Category Archives: News

New publication in Environmental Earth Sciences about sinkhole-related risk

by Pierrick Nicolet, Marc Choffet, Marc-Henri Derron, Michel Jaboyedoff and Bertrand Lauraux: “Evaporite sinkhole risk for a building portfolio

Karst-related hazard can be a problem for buildings, especially in the case of evaporite karst. This study aims at evaluating the risk posed by evaporite karst for a building portfolio in western Switzerland, using a susceptibility map and an event inventory. Since the inventory is not complete, different corrections aim at obtaining a frequency of sinkhole events damaging a building as close as possible to the actual frequency. These corrections account for the variation of the building stock during the inventory period, the varying inventory quality among the municipalities and the partial knowledge, even in the best case. This approach is preferred here to estimating spatially the hazard, since the amount of information on the frequency and magnitude is insufficient to draw a proper hazard map. The distribution of loss ratios is also retrieved from the inventory, thanks to the estimated or actual price of the remedial works. Annual losses are then estimated using a Monte Carlo approach, which consists in sampling for a number of damaged buildings from a Poisson distribution, for a distribution of loss ratios and for a building value. Different exceedance curves relying on different hypotheses are presented, and the mean annual loss that the public insurance company might have to compensate is estimated at CHF 0.8–1.5 million.

The article can be accessed on Environmental Earth Sciences website. The full text can also be read on SharedIt

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.

 

Thesis on risk analysis available for download

Pierrick Nicolet defended publicly on the 9th of January his PhD entitled “Quantitative risk analysis for natural hazards at local and regional scales”. The thesis aims at improving the quantification of the potential consequences of natural events and is divided in two parts. The first part deals with risk analysis at local scale, which is particularly useful to prioritize the subsidies of protection measures. When it comes to the second part, regional stochastic models are proposed and are oriented towards the portfolio management for public buildings insurances companies.

Since the thesis was accepted, the full text is now available for download here, and the full abstract is available here.

Risk group @ EGU 2017 in Vienna

The Risk Group participated to the European Geosciences Union (EGU) General Assembly in Vienna, Austria, on 17 April to 22 May 2017. This huge meeting brought together 14’496 scientists from 107 countries with 4’849 orals, 11’312 posters and 1’238 PICO presentations.

It is always an excellent opportunity for our group to meet new people and other scientists we work with during the five days of the meeting. The Risk Group people presented 30 contributions as first authors whose titles are below.

4 orals:

  • Rockfall travel distances theoretical distributions Michel Jaboyedoff et al.
  • Rockfall monitoring of a poorly consolidated marly sandstone cliff by TLS and IR thermography Caroline Lefeuvre et al.
  • Characterization of the deformation and thermal behavior of granitic exfoliation sheets with LiDAR and infrared thermography (Yosemite Valley, USA) Antoine Guerin et al.
  • Optimizing the use of airborne LiDAR data for a better analysis and communication of 3D results​ François Noël et al.

4 PICO:

  • Debris flows susceptibility mapping under tropical rain conditions in Rwanda.
    Emmanuel Nduwayezu et al.
  • Five years database of landslides and floods affecting Swiss transportation networks Jérémie Voumard et al.
  • Three consecutive years of road closures due to natural hazards in the Weisstannen valley, Canton of St-Gallen, Switzerland Jérémie Voumard et al.
  • Experimental insights of liquid impacts onto granular beds of various packings : The packing influence over the excavated volumes Emmanuel Wyser et al.

9 posters:

  • Integrated risk management and communication: case study of Canton Vaud (Switzerland) Veronica Artigue et al.
  • Radiometric enhancements of thermal infrared images for rock slope investigation by coupling with groundbased LiDAR Marc-Henri Derron et al.
  • Landslide-Generated Tsunami model Martin Franz et al.
  • Introducing a moving time window in the analogue method for precipitation prediction to find better analogue situations at a sub-daily time step Pascal Horton et al.
  • Using genetic algorithms to achieve an automatic and global optimization of analogue methods for statistical downscaling of precipitation Pascal Hortonet al.
  • Development of a 3D rockfall simulation model for point cloud topography
    François Noël et al.
  • Understanding three decades of land use changes and a cloudburst in Phewa Lake Watershed, Western Nepal Karen Sudmeier-Rieux et al.
  • Automatic 3D relief acquisition and georeferencing of road sides by low-cost on-motion SfM Jérémie Voumard et al.
  • Preliminary 2D numerical modeling of common granular problems Emmanuel Wyser et al.

Michel Jaboyedoff received the DPRI Award 2017 in Kyoto University

Michel Jaboyedoff reciveing the DRPI Award from thge director of DPRI Prof. Kaoru Takara (Picture from http://www.dpri.kyoto-u.ac.jp/news_en/9141/)

On February 21st, Michel Jaboyedoff received the DPRI Award (Disaster Prevention Research Institute – Kyoto University). He expressed his gratitude to DPRI and Prof. Chigira when he received his award. He delivered a Memorial Lecture entitled: “Emerging Techniques and Impact of Human Activities in Landslide Risk Management: 3D Analysis and Human Induced Landslides” (video). The International Institute for Applied Systems Analysis (IIASA) received this award jointly.

