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For his PhD, VUB researcher Sam Poppe has carried out a research project on magma intrusion that improves prediction of volcanic eruptions. Not only did Poppe study volcanoes in Oslo and Réunion, he also simulated the movement of magma in his lab and took CT scans.

 

From the moment Sam Poppe stood on the crater of the Carthala volcano in Comoros for his master’s thesis at Ghent University, he says he was ‘sold’. After his geology studies, Poppe committed himself to fieldwork on volcanoes in DR Congo and Rwanda, commissioned by VUB professor Matthieu Kervyn. In 2014, the adventurous scientist started his own research, financed by FWO – Flanders, to study how magma moves. The underground movements of magma deform the earth’s crust, cause earthquakes and ultimately lead to eruption. Poppe: “Magma travels its own route underground. Satellite images show where magma distorts the earth’s crust, but in fact we know too little about how magma moves before it breaks out through the earth’s surface. If you have that information, you can better estimate how close magma is to the surface and when you can expect an eruption.”

 

Syrup in the sandpit

Because this process takes place underground, it is very difficult to investigate, and geologists often rely on dynamic scale models. Based on observations of the 240-290-million-year-old rock of the Oslo Rift, Poppe made a laboratory model in 4D (3D and time). To simulate the earth’s crust, he used a mixture of silica sand and gypsum powder, then injected Golden Syrup into this mixture during short experiments lasting up to an hour. On the small scale of this sandpit, the syrup behaves in the same way as magma does in nature.

 

Radiology meets geology

Injecting syrup into sand had already been done before, but a new feature of Poppe’s research was that he used CT scans to map out the deformations of the subsurface every 20 seconds. Before this, Poppe worked with Prof Nico Buls and Dr Gert Van Gompel of UZ Brussel’s radiology department. The scans show that the deformations and cracks of the earth’s crust are caused in a more complex way than previously assumed.

 

Saving lives

Poppe then tested his findings against satellite images of three 2018 eruptions of the active Piton de la Fournaise volcano on Réunion. With these results, he will soon go to Penn State University in the US, where he plans to refine the computer models that predict volcanic eruptions during a Fulbright-BAEF postdoc. Poppe: “My lab experiments show that the computer models we currently use are not complex enough to accurately predict eruptions. In Pennsylvania, researchers are working on the development of these models. So that’s where I’m going.” With this research, Poppe hopes to save lives in the future. “One tenth of the population lives close to a volcano, often in big cities. A lot of critical infrastructure, such as hospitals and power stations, is also located in unfortunate places. If we can assess eruptions even better, we could avoid many disasters.”

 

Practical

Magma intrusion and related deformation of the shallow earth’s crust in nature and analogous experiments, a dissertation by Sam Poppe with promoters Prof Dr Matthieu Kervyn (VUB) and Prof Dr Eoghan Holohan (UCD University College of Dublin, Ireland).