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Session Overview
Session
Keynote - Michel Jaboyedoff. Toward the assessment of the rockfall sources hazard failure using 3D point clouds and remote sensing techniques
Time:
Wednesday, 17/July/2024:
9:00am - 10:00am

Location: Main auditorium - Salón de actos - Aulario II

Aulario II, Campus de la Universidad de Alicante. SIGUA Code: 0030PB010
Session Topics:
Keynotes

Presentations

Toward the assessment of the rockfall sources hazard failure using 3D point clouds and remote sensing techniques

Michel Jaboyedoff

University of Lausanne, Switzerland

Since the advent of LiDAR and structure from motion (SfM) techniques, GB-InSAR and thermal imaging, etc. the study of the hazard of failure of the rockfall sources has drastically changed. First, cloud points allow to characterize structures and assess the rockfall source volume distribution by periodic acquisitions, which is fundamental for rockfall hazard assessment. Several studies have shown that volume distributions follow power laws. These distributions are nowadays crucial for real rockfall hazard assessment. However, they have inherent limitations, such as time steps sampling, or fragmentation degree after failure. Such an approach provides for diffuse hazards, i.e., the exact locations of the sources are not known, but also to better characterize the rockfall activity of the different rock source types and structures. When the source is located, the temporal probability of failure must be evaluated. This means that state of stability or rock mass degradation must be assessed. Using remote sensing methods several promising research avenues exist. This can be performed using monitoring rock mass strength degradation via high-resolution 3D tracking of cyclic deformations with hysteresis by 3D point clouds or GB-InSAR. These deformations can result from factors like groundwater circulations, thermal cycles, earthquakes, rainfall, etc. The thermal imaging of shallow rock instability can provide the extend of rock bridges and can be coupled with deformation. Several attempts have been made to extract from 3D point cloud discontinuity set characteristics such as spacing and trace length distributions, but several drawbacks exist such as recognition of traces on point clouds without available surfaces or the true distribution of trace lengths. Nevertheless, more and more solutions are developed. The geological strength index (GSI) can be evaluated using remote sensing such as thermal imaging or discontinuity characterization by 3D data. The GSI can be used to estimate the power-law parameters. One of the key challenges to enhance rockfall sources hazard assessment, it's essential to better understand these processes and their interplay with physical and chemical weathering. Because the erosion of weak rocks, such as marls, may help to understand the thermal and rainfall effects on rock mass degradation. In conclusion, high resolution remote sensing data support the understanding of external forcing on rockfall activity, in particular characterizing volumes distributions and deformations.