Over the last decades, dramatic improvements in the quality and quantity of geophysical and geodetic observations revealed rich rheologic and brittle behavior of the Earth materials under the wide range of stress and temperature conditions. These observations exposed the applicability limits of the existing theories of deformation, and opened new exciting opportunities in the field of geological mechanics. The proposed research activities will focus on interdisciplinary studies of the rheologic and fracture properties of the Earth's lithosphere using natural and man-made sources of deformation. The lithosphere is believed to respond to tectonic and volcanic loads in a variety of ways, ranging from a predominantly elastic deformation to brittle failure, viscous creep, and plastic yielding. However, the bulk mechanical properties of rocks that govern the large-scale deformation are still poorly known. Detailed knowledge about the mechanisms of rock deformation is essential for understanding a number of fundamental geological and geophysical processes, such as the earthquake cycle, mountain building, rifting of the lithosphere, volcanic activity, etc. While significant insights into the constitutive properties of rocks have been obtained from laboratory experiments, extrapolations of the laboratory measurements to the crustal-scale deformation have proven to be difficult. The proposed research will take advantage of recent advances in (i) space-based geodetic observations of the Earth, (ii) available computational power, and (iii) modeling capabilities to address these problems. Robust inferences about the mechanisms of rock deformation are important from a societal perspective, as they directly bear on the issue of seismic and volcanic hazards in populated tectonically active areas.
