Dr Sam Poppe is a structural geologist and researcher of volcanic plumbing systems. He has been a VIPS enthusiast since 2012 before he started his PhD at the Vrije Universiteit Brussel in Belgium. It was here that Sam began developing a series of analogue experiments of magma intrusions – involving the injection of a viscous fluid into a granular solid. After being involved in different projects all over the world, Sam is now a researcher at the Space Research Centre of the Polish Academy of Sciences, where he investigates crustal deformation due to magma intrusions beneath, using a variety of approaches.
Back in 2022, Sam gave a VIPS webinar on his current research, in particular the ongoing development of the analogue intrusion experiments – don’t worry if you missed it, his talk can still be watched on YouTube! Since then, Sam has now joined the VIPS committee as the representative for Equality, Diversity, and Inclusion (EDI). Here is more from Sam, in his own words, on his research, how rocks are like pasta, and his new VIPS role.
How would you describe your research and why it matters?
Very broadly I look at how magma makes volcanoes deform, and how we can use a deeper understanding of those processes to understand the signals volcanoes give shortly before they erupt. By doing these detailed studies, we hope to better forecast future events. I’m not directly contributing to volcano forecasting, but I’m hoping to inform the forecasting tools that others use… the second line of defence, let’s say! I try to do that through a combination of techniques: laboratory experiments, geological field observations, rock geochemistry, and recently numerical models. This way I am trying to fit all the pieces together.
In your 2022 VIPS talk you show how you create analogue intrusions by injecting golden syrup into granular mixtures of sand and plaster. How well do these materials represent real rock and magma?
We try to simulate real life, large-scale, volcanic processes on a small, manageable scale in the lab. It’s not about using materials with the exact same properties as magma and rock. It’s making sure that the interactions between the different analogue materials are similar to the interactions between magma and rock in nature. As we are scaling down from nature, our materials have to be weaker overall in order to achieve the same balance of forces driving and resisting fluid propagation. The relative strength between sand-plaster mixtures and golden syrup is comparable to that of real-world rock and magma.
Different mixture ratios of sand and plaster represent a range of natural rock strengths and rock “rheologies”. As more plaster is added, the mixture transitions from purely brittle – being able to snap like dry pasta – into a more plastic, deformable, material, like (over-)cooked pasta! This is actually very similar to how the upper part of the crust behaves – it has a brittle-plastic, or brittle-ductile, transition. In my VIPS presentation, I expressed that sometimes it’s not the specific rheology or behaviour of the analogue material that matters, it’s understanding where your experiment falls within the natural spectrum.
(A-E) Temporal evolution of a cone sheet syrup intrusion in a sand:plaster mixture. Left column: vertical slice of reconstructed volumes through the model center. Central column: 3D anaglyphs of the intrusion, to be viewed with blue-red 3D glasses. Right column: Model surface elevation, where the black cross marks where syrup broke through the surface (i.e., eruption); (F) Structural sketch of the final intrusion and induced deformation structures in the overburden through the central slice.
You can read more about Sam’s analogue experiments in his 2019 Frontier’s paper.
Does it inspire you to go out into the field and see magma intrusions with your own eyes?
Making sure to get out in the field, touch the rock, and make small, detailed observations or observing the true scale of intrusions is important for keeping me grounded to what I’m trying to understand – hot, fluid, rock trying to move through a super heterogeneous crust. I think we can get bogged down in our experimental or numerical models, and risk losing touch with either what it all means or where our assumptions might differ from reality.
It’s also just awesome to be out in the field – be it an active volcano or talking to local people who are affected either by volcanic eruptions or by the threatening presence of one. It’s memories from the field that keep me going most in my work. You come back so inspired, or you talk to someone that makes a big impact. There are some trachyandesite quarries in the south of Poland that I recently explored. We went into the last quarry near the end of the trip, turned a corner, and there was a finger pushing into some sediments that were disrupted by a completely vertical contact! You’re just jumping up and down at the pure wonder of the force of nature. It’s good to go in the field and be reminded of that fascination.
What is your favourite thing about your research?
My very first reaction would be to go out in the field – escape from the office, travel the world. But actually, as I think about it, the multidisciplinary combination of the things I do is really awesome. My research has involved fracture mapping in the field, photogrammetry, flying drones, geochemistry, laboratory experiments with CT scanners, and now numerical models. Somehow it all comes together to solve one question, and brings people together who each have their own expertise.
Our community is very multidisciplinary, just look at the VIPS Commission! It’s not just field geologists or laboratory modelers, it’s a mixed bag of people from different backgrounds, all trying to work out what volcanoes look like beneath the surface. I think that is just really cool.
What is your favourite volcano?
That would be Karthala, the first volcano I stepped on. For my MSc thesis in 2011, I flew to the main island of the Comoros – Grande Comore – all by myself, because my supervisor wanted me to look at a complex caldera. He had a contact in the local observatory, and we wrote to them asking if I could visit. They were like “yeah cool just come over” … so I did! I remember the first time I got to the volcano summit after an exhausting climb, and seeing desolate landscape with steam rising, with vegetation still burnt and buried after the 2007 eruption. Standing there, I felt the force and power of nature below my feet.
What drew you to the Equality, Diversity and Inclusion representative role at VIPS?
From 2013-2020 I was involved in co-founding IAVCEI’s early-career researchers network (ECR-Net). During the ECR-Net activities, I got to talk to a broad range of young colleagues from around the world. Later on, during the pandemic year, I attended many virtual debates with other Fulbright fellows supported by the Fulbright Commission Belgium-Luxemburg. These debates focused on discussing the problems in academia with discrimination based on gender, race, sexuality and so much more. Both experiences opened up my eyes to the problems we face in academia. Due to my engagement, the VIPS leaders asked me to take on this role, which I initially doubted as I don’t look the part being a white, male European. But it is flagrantly clear that the drive for change cannot and should not be carried by the minorities that are discriminated against. We all need to play our part in producing positive change.
I am here trying to push for EDI in all its facets and would like to call on any member of the VIPS community. You can help by simply informing yourself about the problems, attending debates, or talking to those colleagues in your department who might face discrimination. The problems are well known, and action is long overdue. My door is open for anyone with ideas towards positive change which I can help push. Right now we are starting with a detailed field trip guideline published on the VIPS Commission’s webpage, and seeing how we can improve the financial support for colleagues from the Global South to attend scientific meetings. IAVCEI and other associations absolutely need to do better. Furthermore, we would like to see more commissions take EDI reps on board, so I will be advocating for that too.
If you’d like to get in touch with Sam about his research or VIPS EDI work, you can send him an email. To find out more about what Sam gets up to, check out his website.
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