Category Archives: Blog

3rd Virtual Geosciences Conference

The 3rd Virtual Geosciences Conference took place in Kingston (Ontario) on 22-24 August 2018.  This conference is at the intersection of geomatics, visualization, computer vision, graphics and gaming, as well as virtual and augmented reality with applications to a range of geoscience subfields, such as geological mapping, geomorphology, geohazards, glaciology, volcanology, tunnelling, and mining. It was organized at Queen’s University, by Ryan Kromer, a former PhD student of Lausanne and Queen’s universities. 


MH Derron, S. Buckley, J. Chandler, M. Jaboyedoff and R. Kromer (Chairman of the 3rd VGC)

The first  VGC conference was in Lausanne in 2014 and then in Bergen in 2016. These events are fantastic opportunities to learn how new technologies can be used  in geosciences, gathering together people from different horizons. 

http://virtualoutcrop.com/vgc2018

Optimizing the use of 3D point clouds data for a better analysis and communication of 3D results. François Noël, Marc-Henri Derron, Michel Jaboyedoff, Catherine Cloutier  Jacques Locat
Infrared Thermal Imaging for Rock Slope Investigation – Potential and Issues. Marc-Henri Derron, Antoine Guérin, Michel Jaboyedoff

Inventory of shallow and spontaneous landslides and improvement of the methodology to establish hazard and risk maps for the Canton of Vaud

On contrary to hazards which have defined return time for establishing natural hazard maps (for example rock falls or floods), there is no similar methodology for shallow and spontaneous landslides. One way to improve the current methodology is proposed by Cedric Meier,  Marc-Henri Derron, Michel Jaboyedoff from RISK-UNIL and Christian Gerber, Veronica Artigue and Melanie Pigeon from the Vaud county administration. It includes the definition of 7 pilots zones based in Jura, Plateau and Alps, on riverbanks or mountain slopes. Based on the new airborne LiDAR acquisition, a former inventory from 1889 to 2013 and basics documents such as geological and topographical maps, air photos, about 110 landslides were registered.

Shallow landslide in the area of Ollon in 2018

The parameters of the source zone of the landslide, like length, width, estimated depth, area, slope angle and propagation angle (Farböschung) were recorded. For each landslide, 3 different volumes (with half-ellipsoid method, elliptical paraboloid method and Sloping Local Base Level or SLBL method, method developed and applied currently at the Institute of Earth Sciences, ISTE – UNIL) were calculated. A volume-frequency distribution, approximated by the Power Law site specific, but also depending on the slope type was developed. Figures showing the probability of the estimated depth or the volume depending on the area of the source zone were also prepared. For the propagation, only 4 % of the landslide have a propagation angle greater than 13°.

 
Probability of max depth in function of the surface area of the landslide

REFERENCES

Jaboyedoff M., & Derron M.-H. 2005: A new method to estimate the infilling of alluvial sediment of glacial valleys using a Sloping Local Base Level, Geogr.Fis.Dinam. Quat., 28, 37-46. 
VD (2017) : http://www.geo.vd.ch/theme/dangers_nat_thm

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

Risk group @ EGU 2018 in Vienna, Austria

The Risk Group participated in the European Geosciences Union (EGU) General Assembly in Vienna, Austria, on 08 April to 13 April 2018. This meeting was a great success, with 4,776 oral, 11,128 posters, and 1,419 PICO presentations. 15,075 scientists from 106 countries participated.

As usual, attending The European Geosciences Union (EGU) General Assembly in Vienna is an amazing opportunity for our group to be an interactive part with the huge platform of experts and scientific researchers from over the world and from different fields. The Risk Group people presented 10 contributions as first authors whose titles are below.

1 Oral

  • Optimizing rockfall simulations by combining high-resolution gridded digital terrain models with 3D point clouds. François Noël et al.

1 Pico

  • Using average velocities of deep-seated landslides to develop intensity-frequency scenarios. Michel Jaboyedoff et al.

8 Posters

  • Coupling 3D rockfall propagation to the spatio-temporal frequency for a realistic rockfall hazard mapping. Cécile D’Almeida et al.
  • SFM photogrammetry for rockfall hazard evaluation in a zero data site (acase study of a touristic area of northern Tunisia). Mariam Ben Hammouda et al.
  • Urbanized areas, natural hazard and risk in Rwanda. Emmanuel Nduwayezu et al.
  • Axisymmetric granular collapse: underlying invariance of granular dynamic? Emmanuel Wyser et al.
  • Inventory of shallow landslides in regard with their frequency in the Canton of Vaud (Switzerland). Cedric Meier et al.
  • Finding the best locations of monitoring devices based on visibility analysis with 3D point clouds. Teresa Gracchi et al.
  • Practical application of an open-source, web-GIS platform (RISKGIS) in learning risk management of geohazards. Zar Chi Aye et al
  • Assessment of potential pollution of an unconfined aquifer in Abidjan by hydrocarbons. Amenan Agnès Kouamé et al.

     

 

 

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