What happens inside a landslide?


New Marie Curie fellow Katalin Gillemot applies granular physics knowledge and coding skills to enhance prediction models for natural hazards. The physicist aims to model phenomena that are hardly accessible by field measurements in a landslide, e.g. the exact speed of dry particles or segregation.

Mass waste events such as rock falls, mudslides, soil creep, avalanches, and volcanic flow or hillside slumps change the face of the Earth. If they happen close to human settlements, they are natural hazards that seriously endanger human lives and may cause significant economic impact. Sufficiently understanding and predicting them is an important task both for the scientific community and community leaders around the world.

Marie Curie fellow Katalin Gillemot is working at the Research Group ENGAGE led by Thomas Glade, Department of Geography and Regional Research. She wants to enhance the prediction of natural hazards by connecting different modeling approaches working on different length scales. In her project „Mass Waste Modeling Across Scales“ (MAWAMOSCA) she will design and develop a software based on numerical modeling: „The developed software will  treat a dry landslide as a mass of single particles rolling down a slope that are constantly colliding with each other. This way we hope to access information you cannot measure out in the field“.

Modeling segregation processes

When particles are flowing down a slope they might segregate. That also happens for example in your box of breakfast cereals, when you shake it: the bigger particles such as nuts and raisins end up on top of the smaller sized oat flakes. Segregation can occur when moving particles differ in size, but also if their shape, density, roughness or any other physical parameters vary. Rocks, pebbles and soil in a landslide are therefore susceptible to segregation. Modeling or measuring such phenomena requires very detailed approaches like the numerical model developed in the project.

Katalin Gillemot, born in Hungary, likes to go to the mountains and has always been fascinated when she spotted a small avalanche or landslide during a ski tour or hiking trip. Her interest and motivation is to answer important questions: Why did a landslide take a certain path? Why did it go a certain distance and then stop? Did segregation have any effect on this? Where did it pick up speed and material depending on the morphology of the landscape? The last three years she worked at the Wigner Research Centre for Physics of the Hungarian Academy of Sciences. She conducted experiments and simulations to see what happens, when granular material (e.g. plastic beads or glass rods) segregates or flows down a small slope.

Improving hazard event prediction

In real life, mass waste events are far bigger in scale, but Gillemot will see how different scales could be connected. During her research stay in Vienna, from October 2017 to October 2019, she will also visit a research group for large scale experiments in Strasbourg (France) and an avalanche research center in Davos (Switzerland) in order to investigate if the model can be applied to snow avalanches: „I hope our work will yield better predictions in the future and bring geoscientists and granular scientists together on the way", Gillemot says.

A landslide seldom consists of dry particles only. Usually earthen material comes down mixed with water.  Once Gillemot’s “piece by piece” model is in place, she will compare the modeling results with established large scale continuum models that are already in use at the ENGAGE Group. Past mass waste events will be simulated both ways. By comparing their results the researchers hope to get a better understanding on landslide dynamics for a better hazard prevention in the future.

Rockslide in mountains
Rockslide in the Albanian Alps - cropped copy (Copyright: Katalin Gillemot)
Rockslide in mountains
Rockslide in the Albanian Alps - full size image (Copyright: Katalin Gillemot)
Navigating a rockslide in the Pirin mountains, Bulgaria (Copyright: Katalin Gillemot)