In this paper we document the first example-the southern Delaware Basin-where widespread induced triggered (as opposed to "driven") seismicity across a large area exhibits a maximum magnitude truncation. The most likely cause of this truncation is that although the shallow faults in this area are many km in length, they are structurally constrained and have limited down-dip widths, typically no more than approximately 1 km. Ruptures on faults of such limited width are not expected to attain high aspect ratios. As such, the ruptures on such faults would be limited to dimensions of roughly 1 km2, which corresponds to magnitudes which closely match the observed MMAX truncation. The M MAX truncation for induced earthquakes in the southern Delaware Basin has significant implications since it implies that down-dip fault widths may play an important role in constraining the maximum magnitudes of induced events.

Abstract Forecasting is an essential part of risk mitigation, where the mitigation efficacy depends strongly on the quality of forecasts. We explore the neural temporal point process as a deep learning framework to forecast induced earthquakes. We train our deep learning model using numerous enhanced geothermal systems and hydraulic fracturing test cases. We find that our model's performance is comparable to that of a modified Epidemic Type Aftershock Sequence; the “winning” model varies, depending on the test case in question. The addition of supplementary input data (e.g., seismic moment release, cumulative volume, injection pressure, hydraulic energy) tends to reduce model performance, as compared to simply using traditional metrics (i.e., magnitudes and injection rates). Our model's architecture allows for a flexible and data‐driven inference of the inter‐event time distribution and the injection forcing function. We find that the inter‐event time distribution is compatible with an Omori‐like decay of seismicity rates. On the other hand, our model does not recover a linear proportionality between injection and seismicity rates—instead preferring a simple on/off relationship. Finally, we discuss the statistical/physical implications of these results for and suggest future improvements. Overall, this model will likely be an important part of an ensemble of forecasting approaches that constrain seismicity risks.

The success of geological carbon storage (GCS) operations depends on the effective management of risks, such as induced seismicity. In this study, we consider prior assessments of induced seismicity risks to guide our Measurement, Monitoring, and Verification (MMV) program for a prospective CO2 injection test site near Tr & uuml;llikon, Switzerland. A diverse suite of geophysical analyses including fault identification, fault slip potential, fluid pressure modelling, seismic risk modelling, and traffic light design are synthesized into MMV performance targets, based on recent 'good practice' guidelines. These MMV performance targets are then used to guide our MMV optimization process. This optimization process indicates that installing seven new broadband stations would improve the magnitude-of-completeness from ML 0.9 to ML 0.0, while lateral and depth resolutions would be improved to 50-100 m (for a ML 1.0 earthquake). While these optimized designs are expected to meet our MMV performance targets, we also provide contingency plans in the case that our estimates are overly optimistic. This contingency largely considers the quantification of noise attenuation with depth, which we estimate to be between a 10-fold to 30-fold improvement, based on a temporary downhole fibre optic deployment. Overall, this study demonstrates how GCS risks can be embedded into MMV design; our workflow can thus serve as a template to guide future GCS MMV designs, long before CO2 injection operations commence.

Multi-fault earthquake cascades, which can lead to unexpectedly escalated seismic risks, are not rare in large induced earthquakes. In such cascades, what roles injected fluids can play besides initiating the first main event remains an intriguing, yet under-researched question. Here we report a notable case where a sequence of four moderate earthquakes (M4.0-M4.9) triggered by fluid injection struck within two days on a shallow conjugate fault system in the Changning shale gas field, southern Sichuan Basin, China. The cascade triggering process and the seismogenic fault system are investigated through mutually consistent observations, including well-located seismicity, robust focal mechanisms, high-resolution 3D seismic reflection imaging, surface deformation from InSAR, and insights from geomechanical modeling. The cascading rupture can be explained by Coulomb stress changes and pore pressure perturbations in combination. Our observations suggest that fluids could play three diverse roles in the cascading rupture across time scales from less than a day to a few months, which to our knowledge has not been reported before, including: 1) downward-migrated fluids from ongoing hydraulic-fracturing operations directly induced the first main event, 2) long-distance migrated fluids from an adjacent hydraulic fracturing operation six months prior may have prepared the cascade triggering of the second event by elevating pore pressure, and 3) from the rupture area of the second event the co- and post-seismic migrated fluids could have promoted the third event likely with a fault-valve process. We suggest cumulative seismic risks, in addition to the risk associated with maximum magnitudes, should be carefully considered for risk mitigation in subsurface fluid injections.

