The lithosphere is constantly subject to stresses resulting from geodynamic processes, gravitational forces and anthropogenic activities. A thorough understanding of the stress state is crucial for a wide range of topics, from plate tectonics and geohazards to mass transport and engineering applications. Conventional and emerging applications such as geothermal energy, Carbon Capture and Storage (CCS), hydrogen or gas storage or disposal of nuclear waste are pivotal for a low-emission society, with their efficacy heavily reliant on knowledge of the stress state. However, the stress state remains difficult to measure, and our comprehension of stress magnitudes depends much on our ability to constrain them from observations, experiments and models.
Characterisation of stress state is challenging because stresses orientation and magnitude are variable (spatially and with depth) and sometimes are time-dependant. More importantly, in most cases we do not fully understand all the factors causing these variability. Fluids are known to reduce rock strength and trigger seismicity by reducing effective stresses and driving mineral reaction, but their exact role in driving mechanical instabilities needs to be better understood, also with respect to other processes like transformation-driven stress transfers.
The current state of stress is mainly assessed using seismic focal mechanisms, fault monitoring and slip inversion, borehole data, and methods such as hydraulic fracturing to determine the magnitude of the applied stress. However, the full stress tensor remains difficult to determine, and investigations typically cover specific spatial and/or temporal scales. Another limitation posed by current methods to stress magnitude estimation is their deterministic nature. In real-world scenarios, parameter uncertainties, such as variations in rock strength, play a crucial role. This necessitates the integration of uncertainty quantification techniques to deal with incomplete datasets.
To address these challenges, we must advance and develop concepts, experiments, measuring methods, data compilations, and models. In this session, we intend to bring together researchers from various fields. We seek contributions that advance (1) our ability to estimate the stress orientation and magnitude, (2) improve geomechanical modelling approaches, (3) our general understanding of the governing mechanics of seismotectonic processes, and (4) relevant case studies.