DPRI Award: “The DPRI Award honours individuals and organizations that have contributed towards various joint research projects and activities of DPRI undertaken in Japan and abroad.” DPRI (from http://www.dpri.kyoto-u.ac.jp/dpriaward_en/)

Risk group @ RocExs 2017 – Barcelona

The Risk Group participated to 6th Interdisciplinary Workwhop on Rockfall Protection in Barcelona, Spain, on 22-24 May 2017.
The first two days, we followed the different presentations while the third day, we participated to a field trip in the Monserrat Massif whose theme was dedicated to rockfall management.
Presentations from the Risk Group:
  • 11 years of ground-based LiDAR monitoring in the West Face of the Drus (Mont-Blanc Massif, France) after the little rock avalanche of June 2005. Guerin et al.
  • The effect of slope roughness on 3D rockfall simulation results. Noël et al.
  • Multi-technique approach to assess rockfall propagation: a case study from Les Forges, Jura, Switzerland. Lefeuvre et al.

In memoriam Jacques Bechet

img_9698_2We have recently published two papers written with our former Master’s student Jacques Bechet who died tragically in a snow avalanches on 28 March, 2015. We dedicate these papers to Jacques Bechet (first author). Their content is an expression of his great ingenuity, curiosity and passion for research he shared with his co-worker Julien Duc. We will always remember his enthusiasm and his kindness. We sympathize with his family and with his friend Julien Duc who worked closely with him.

Bechet, J., Duc, J., Loye, A., Jaboyedoff, M., Mathys, N., Malet, J.-P., Klotz, S., Le Bouteiller, C., Rudaz, B., and Travelletti, J. 2016: Detection of seasonal cycles of erosion processes in a black marl gully from a time series of high-resolution digital elevation models (DEMs), Earth Surf. Dynam., 4, 781-798, doi:10.5194/esurf-4-781-2016. PDF

Bechet, J., Duc, J., Jaboyedoff, M., Loye, A., and Mathys, N. 2015: Erosion processes in black marl soils at the millimetre scale: preliminary insights from an analogous model, Hydrol. Earth Syst. Sci., 19, 1849-1855, doi:10.5194/hess-19-1849-2015. PDF

Risk group at the 12th International Symposium on Landslides (ISL)

Four persons of the Risk Group participated to the 12th International Symposium on Landslides (ISL) in Napoli, Italy, on 12 to 19 June 2016. We presented one lecture and three orals. All contributions at the symposium are collected into three books.
It was a great opportunity for us to meet scientists we work with during the five days of the Symposium.

Lecture:
Human-Induced Landslides: Toward the analysis of anthropogenic changes of the slope environment. M. Jaboyedoff et al.

Orals:
Rock slope pre-failure deformation database for improved transportation corridor risk management. R.A. Kromer et al.

Characteristics and influence of brittle structures and fold geometry in the development of slope deformations in Turtle Mountain (AB, Canada). F. Humair et al.

Minor landslides and floods events affecting transportation network in Switzerland, preliminary results. J. Voumard et al.

Napoli1

Location of the Symposium.

Napoli2

During the lecture on “Human-Induced Landlisdes”.

Two more PhD students completed their theses at the Risk Analysis group

On last 8th July Friday, two PhD students (Raja Mastouri and Zar Chi Aye) from the Risk Analysis group have successfully finished their public defenses and obtained their doctoral degrees in Geosciences. Congratulations!

Raja Mastouri applied 3D seismic in combination with terrestrial laser-scanning and photogrammetry techiques to analyse faults and fractures in Eocene carbonate reservoirs, and to investigate basin tectonics in the Gulf of Gabes (Tunisia).

Zar Chi Aye developed a prototype web-based collaborative decision support platform for risk management of natural hazards. This platform aims to assist risk managers in analyzing impacts of natural hazards as well as authorities and decision makers in the decision-making process for selection of risk management measures in a collaborative and interactive manner.

If you are interested, check out the summary of their doctoral theses here and here, for more information.

Rapid Offline-Online Landslide Mapping tool (ROOl Map)

A prototype using open-source WebGIS technologies has been implemented to make data on hazard impacts, such as damaged infrastructure, landslides or flooding events available to authorities and the general public. This mobile application has been designed as a low-cost, rapid and participatory method for recording impacts from hazard events and includes geolocation (GPS data and Internet), visualize the map, drawing and adding a comment or feedback by public participation. It is possible to record such events and upload them through a server, where internet connections is available. This application can be accessed by a mobile phone (Android or iPhone) or a tablet as hybrid version for both offline and online versions.

Based on recent visit to Nepal, internet is available through mobile network however accessibility to the server was not easy. For this reason, an offline mobile application has been implemented to improve the lack of internet in rural area. This offline version has an interactive-offline map with satellites image added to improve the visibility and mapping landslides. After geolocation, the user can start mapping and save them into Geojson text file that can be easily uploaded to the server whenever internet is available. This prototype would be specifically targeted at conducting an assessment of landslides within a predetermined area to assess land use characteristics such as roads, forest area, rivers.

Following videos show the process of this offline-online landslide mapping tool. The area selected for this project is close to Pokhara, Nepal where so many landslides have been activated or reactivated after the last monsoon. More than 60 landslides during two days of field trips has been recorded.

 

Video 1: Offline Landslide Mapping tool: A case study from Nepal

Video 2: Online Landslide mapping tool: Uploading offline data into system

Video 3: Online Landslide Mapping Tool: Tutorial