In 2022-2023, three local-magnitude (ML) 4.8-5.6 earthquakes shook the Peace River oilsands area of Alberta, Canada. Previous studies statistically linked the seismicity to nearby disposal activities but lacked in-depth investigation into triggering mechanisms, including subsurface fluid migration and earthquake interaction. Here, we identify the seismicity as a directional, cascading rupture process initiated by wastewater disposal and sustained by tectonic fault interplay. Our findings highlight the role of regional geologic framework, a combination of a capped fringing-reef formation and a truncated fault, in channeling injected fluids. Injection above this architecture was effectively isolated, whereas fluids entering the reef formation progressively destabilized the fault, culminating in the ML 5.6 event on 30 November 2022. This mainshock triggered a southeastward rupture cascade, including two ML 4.8+ events on 16 March 2023. Earthquake swarms were primarily nucleated by the nearest reef-targeted disposal well, with secondary contributions from wells located 20-35 km away.

Identifying the primary triggering factors that govern injection-induced seismicity is essential for reliable seismic-hazard assessment. Here, we present observations from 20 surface stations deployed at China's first enhanced geothermal system (EGS) project in the Gonghe Basin during hydraulic stimulation and circulation tests in 2021. Using a machine-learning workflow, we compiled a high-precision catalog of 7,346 events (M L -2.0-2.18) that reveals a donut-like seismicity distribution comprising four major clusters with variable faulting styles. Principal-stress modeling indicates profoundly weak faults with a low friction coefficient (mu similar to 0.23 with 95% confidence interval of 0.19-0.48), consistent with chlorite-rich gouges, and a subcritical stress state in which low-to-moderate fluid overpressure (similar to 0.8-34 MPa) is required to initiate seismic slip. We find that the seismicity distribution is controlled by scale-dependent factors: at the site-scale (i.e., within similar to 1 km of the wellheads), events localize on mapped natural faults, indicating shear reactivation of subcritically stressed, pre-existing structures rather than the creation of new tensile fractures; at the borehole-scale (i.e., within similar to 1-100 m of the borehole trajectories), the main seismogenic zone coincides with pronounced SHmax rotation, reflecting lithologic contrasts and localized fault-damage zones. Overall, our integrated analysis underscores the necessity of explicitly incorporating the low-friction mineral phases, and scale-dependent controls, that is, heterogeneities of stress and structures, into seismic hazard assessments for EGS projects.

Abstract The treatment of induced seismicity risk would benefit from a small, standardized injection test that probes the seismic response to fluid injection—to optimally improve earthquake forecasts before a larger injection commences. To accomplish this goal, we propose a “model differencing” framework: this framework optimizes injection protocols by maximizing forecast differences between three model paradigms (statistics‐based, physics‐based, and machine‐learning‐based). The resulting injection protocols exploits modeling assumptions, to maximize differences in predictions. These optimized protocols are two‐phased: first forcing one model to be relatively more productive and then flipping it to be relatively under productive in the second phase. These phases create forecast differences by exploiting differences in model assumptions. We synthesize these results into a prototype for the SFIT (Seismogenic Fault Injection Test). With further refinement, our SFIT prototype could develop into a standardized test for induced seismicity. We further discuss model differencing to construct testable hypotheses.

