Earthquakes are sudden, unpredictable events that can cause severe damage and loss of life. Despite these challenges, our ability to predict them remains limited because we do not fully understand the physical processes that control when and how faults—fractures in the Earth's crust—reactivate. Fault reactivation occurs when stress builds up and is then suddenly released. Many laboratory studies have focused on faults that experience constant clamping pressure (normal stress), but in reality, many faults experience changes in this pressure over time. This is true for both natural seismicity and cases where human activities, such as fluid injections for geothermal energy production or carbon dioxide storage, are involved. In these scenarios, fluid pressure changes in the fault zone result in variations in clamping pressure. The way this clamping pressure evolves over time is called the loading path, which reflects the fault’s stress history.
The SHEAR project investigates how evolving loading paths—where clamping pressure changes over time—affect fault behavior and the occurrence of earthquakes. By conducting laboratory experiments simulating real-world fault conditions, the project aims to fill a critical gap in our understanding of fault mechanics. In the long term, this research could contribute to improved earthquake forecasting and seismic risk management, particularly in industries where human-induced seismicity is a concern.
The SHEAR project has successfully advanced our understanding of the role of the loading path in earthquake mechanics. The project’s conclusions demonstrate that the loading path influences precursory seismic activity, and that fluid pressure changes impact fault stability. Laboratory experiments have provided valuable insights into the mechanical and hydraulic properties of faults under different stress histories, contributing to both natural and induced seismicity research. Key conclusions include the finding that well-oriented faults exhibit more detectable seismic precursors than misoriented faults, due to the differences in the loading paths they undergo. Additionally, the project’s research on fault hydro-mechanical coupling under varying permeabilities has potential applications in carbon dioxide storage.
The project's innovative approach has contributed to setting new standards in earthquake research, and SHEAR's results are expected to play a key role in shaping future research lines.
