Seismic Characterization of Landslides and the Emergence of Seismic Monitoring

After a short introduction on the main problems that need to be better understood in order to better model landslide dynamics, this contribution focuses on how geophysical methods and in particular seismic methods can help in better characterizing the geometry and heterogeneities of landslides. Indeed, these parameters constitute fundamental inputs that need to be precisely addressed before any numerical modelling attempt. We will notably show the sensitivity of shear wave velocity to the variation of shear strength in soft landslide. In a second part, a focus is done towards the emergence of seismic monitoring methods which are now used for different purposes. They include seismic activity assessment and characteristics (location, magnitude, classification), which permit to study the correlation of this activity with other observables (meteorological, displacements) in order to better understand hydro-mechanical coupling at a large scale on landslides. Seismic observatories also enable characterizing the dynamics properties of seismic site effects due to the presence of disturbed materials. Again, this property must be taken into account in any numerical attempt that aims at evaluating the potential sensitivity of the landslide stability to different earthquake scenario. Finally, the use of correlation of continuous ambient seismic noise recorded by at least two different sensors can permit to detect very weak shear wave velocity changes between these sensors. Strong variations of shear wave velocity might be a precursor to rupture.