One major hurdle for understanding earthquake mechanics are observational limitations. Important phenomena like strain localisation, fault dilation, and fault healing are readily studied in rock mechanical laboratory experiments and with numerical models. At the scale of natural earthquakes, however, these phenomena are often unresolvable, even by state-of-the-art observatories. To overcome this limitation, we are currently building the Earthquake Physics Testbed at the Bedretto Underground Laboratory for Geosciences and Geoenergies (BedrettoLab), an experimental testbed where we can activate an extensively instrumented natural fault zone via hydraulic stimulation. The goal of the Fault Activation and Earthquake Rupture (FEAR) project is to induce earthquakes of up to Mw~1.0 on this exceptionally well characterised and instrumented fault zone. Here we summarize the main scientific goals and current FEAR project status, and present first results from conducted experiments. We discuss how this large-scale experimental approach may allow us to tackle both fundamental science as well as practical questions on earthquake physics, induced seismicity and seismic hazard.

Managing induced seismicity risk is needed to enable the widespread adoption of geothermal technologies, facilitating the transition towards a decarbonized energy sector. In April 2022, real-time monitoring and forecasting of induced seismicity were tested during a three-stage hydraulic stimulation in a deep granite heat reservoir at the Utah FORGE site. Here, we analyze the recorded seismicity through statistical inference, and investigate the possible fracturing mechanisms triggered by the injection operation. Our analysis indicates that seismicity is likely induced by opening of a tensile fracture. Through pseudo-prospective forecasting, we then replay the Stage 3 stimulation and related induced seismicity as if it were happening in real-time. We demonstrate that even if the physical processes are complex and likely difficult to disentangle using seismicity alone, physics-based seismicity rate forecasting models show promise for stable forecastability of seismicity induced during hydraulic stimulation. Our results pave the way for Advanced Traffic Light Protocols (ATLP) to become standard operational technology in the mitigation strategies of deep geothermal projects.

Constraining the maximum possible magnitude (MMAX) of an induced earthquake sequence is a challenging process with important implications for managing risks. CAP-tests are a suite of statistical tests that can infer, quantify, and select best-fitting MMAX models via an earthquake catalogue’s magnitudes. We use CAP-tests to discern between bound/unbound earthquake sequences at underground laboratories, where high-resolution and near-field geophysical observations are abundant. There, we find clear evidence for bound sequences, where magnitude growth was restricted during stimulation. Furthermore, bound sequences tend to be associated with stimulations that occurred within intact rock. On the other hand, unbound sequences tended to be associated with stimulations where hydraulic fractures interacted with relatively large pre-existing faults/fractures. We further examine bound sequences by fitting magnitude growth to a generalized family of MMAX functions. This process appears to be able to aggregate bound sequences into categories consistent with theoretical considerations (e.g., tectonic, tensile-crack, or shear-crack). These results provide a basis for validating and interpreting bound sequences in controlled experiments, which is important for extrapolating to larger-scale observations. Overall, CAP-tests appear to be a promising avenue for constraining MMAX from earthquake catalogue data.

Abstract Improving our understanding of induced and natural earthquakes benefits from controlled experiments in insitu laboratories. To investigate the processes during an Mw∼0 earthquake, we performed the “ Mzero ” experiments in a densely instrumented testbed of the Bedretto Underground Laboratory. These multi‐day hydraulic stimulation experiments went the opposite direction to typical induced seismicity research in that they were designed to enhance seismic rupture. In the first experiment, MzeroA, the rock mass was preconditioned by injecting water for 4 days at a pressure just below fracture reactivation pressure followed by a hydraulic stimulation above reactivation pressure. This strategy aimed at increasing the fractures area near critical stress conditions for shear failure, thus facilitating larger ruptures. During MzeroA, an event with Mw–0.54 was induced, followed by a distinct aftershock sequence. This event was one magnitude unit larger than any preceding event. In the second experiment, MzeroB, stimulation was initiated directly, without preconditioning. Compared to MzeroA, MzeroB exhibited higher seismicity rates, a larger seismicity cloud, and a pronounced migrating seismicity front. Combining seismological and hydromechanical observations, we discuss mechanisms that may have influenced the contrasting seismicity responses. In addition to fluid preconditiong, stress transfer from the Mw–0.54 mainshock, and natural seasonal pressure changes, may have contributed to modulating the seismogenic response. However, the relative importance of these processes remains uncertain given experimental limitations. Our results highlight both the potential and challenge of designing hydraulic stimulations to enhance or suppress seismic rupture, with implications for earthquake physics and induced seismicity.

