This PhD dissertation focuses on the seismic signatures of the role of fluids in the deformation mechanisms of fractured rocks in the upper crust, mainly faults and landslides. While it is generally admitted that fluids are a triggering mechanism for rupture in the cases of episodic and major climate forcing events on shallow landslides, their role in the destabilization of large volumes of rocks, associated to weak forcing, is less understood. Thus, it is primordial to acquire new synchronous data of fluid pressure/flow, deformation and induced seismicity in the field, under controlled conditions of the hydraulic loading, in order to better understand the relationship between seismic and hydromechanical processes involved in the nucleation of rock ruptures, in part associated to the reactivation of existing fractures. Motivated by the need for new observations, this PhD thesis concerns the interpretation of the induced seismicity within unsaturated zones of deep rocky slopes, during original and controlled hydraulic stimulation experiments (0.3 to 3.5 MPa and from 10 to 3000 seconds) of small areas of decameter size. These experiments consisted in triggering rock deformations which lead to the activation of rock sliding along pre-existing fractures where deformation/pressure measurements and seismic sensors were distributed. These experiments were carried out in the Low Noise Underground Laboratory (France), which allows the access to fault zones within a rocky slope (at 250 m depth) and enables accurate geophysical measurements in conditions of very low environmental noise.
