Recent decades have seen significant advances in the experimental quantification and numerical modelling of how surface geology affects ground motion. These include efforts to use seismic ambient noise to derive specific site amplification characteristics and to better constrain subsurface structures.
Despite the development of several empirical recipes, there is currently no consensus on how to determine site amplification for real earthquakes based on ambient noise characteristics. In fact, there is still no clear evidence that this is even possible. This uncertainty is closely linked to the fundamental differences between the seismic wavefields of earthquakes and ambient noise.
It is therefore important to better understand a) the earthquake ground motion in local surface sedimentary and topographic structures, b) seismic ambient noise in these structures, and c) characteristics of seismic ambient noise that could suggest, identify or even quantify a potential effect of surface geology on earthquake ground motion.
Numerical modelling can very much help to understand both earthquake ground motion and seismic ambient noise. Whereas more modelling was focused on the earthquake ground motion, only relatively limited work has been done on the numerical modelling of ambient noise: at both low frequencies (microseisms) and high frequencies (microtremor). As a result, we still lack a clear understanding of what quantitative information can be reliably extracted from noise measurements, and what processing techniques are most appropriate. This is especially true for frequency-dependent amplification in the linear domain.
The session will thus welcome contributions on site response and/or use of seismic ambient noise for characterizing site response. All kinds of approaches can be considered: instrumental measurements with sparse or dense arrays, advanced processing, theoretical or numerical modelling of earthquake ground motion and/or seismic ambient noise. A special interest will be brought to contributions linking earthquake site effects and seismic ambient noise.
Studies may concern sites with various dimensionalities (1D, 2D, 3D, with or without material heterogeneities) and various underground and surface geometry (including topography). Examples of apparent inconsistencies between noise measurements and instrumental earthquake site response are also welcome to gather as complete as possible picture of the issues which are still ahead.