Subsurface fluids are important to earthquake physics since they influence every phase of the earthquake cycle: from inducing earthquakes, generating slow slip, dynamically weakening a fault, to producing afterslip. Despite this prominent role, comparatively little thought has been directed toward intentionally controlling fault slip. I take the spring-slider as the simplest analogue for earthquake-like motion and train a deep reinforcement learning agent to design fluid injection that reins-in slip motion (i.e., controls slip velocity). These reining algorithms can mitigate stick-slip instability via a three-step injection policy. First, by injecting to induce slip nucleation; second, by harnessed withdrawal that governs slip speed; third, by injection-driven steady-state sliding. These numerical simulations are supported by theoretical derivations that show fault slip acceleration can be reined-in by balancing pressurization rate with state evolution changes. I discuss the relevance to prior studies, robustness of the algorithms, and discuss potential limitations/solutions to scaled-up problems. Together, these results suggest that spring-sliders could be tamed with a carefully designed injection policy.

In April 2022, a three-stage hydraulic stimulation was performed in a deep granite heat reservoir of low permeability at the Utah Frontier Observatory for Research in Geothermal Energy (FORGE). During the stimulation, around 1600 m3 pressurized fluids were injected into the target reservoir of ~2.4 km depth aiming at creating fracture networks and improving reservoir permeability for heat extraction. Microseismic monitoring is required to assess the stimulation efficiency and manage the induced earthquake risk during the stimulation. We perform near-real-time microseismic monitoring in a playback mode at the third stage of the stimulation where three deep monitoring boreholes equipped with three-component geophone chains were in operation. We apply machine learning (ML) techniques in combination with waveform back projection approaches to automate the microseismic event detection, increase microseismic event location accuracy, and promote the real-time capability of the monitoring workflow. Due to a lack of labeled datasets for model training or transfer learning, we devise a rescaling technique to tune the continuous microseismic recordings of high sampling rates that enables the application of existing ML models pre-trained on tectonic earthquakes. Our benchmark tests show that the proposed rescaling approach achieves high precision and accuracy in detecting microseismic events and picking their phase arrivals.With the proposed workflow, we compiled a high-resolution microseismic catalog containing around 36, 000 microseismic events with magnitudes of –3.0 to 0.5. Detected events are relocated using a double-difference relocation method and waveform cross-correlation-based arrivaltime refinement. We cluster the detected microseismic events according to their spatial distributions and identify the dominant stimulated fracture planes with principle component analysis of the different event clusters. The spatial distribution of the detected events nicely depicts the stimulated fracture networks which can be used to design the trajectory of the future production well. We analyze the spatio-temporal evolution of the induced microseismic events during and after the stimulation to illuminate the rupturing mechanisms responsible for the induced fracture networks. Induced microseismic events are analyzed together with the injection data to quantify the induced earthquake hazard and the hydraulic stimulation efficiency. The proposed microseismic monitoring workflow and the corresponding analysis provide more insights into the fracturing dynamics and the potential induced earthquake hazard in the Utah FORGE geothermal site, and would benefit the operation of other enhanced geothermal systems.

