multiple faults (Hodge et al., 2019). Here, the model supports a conclusion where long fault scarps form above localized, deep crustal structures, that are locally deflected near the surface. This model allows the long scarps to have formed in multiple smaller earthquakes rather than a single very big one.

 

Field observations of the Bilila-Mtakataka fault, which locally parallels (A) and locally cross cuts foliation (B). Map from Hodge et al. (2018), Michael Hodge and Hassan Mdala study the fault in A (credit Åke Fagereng) and Åke Fagereng measures a fracture in B (credit Johann Diener).

 

Model, simplified from Hodge et al. (2018), showing how upward propagation of a deep structure is consistent with a segmented surface trace, if the fault is deflected by well-oriented foliation locally and near –surface.

Future Work

Newly discovered fault scarps within the Zomba graben, further south in Malawi, furthermore show that fault orientations vary on the scale of multiple faults within a graben. Here, strike variations also lack a clear fit to expected orientations inferred from the rift-wide extension direction. Ongoing studies are now employing similar methods to analyze the relation between fault geometry and pre-existing structures in the field, on the scale of a complete graben, further bridging the outcrop and rift scales.

Geophysical and remote sensing approaches have been and continue to be invaluable to understand the regional and subsurface structure of the East African and other continental rifts. We emphasise, however, that fault scale structural observations aid interpretation of these data and allow deduction of fault growth mechanisms. Our methods in future work will therefore continue to span scales, and root interpretation in detailed fault-scale field studies linked to rift-scale satellite data.

 

Edited by Elenora van Rijsingen

 

References

  • Ambraseys, N.N., 1991. The Rukwa earthquake of 13 December 1910 in East Africa. Terra Nova 3, 202-211.
  • Gaherty, J.B., Zheng, W., Shillington, D.J., Pritchard, M.E., Henderson, S.T., Chindandali, P.R.N., Mdala, H., Shuler, A., Lindsey, N., Oliva, S.J. and Nooner, S., 2019. Faulting processes during early-stage rifting: seismic and geodetic analysis of the 2009–2010 Northern Malawi earthquake sequence. Geophysical Journal International 217, 1767-1782.
  • Goda, K., Gibson, E. D., Smith, H. R., Biggs, J., & Hodge, M. (2016). Seismic risk assessment of urban and rural settlements around Lake Malawi. Frontiers in Built Environment, 2, 30.
  • Hodge, M., Fagereng, Å., Biggs, J. and Mdala, H., 2018. Controls on early‐rift geometry: new perspectives from the Bilila‐Mtakataka fault, Malawi. Geophysical Research Letters 45, 3896-3905.
  • Hodge, M., Biggs, J., Fagereng, Å., Elliott, A., Mdala, H. and Mphepo, F., 2019. A semi-automated algorithm to quantify scarp morphology (SPARTA): application to normal faults in southern Malawi. Solid Earth 10, 27-57.
  • Jackson, J. and Blenkinsop, T., 1997. The Bilila‐Mtakataka fault in Malaŵi: An active, 100‐km long, normal fault segment in thick seismogenic crust. Tectonics 16, 137-150.
  • Lavayssière, A., Drooff, C., Ebinger, C., Gallacher, R., Illsley‐Kemp, F., Oliva, S.J. and Keir, D., 2019. Depth extent and kinematics of faulting in the southern Tanganyika Rift, Africa. Tectonics 38, 842– 862.
  • McClay, K. and Khalil, S..1998. Extensional hard linkages, eastern Gulf of Suez, Egypt. Geology 26, 563–566
  • Saria, E., Calais, E., Stamps, D.S., Delvaux, D. and Hartnady, C.J.H., 2014. Present‐day kinematics of the East African Rift. Journal of Geophysical Research 119, 3584-3600.

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

Features from the Field: Boudinage

Features from the Field: Boudinage

The Features from the Field series is back! In our previous posts, we have shown how rocks can deform during ductile deformation, producing folds. Folds very commonly develop in rocks when rock layers are shortened by tectonic forces in a specific direction. On the other hand, when layers are extended, we develop boudins.

Saucisson is a dry cured sausage (boudin) from France. Did you know that geology is full of food analogies? Indeed, we love barbecues. Photo credits © Nate Grey (Flickr)

Boudins – the term comes from the French word for ‘sausage’ – are fragments of original layers that have been stretched and segmented. They develop in layers that are stronger and more resistant to deformation (i.e. more competent) than the surrounding rocks. In the example shown at the top of the page, the boudinated layer is made up of ‘strong’ amphibolites that are surrounded by relatively weaker quartzites. As you can see, the layering of the quartzites is deflected in the ‘pinches’, as if they where flowing in the gaps of the boudins during the extension. That’s it! During ductile deformation, rocks flow over millions of years in a plastic way.

Different rock types are characterized by a different strength during deformation, which is significantly influenced by temperature, pressure or -very important- presence of water. Boudinage is a very common structure which helps  the geologist understand ‘who is stronger than who?’ and helps them guess the physical conditions at which deformation took place.

Boudinage style can also vary enormously. For example, the eye-shaped boudins shown at the top of the page are called ‘pinch-and-swell’ structures. Indeed, you can notice that the boudins are not entirely separated and are connected by a very thin amphibolite layer, as if they were ‘pinched’ by a finger. This structure suggest that both the boudinated layer and the surrounding rocks are deforming in a ductile way.

However, fracturing can also play an important role in boudinage. In the example shown below, the top layer consists of strong quartz-metaconglomerate that has been boudinated within very weak phyllites (the bottom layer). The quartz-metaconglomerate is fragmented along symmetric (dextral and sinistral) fractures with an offset of several centimeters. The white material filling the gaps are vein of quartz that were deposited during the boudinage process. Note how the fractures are restricted to the metaconglomerate.

 

Symmetric boudinage of a quartz metaconglomerate in phyllites. The gaps of the boudins are filled with white quartz veins (Punta Bianca, La Spezia, Italy). Photo credits © Samuele Papeschi

 

Boudins can be symmetric, as in the example above, or asymmetric, as in the example below, where the boudinated layer is an amphibolite surrounded by weaker micaschists and quartzites. The boudins are separated by small scale sinistral shear fractures and systematically rotated clockwise. In this case, the geologist can obtain information about rock strength during deformation, but also on the sense of shear – which here is top to the right.

 

Asymmetric boudinage of amphibolite (the blackish layer) in dark grey biotite-micaschists and white quartzites (Elba Island, Italy). The amphibolite layers is fragmented by several, sinistral shear fractures. Photo credits © Samuele Papeschi

 

Rocks are not stretched in a single direction. Layers can also be flattened and stretched along 2 directions. When this occurs, you get fragmented boudins surrounded by 2 sets of fractures, as in the last example below. You already know that geologists like food analogies, so are you able to guess the name of this last structure? Yes, it is a chocolate tablet boudinage.

 

Chocolate tablet boudinage: a grey dolomite vein has been stretched along two, nearly-perpendicular, directions. The gaps between the boudins are filled by calcite deposited by fluids (Punta Bianca, La Spezia, Italy). Photo credits © Samuele Papeschi.

 

To sum it up, boudinage is a very important structure when studying rocks in the field, which gives us important insights about deformation, rock strength, pressure and temperature conditions and the sense of shear. Together with folds, lineations and foliations, it represents one of the most important features that can be described in the field.

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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