The mechanical behavior of Earth materials represents a unifying theme in both the occurrence and prediction of a wide range of natural hazards including landslides, earthquakes, volcanic eruptions and flank collapse, and sudden glacial acceleration (i.e., surging or complete detachment). We invite submissions that bring perspectives from laboratory, field, and/or numerical approaches to understand the role of rock, sediment, soil, ice, and magma rheology (as well as their mixtures).  This session will explore how knowledge of rheology can be used to constrain ambient in situ conditions (e.g. stress, fluid pressure, and subsurface heterogeneity) that set the stage for failure, as well the deformation processes and dynamics that underpin hazards.