The world’s energy supply depends critically on hydraulic fracturing (HF) to access otherwise uneconomical resources. Unfortunately, HF also has the potential to induce larger earthquakes – with some projects being prematurely terminated because of perceived earthquake risks. To de-risk HF, we use a suite of statistical tests to discern if some physical process has restricted the growth of earthquake magnitudes. We show that all stage stimulations at both UK PNR-1z and Helsinki St1 indicate bound fracture growth, implying a more controllable operation. Contrastingly, stimulations at Utah FORGE and UK PNR-2 sequentially transitioned into unbound fault reactivation. The problematic stages (that ultimately led to the termination of PNR-2) are clearly distinguishable. We postulate that our research can discriminate fracture stimulation from fault reactivation, contributing to the de-risking of HF operations worldwide. Our statistical tests provide a framework for model falsification, which can guide physical insights into the bounding processes. A newly developed statistical approach using three distinct tests, termed CAP-tests, can discern cases of bound earthquake magnitude growth during hydraulic fracturing stage stimulations and could be used to de-risk future operations.

From 23 November 2022 to 30 November 2022, a sequence of earthquakes with a peak magnitude of ML 5.6 occurred similar to 46 km away from Peace River-a vibrant rural community in Alberta, Canada. Broadly felt by residents throughout central Alberta, the ML 5.6 earthquake on 30 November 2022 registers as the second-largest earthquake ever reported in the Western Canada Sedimentary basin and possibly the largest Canadian earthquake induced by human activities. On 6 December 2022, 1 week after the mainshock, the University of Alberta and Alberta Geological Survey jointly installed a circular array of nodal geophones surrounding the seismogenic zone. Over the next 4 months, this quick-response array (nicknamed "Peace River Induced Seismic Monitoring" array, for short PRISM) operated at temperatures as low as -30 degrees C and substantially bolstered the seismic data coverage in this previously under- sampled region. Our preliminary array data analysis has detected more than 2000 earthquakes with magnitudes ranging from -1.9 to 5.0 since the initial outbreak in late 2022. Investigations based on earthquake location, focal mechanism, and magnitude jointly reveal distinct earthquake clusters distributed along pre-existing faults from earlier tectonic events. The data recovered from this array offer unique and vital constraints on the tectonic histories and seismic risks of the Peace River region.

Consolidating state-of-the-art science into guidelines provides a path forward for managing induced seismicity risks and highlights avenues for future research.

Activities related to energy production have been linked with felt (and in some cases damaging) earthquakes. Notable examples include hydraulic fracturing, wastewater disposal, geothermal systems, coal mining, carbon storage and hydropower dams. As the demand for energy continues to grow, new frontiers in energy exploration will emerge - some with the potential for induced seismicity. Thus, there is a clear need for a source-agnostic seismic risk protocol that can be applied to any activity or region. This study outlines one such implementation that uses scenario earthquakes to produce a priori risk thresholds that can be referenced against current seismicity levels on an ongoing basis. Our framework is designed to inform regulatory decisions by considering the consequences of earthquake scenarios on the population and the built environment, together with simplified forecasts of the next largest magnitude. The proposed framework can tackle both the screening process needed for permitting purposes and serve as a risk management plan during operations.

Successful carbon injection operations depend critically on the management of risks, like induced seismicity. Here, we consider the bowtie risk management framework to organize pre-screening efforts around a prospective CO2 injection operation near Trullikon, Switzerland. First, potential barriers/threats are appraised via a literature review of the regional seismotectonics, hydrogeology, and nearby induced seismicity cases - which suggests a natural propensity for earthquakes because of the proximity to the Neuhausen Fault and a lack of effective underlying hydrogeological barriers. Next, we engineer barriers to fault reactivation by quantifying the fault slip potential. The closest (similar to 700 m) and most susceptible (similar to 3.0 km) portions of the Neuhausen Fault would require similar to 1.7 MPa and similar to 0.47 MPa for reactivation, respectively. The most susceptible (unknown) faults are normal slip (168. strike) that require similar to 0.23 MPa for reactivation. Injection simulations indicate pressure changes on Neuhausen Fault segments of 0.01-0.05 MPa - values that are 1-2 orders-of-magnitude smaller than those needed for fault reactivation. These engineered barriers limit the potential for fault reactivation. However, if these barriers prove totally ineffective, we have also designed a traffic light protocol as a reactive mitigation measure. Forecast estimates of nuisance, damage, and fatalities are used to infer the last-possible stopping-point based on a comparison with operation-ending risks encountered at Basel and St. Gallen. This indicates a red- and yellow-lights of MW similar to 2.0 and MW similar to 0.0, respectively. We synthesize these disparate pre-screening analyses to recommend performance targets for real-time seismic monitoring. Future CO2 operations will likely find our approach helpful for designing effective risk management.

