Environmental seismology: What can we learn from ambient noise?

Abstract

Environmental seismology consists in studying the coupling between the solid Earth and the cryosphere, or the hydrosphere, the anthropospher. In practice, we monitor the modifications of the wave propagation due to environmental forcing such as temperature and hydrology, using ambient seismic noise that constitute a continuous, cheap and relatively reproducible source of vibrations. Recent developments in data processing [1], together with increasing computational power and sensor concentration have led to original observations that allow for this new field of seismology. In this paper, we will review how we can track and interpret tiny changes in the subsurface of the Earth related to external changes from modifications of the seismic wave propagation, with application to geomechanics, hydrology, and natural hazard [2]. We will demonstrate that, using ambient noise, we can track: thermal variations in the subsoil, in buildings or in rock columns with application to damage estimation; the temporal and spatial evolution of a water table; the evolution of the rigidity of the soil constituting a landslide, and especially the drop of rigidity preceding a failure event. [1] Shapiro, N. M., Campillo, M., 2004. Geophys. Res. Lett. 31, L7 614. [2] E. Larose et al.: J. Appl. Geophys. 116, 62-74 (2015).