Periodic Reporting for period 1 - SHEAR (the role of Stress History on the EARthquake potential of faults)
Reporting period: 2022-07-14 to 2024-07-13
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.
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.
Throughout the course of the project, the following key activities and scientific achievements have been accomplished:
1) Laboratory Simulations of Different Loading Paths: A series of laboratory experiments were conducted using state-of-the-art deformation apparatuses to simulate fault behavior under different loading path conditions. These experiments collected high-resolution mechanical and acoustic data to study how different stress histories (loading paths) affect fault stability and seismic slip potential. Additionally, the project fostered international collaborations, enhancing the scope of the research.
2) Hydro-mechanical Coupling Under Varying Permeabilities: Experiments revealed insights into how faults respond to changes in clamping pressure, particularly in response to fluid pressure drops, depending on their permeability. These findings are especially relevant to carbon dioxide storage and geothermal energy, where the management of induced seismicity is vital.
3) Fault Orientation and Precursory Seismicity: The project also explored how damage zones and fault orientation control the occurrence of seismic precursors under different loading paths. Well-oriented faults were found to exhibit more detectable seismic precursors than misoriented faults, which face different loading challenges.
4) Expansion of Expertise: The project provided the researcher with advanced training in fault mechanics, seismology, and experimental rock mechanics, enhancing their understanding of the complex interplay between stress history and fault slip behavior.
The dissemination and exploitation activities have been key to maximizing the scientific and societal impact of the research:
1) Scientific Dissemination: The project’s results were presented at major geoscience conferences, including the European Geosciences Union (EGU) and American Geophysical Union (AGU). Additionally, seminars and workshops were organized to share findings with the academic and industrial communities.
2) Public and Educational Outreach: Webinars were held to engage a broader audience, including students and the general public, to raise awareness about the project’s research and outcomes.
1) Laboratory Simulations of Different Loading Paths: A series of laboratory experiments were conducted using state-of-the-art deformation apparatuses to simulate fault behavior under different loading path conditions. These experiments collected high-resolution mechanical and acoustic data to study how different stress histories (loading paths) affect fault stability and seismic slip potential. Additionally, the project fostered international collaborations, enhancing the scope of the research.
2) Hydro-mechanical Coupling Under Varying Permeabilities: Experiments revealed insights into how faults respond to changes in clamping pressure, particularly in response to fluid pressure drops, depending on their permeability. These findings are especially relevant to carbon dioxide storage and geothermal energy, where the management of induced seismicity is vital.
3) Fault Orientation and Precursory Seismicity: The project also explored how damage zones and fault orientation control the occurrence of seismic precursors under different loading paths. Well-oriented faults were found to exhibit more detectable seismic precursors than misoriented faults, which face different loading challenges.
4) Expansion of Expertise: The project provided the researcher with advanced training in fault mechanics, seismology, and experimental rock mechanics, enhancing their understanding of the complex interplay between stress history and fault slip behavior.
The dissemination and exploitation activities have been key to maximizing the scientific and societal impact of the research:
1) Scientific Dissemination: The project’s results were presented at major geoscience conferences, including the European Geosciences Union (EGU) and American Geophysical Union (AGU). Additionally, seminars and workshops were organized to share findings with the academic and industrial communities.
2) Public and Educational Outreach: Webinars were held to engage a broader audience, including students and the general public, to raise awareness about the project’s research and outcomes.
The SHEAR project has produced several key results that push the boundaries of current knowledge in fault mechanics and earthquake prediction:
1) New Understanding of Fault Behavior Under Different Loading Paths: The research has demonstrated that fault orientation—which determines different loading paths—plays a significant role in the occurrence of seismic precursors. Well-oriented faults exhibit clear precursory signals before reactivation, while misoriented faults slip without detectable signals, challenging the predictability of such events.
2) Hydro-mechanical Coupling Insights: The project explored how permeability affects fault slip behavior. These findings have significant implications for carbon dioxide storage and geothermal energy industries, particularly in the management of induced seismicity and fluid injection processes.
Future steps may involve further demonstration of these findings, expanding the range of loading paths explored in the laboratory. Particular focus will be placed on understanding precursory seismic activity across different tectonic regimes and the hydro-mechanical coupling of fault zones.
1) New Understanding of Fault Behavior Under Different Loading Paths: The research has demonstrated that fault orientation—which determines different loading paths—plays a significant role in the occurrence of seismic precursors. Well-oriented faults exhibit clear precursory signals before reactivation, while misoriented faults slip without detectable signals, challenging the predictability of such events.
2) Hydro-mechanical Coupling Insights: The project explored how permeability affects fault slip behavior. These findings have significant implications for carbon dioxide storage and geothermal energy industries, particularly in the management of induced seismicity and fluid injection processes.
Future steps may involve further demonstration of these findings, expanding the range of loading paths explored in the laboratory. Particular focus will be placed on understanding precursory seismic activity across different tectonic regimes and the hydro-mechanical coupling of fault zones.