arXiv subjects

Pierre Bottelin

Publications and source records attributed to Pierre Bottelin.

3 recordsLinked to original sources

arXiv2026

Characterizing landslide dynamics from time-lapse time domain induced polarization and ground-based imaging: a case study of the MontGombert landslide (French, Alps)

Electrical resistivity tomography (ERT) is widely used to investigate landslide morphology and dynamics. Landslide behavior is strongly influenced by clay content, pore pressure, and the spatial distribution of permeability. However, conventional direct current (DC) resistivity methods have limited capacity to characterize permeability, as materials with low electrical resistivity may exhibit either high or low permeability depending on their clay content and the relative contributions of surface and electrolytic conduction. Induced polarization (IP) offers a valuable complementary approach for investigating the petrophysical properties of geological materials. Despite its potential, IP has been rarely applied to landslide studies and has not yet been widely used for landslide monitoring. This study investigates the added value of IP measurements alongside conventional DC resistivity for landslide characterization and monitoring. Three time-domain induced polarization (TDIP) surveys were conducted at different time steps on an active landslide in the French Alps. Time-lapse inversions of resistivity and chargeability were performed, and spectral IP parameters were derived using Debye decomposition. The results were then compared with surface displacement estimates obtained from optical image processing. The findings demonstrate that TDIP is particularly valuable for delineating unstable volumes within the landslide. The geophysical results show strong agreement with independent measurements from piezometers and inclinometers. Furthermore, applying an empirical relationship between IP parameters and permeability enables the spatial distribution of permeability within the landslide to be estimated, as well as its seasonal variations. Overall, this study highlights the potential of combining IP and DC resistivity measurements to improve the characterization of landslide properties and support the monitoring of their temporal evolution.

physics.geo-ph↗

arXiv2026

Mapping rockfall hazard and detecting precursory damage in rock slopes with passive seismic: Lessons from the La Praz case-study

Repeated passive seismic surveys were conducted over more than a decade on the unstable La Praz rock slope in Savoie, France, which involved an estimated rock volume of approximately 13,000--15,000 m${}^3$. The final survey took place two months before the complete collapse of the slope in August 2023. The amplitude of the Horizontal-to-Vertical Spectral Ratio at the peak frequency (*aHVSR(fp)*) was used to distinguish stable and unstable areas and identify fractures associated with significant mechanical decoupling. Rock compartments were also classified according to their rockfall hazard. The compartments most susceptible to failure exhibited the highest *aHVSR(fp)* values, ranging from 26 to 157, compared with values of 7.5--19 in intermediate-hazard areas and 2.7 in the adjacent stable rock mass. The main HVSR peak frequency (*fp*) exhibited distinct decreases of 15%, 14%, and 11% in three unstable rock compartments before the collapse. These reductions substantially exceeded the range of environmentally induced resonance-frequency fluctuations observed at the site and commonly reported in the literature as a limitation of this method. The frequency decreases were interpreted as indicators of progressive damage extending into the rock slope. Notably, these changes were detected exclusively in the three compartments identified as the most susceptible to failure, which also exhibited the highest *aHVSR(fp)* values. This study demonstrates, for the first time, the potential of passive seismic monitoring to reveal progressive in-depth damage within a complex, heterogeneous, and highly fractured rock slope. The findings highlight the value of combining HVSR amplitude and peak-frequency variations to characterize unstable rock compartments and identify potential precursors to catastrophic slope failure.

physics.geo-ph↗

arXiv2026

Environmental seismology: What can we learn on earth surface processes with ambient noise?

Environmental seismology investigates mechanical vibrations generated by external processes or influenced by phenomena originating outside the solid Earth. It encompasses interactions between the solid Earth and other environmental systems, including the cryosphere, hydrosphere, and anthroposphere, as well as the specific sources of seismic vibrations associated with these systems. This field also examines how environmental factors, such as temperature fluctuations and hydrological variations, affect seismic wave propagation. Recent advances in data-processing techniques, combined with increased computational capabilities and the growing density of seismic sensor networks, have enabled novel observations and contributed to the emergence of environmental seismology as a distinct research field. This article reviews how subtle changes in the Earth's subsurface can be detected and interpreted through variations in seismic wave propagation induced by external environmental processes, with applications to geomechanics, hydrology, and natural hazard assessment. In particular, we demonstrate how ambient seismic noise can be used to monitor: (1) thermal variations in the subsurface, within buildings, and in rock columns; (2) the temporal and spatial evolution of groundwater levels; and (3) changes in the rigidity of the material forming a landslide, with particular emphasis on the reduction in rigidity that may precede slope failure.

physics.geo-ph↗