Category Archives: Blog

Barcelonnette field trip 2018

The field trip on gravitational slope movements for master students took place for the fifth year at Barcelonnette (French Southern Alps) at the beginning of June. During two weeks, the students had the opportunity to study the landslide of Lavalette, rockfalls around Meolans and debris flows in the Riou Bourdoux catchment. The quite intensive program was composed of mapping and terrestrial LiDAR in the field during day times, data analysis and numerical modelling the evening.

Hugo Collomb from RTM giving explanations on the debris flows mitigation measures in the Riou Bourdoux catchment

Once again we benefited from all the facilities provided by the Seolane center (center dedicated to host scientific stays at Barcelonnette), and we had the opportunity of a visit guided by Hugo Collomb of the French Office of Forest (ONF-RTM).

Séolane, Pôle d’accueil universitaire

Tunisian Geological Days on mapping georisks

The Journées de la Géologie Tunisienne was organized by the office national des mines in Hammamet from 23 to 25 March. This year, this conference was dedicated to the mapping of georisks. Mariam Ben Hammouda and Marc-Henri Derron from the group Risk took part to this conference, presenting advances in point cloud processing. It was also the opportunity to visit the Cap Bon area where Mariam is doing her PhD thesis.

Collapsed road at Cap Bon


Although blue sky, that was a chilly week of March

Field trip and visit in Taiwan

Beginning of March was a great opportunity for Marc-Henri Derron to visit sites and colleagues in Taiwan for the first time. Invited by Prof. C.W. Lin (National Cheng Kun Univ. in Tainan) and Prof. R.F. Chen (Chinese Culture Univ. in Taipei), Marc-Henri had the opportunity to visit large landslides in central Taiwan, as well as giving 3 presentations on various aspect of landslide investigation techniques.

Slope conditions, steep and weathered, are drastically different from those encountered in the Alps. This visit was the first one for a group Risk’s member and we are confident it will lead to further cooperation.

3D modelling the oak of Napoléon

The Risk group participed in a study conducted by researchers at the University of Lausanne whose results where published in Nature Plants . Results reveal that the genome of oak Napoleon has evolved little during its first 234 years of existence.

The 3D modelling was carry out using a LiDAR. Terrestrial LiDAR scans were taken around the oak every 60°. The six scans were cleaned from background objects and aligned in order to generate a 1.2 million 3D-points cloud. The mesh from the 3D points cloud was colourized to produce the final 3D oak model.

Sources: Nature Plants, Le Temps, 24Heures, News Unil, Napoleome

Oak of Napoleon from our automatic camera along seasons:

Oak scanning:

3D-printed model of the oak:

Near-infrared image of the oak:

Andorra-la-Vella : Lidar monitoring

The Risk Analysis Group (C. d’Almeida, F.Noël) spent a week in the principality of Andorra to carry out lidar survey. The city of Andorra-la-Vella, located in the hearth of the Pyrenees is a very dense city surrounded by landslides and active cliffs.

Lidar and photographs survey

Lidar and photographs survey of 12 sites were performed. These sites were previously monitored by the Risk Analysis Group (Antonio Abellan) in 2009 and 2012. Exploiting the lidar scans will permit to quantify the erosion activity of the cliffs and detect potential instabilities. The Risk Analysis Group thanks the geo-hazard expert Joan Torrebadella from Georisk-international for his warm welcome, and accompanying during this week.

Lidar scan

Risk Group at the 15th Swiss Geoscience Meeting in Davos, Switzerland

The 15th Swiss Geoscience Meeting, organized by the WSL-Institute for Snow and Avalanche Research SLF and the Platform Geosciences of the Swiss Academy of Sciences SCNAT, was held on 17th and 18th of November 2017 in Davos (Switzerland).

