Data for: Linear and nonlinear elastodynamic signatures of fractured rock in relation to fault characteristics inferred from in-situ synchrotron X-ray computed tomography

Stress wave-based imaging holds great promise for remotely and non-invasively monitoring the real-time evolution of subsurface fractures’ or faults’ physical characteristics and state across length scales of practical interest. Key fracture attributes – such as in-situ contact area, aperture, and pore volume – are critical for predicting the frictional and poromechanical behavior of fractured rock. In this study, we employ in-situ synchrotron X ray computed tomography (CT) and radiography to image fractured rock samples subjected to both static and dynamic stresses, while simultaneously recording their ultrasonic responses. We investigate the nonlinear elastic properties of stressed fractures and their connections to the evolving stress-controlled fracture geometry. Linear and nonlinear ultrasonic parameters are quantitatively related to calculated fracture characteristics – such as contact area, contact size distribution, aperture, and changes in aperture – directly recovered from X-ray images. Our results show that wave spectral properties reflect fracture aperture evolution, which is the first time this has been experimentally measured with in-situ X-ray imaging. We also find that ultrasonic transmission amplitude directly correlates with contact area, irrespective of contact distribution as previously thought. Moreover, we observe potential links between the ultrasonic nonlinearity parameter, β, and contact area and distribution. These findings are invaluable for interpreting seismic signatures of fractured rock and provide critical insights into inferring subsurface fracture characteristics from seismic data.