Solid as they are, rocks are not static materials with constant properties. Even small loads are enough to alter their mechanical properties; their reaction to being deformed is a loss of stiffness. Rocks which have been damaged in such a way are then less able to withstand loads, such as gravity or tectonic stresses. This phenomenon is therefore of relevance for understanding the occurrence of material failure, as in landslides or earthquakes.
Why seismic waves are slower shortly after an earthquake
