Recent laboratory experiments investigating the frictional properties of rock indicate that faults are profoundly weakened at dynamic sliding rates typical of earthquakes. Understanding the cause and extent of dynamic weakening is critical to advance predictive models for nucleation, rupture propagation, and energy radiation patterns of earthquake slip events that can help mitigate the hazards of earthquakes and tsunamis. At this time our ability to investigate dynamic weakening is severely limited because laboratory instruments capable of replicating the conditions of earthquake nucleation and rupture in the Earth do not exist. This project will design, construct, and commission an instrument that can simultaneously achieve the conditions of elevated confining pressure, pore fluid pressure and temperature, variable slip rates from Âµm/s to m/s, and shear displacements of at least several centimeters to systematically investigate slip instability in the Earth. The apparatus will employ a novel biaxial frame housing a pressure vessel to accommodate double-direct shear and triaxial shear configurations, and servo-hydraulic and pneumatic loading systems.
The instrument will 1) advance basic research in areas relevant to mitigating natural hazards associated with earthquakes, 2) provide a state-of-the-art laboratory facility for training the next generation of researchers through an integrated graduate education and research program in geophysical rock mechanics at Texas A&M University, and 3) provide new opportunities for education and outreach to students across the STEM fields, particularly undergraduate and graduate students in engineering and geoscience. With respect to this project, the principal investigators are committed to national and international research collaboration, shared use of the new apparatus and laboratory facilities, long-term maintenance of the equipment, and sustaining a research and education program that values diversity.