16 different sessions were planned during this meeting and the Risk Group members contributed to several presentations mainly in the “Progress in assessment of hazards and risks in mountain regions” session. Presentations are below:

5 Talks:

Aye Z.C., Artigue V., Jaboyedoff M., Derron M., Gerber C., Lévy S. An open-source webGIS platform for risk management of natural hazards in Canton Vaud

Derron M.-H., Rouyet L., Guerin A., Lefeuvre C., Jaboyedoff M. Imaging of non-gravitationnal movements in rock faces

Franz M., Rudaz B., Jaboyedoff M., Podladchikov Y. Coupling SLBL with shallow water model to assess landslide-generated tsunami hazard at Oeschinensee

Jaboydedoff M., Artigue V., Aye Z.C., Derron M.-H., Gerber C., Lévy S. From the average velocities of deep seated landslides to intensity-frequency scenarios

Noël F., Wyser E., Jaboyedoff M., Derron M. Real-size rockfall experiment: How different rockfall simulation impact models perform when confronted with reality?

8 Posters:

Meier C., Derron M., Jaboyedoff M., Gerber C., Artigue V. Inventory of shallow landslides in regards to their frequency in the Canton of Vaud (Switzerland

D’almeida C., Guerin A., Jaboyedoff M., Hantz D. Model and cartography of the Saint-Eynard cliff erosion by rockfalls

Wyser E., Jaboyedoff M. Dramatic granular impact(s): a plastic- or friction-dominated transition phase

Noël F., Wyser E., Jaboyedoff M., Derron M. Real-size rockfall experiment: A relatively simple method to acquire 3D impact characteristics from video footage

Nduwayezu E., Jaboyedoff M., Derron M.-H, Nsengiyumva J.-B., Twarabamenye E. Pression démographique et outils analyse d’aléas et risques gravitaires au Rwanda.

Ben Hammouda M., Jaboyedoff M., Derron M.H., Bouaziz B. Rockfall hazard evaluation in a touristic area of northern Tunisia using SFM photogrammetry in a zero data site

Voumard J., Derron M.-H., Jaboyedoff M. Characterization of natural hazard events affecting the Swiss transportation networks from 2012 to 2016

1 poster for the “Hydrology, Limnology and Hydrogeology” session:

Kouame A.A., Jaboyedoff M., Goola Bi Tie A., Derron M., Kouamé Kan J. Assessment of potential pollution of an unconfined aquifer in Abidjan by hydrocarbons

The full proceedings volume of VGC2016 is available at: https://geoscience-meeting.ch/sgm2017/wp-content/uploads/SGM_2017_Abstract_Volume.pdf

Scientific stay of Teresa Gracchi in the group RISK

Teresa Gracchi will stay for 6 months in the group RISK at UNIL. Teresa is a joint-PhD student at the Department of Civil and Environmental Engineering of the University of Florence and at the Faculté des Géosciences et de l’environnement of the University of Lausanne, in the framework of the International Doctorate in Civil and Environmental Engineering program. Her research involves the use of innovative techniques for landslide monitoring, such as wireless sensor networks. In particular, she deals with a low-cost and easy to install system suitable for emergency monitoring, based on ultra-wideband technology. During her stay at UNIL, she will focus in viewshed analysis from LIDAR point cloud, to develop a tool that allows finding the best positions to install a wireless sensor network.

Welcome Teresa and we wish you the best for your project

4th Slope Tectonics Conference – Kyoto Oct. 2017

The 4th Slope Tectonics Conference was held from 14 to 18 October 2017 in Japan. It started with two days of presentations at the University of Kyoto and was followed by three days of fieldtrip in the Kii penninsula. As a reminder, the Slope Tectonics Conferences were initiated in Lausanne in 2008 (and then in Vienna in 2011 and Trondheim in 2014).

Michel Jaboyedoff and Marc-Henri Derron took part to this conference with two oral presentations:
3D failure surface and volume estimation of large rock slope instabilities: a review of a bottleneck problem
Slope deformation imaging of sandbox analogue models (LiDAR and InSAR)

Flight at Bondo (GR)

Five people of the Risk Analysis Group went to Bondo, Canton of Graubünden, on 29 September 2017 to make a helicopter flight along the debris flow and cliff collapse of the August event. During a 25 minutes flight from the village of Bondo to the Piz Cengalo through the Val Bondasca, 11’400 pictures were taken by automatically and manually operated cameras . Those data will be used to get 3D models of the area by SfM processing.