Experimental studies on slow slip, fast failure, and episodic slip modulated by fluid pressure: implications for landslides and earthquakes

Landslides and faults would slip in various slip patterns with an extensive velocity spectrum. The slow-moving landslides, catastrophic fast landslides, and intermittent-moving landslides share much similarity with some of the earthquake phenomena, such as the slow fault slip, fast earthquake, episodic slip. Moreover, both landslides and faults would be strongly controlled by their hydrogeology system and fluid pressure conditions. Herein, we conducted stress path- and fluid pressure-controlled triaxial shear experiments and ring-shear experiments on granular geomaterials. We reproduced diverse slip behaviors, including the slow slip, fast failure, episodic slip, under monotonic fluid overpressure and episodic fluid pressure within drained or undrained conditions. Our experiments suggest that the slip velocity might be controlled by stress drop and vice versa. The role of contraction/dilatation tendency, drained/undrained conditions, velocity-strengthening/weakening properties in determining slip pattern is systematically studied. And we adopted both active and passive seismic methods, such as seismic wave velocity and acoustic emission signal monitoring, to explore the failure precursors. Our studies could be valuable for understanding the slow to fast earthquake phenomena and providing an integrative view for multiple geohazards through linking landslides and earthquakes.