Slow dynamics under high confining pressure in saturated sandstone with pore pressure

Manuel Asnar , Christoph Sens-Schönfelder , Audrey Bonnelye, Marco Bohnhoff

Slow dynamics is a time-dependent, nonlinear elastic behavior occurring in a variety of consolidated or damaged materials, including rocks. The influence of relative humidity and confining pressure on slow dynamics has been studied, but not that of full saturation and effective pressure. We show that slow dynamics is occurring under high confining pressure in fluid-saturated sandstone, if the effective pressure is low enough. This suggests that effective pressure determines whether slow dynamics can be observed, explaining why field observations are possible not only near the surface but also in environments with high pore pressure such as fault zones or volcanoes.