Open AccessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Paluszny Adriana, Schultz Ryan and Zimmermann Günter 2024Induced seismicity in coupled subsurface systemsPhil. Trans. R. Soc. A.38220230193http://doi.org/10.1098/rsta.2023.0193SectionOpen AccessPrefaceInduced seismicity in coupled subsurface systems Adriana Paluszny Adriana Paluszny Imperial College London, London, UK [email protected] Contribution: Writing – original draft, Writing – review and editing Google Scholar Find this author on PubMed Search for more papers by this author , Ryan Schultz Ryan Schultz Swiss Seismological Service, ETH Zürich, Zürich, Switzerland Contribution: Writing – original draft, Writing – review and editing Google Scholar Find this author on PubMed Search for more papers by this author and Günter Zimmermann Günter Zimmermann Helmholtz Centre Potsdam GFZ German Research Centre For Geosciences, Potsdam, Germany Contribution: Writing – original draft, Writing – review and editing Google Scholar Find this author on PubMed Search for more papers by this author Adriana Paluszny Adriana Paluszny Imperial College London, London, UK [email protected] Contribution: Writing – original draft, Writing – review and editing Google Scholar Find this author on PubMed , Ryan Schultz Ryan Schultz Swiss Seismological Service, ETH Zürich, Zürich, Switzerland Contribution: Writing – original draft, Writing – review and editing Google Scholar Find this author on PubMed and Günter Zimmermann Günter Zimmermann Helmholtz Centre Potsdam GFZ German Research Centre For Geosciences, Potsdam, Germany Contribution: Writing – original draft, Writing – review and editing Google Scholar Find this author on PubMed Published:01 July 2024https://doi.org/10.1098/rsta.2023.0193Induced seismicity is the anthropogenic generation of tremors and seismic events that locally alter the state of subsurface stresses. The occurrence of induced seismicity during the deployment of subsurface technologies can cause projects to be arrested, as was the recent case in the United Kingdom during shale gas development and has been the case in many other locations worldwide, affecting the development of important green transition and energy security technologies that are being developed.Subsurface renewable energy technologies, such as carbon storage, geothermal energy extraction, hydrogen storage and compressed-air energy storage, are at the heart of the large-scale decarbonization of society and the sustainable development of an energy-secure future. All these technologies, which interact with the subsurface, have the potential to induce earthquakes, affecting the societal acceptance and financial viability of these projects at a large scale. There is currently a worldwide race to understand the controlling mechanisms of induced seismicity and how it depends not only on injection parameters and in situ stresses, but how it is also affected by rock and fluid properties and shifts to these properties, owing to natural spatial variations and temporally evolving geomechanical changes to the properties of the pre-existing discontinuities such as fractures and faults.Subsurface operations, such as carbon sequestration, can leverage the pore space in rock formations buried at depth to provide final containment of fluids over thousands of years and at large scale. The variability of the subsurface also supports the storage of fluids over short periods of time (months to years), such as in the case of hydrogen, compressed air storage and thermal energy storage, which have the potential to store surplus renewable energy seasonally, to balance consumption and production rates of renewable energy throughout the year. These technologies rely on the injection, storage and withdrawal of fluids into the subsurface and vary greatly across temporal and spatial scales. However, injection into the subsurface is known to perturb the mechanical state of equilibrium of faults, which can lead to slip, potentially causing induced seismicity. This seismicity can be felt at the surface and is largely dependent on the magnitude of the displacement, the depth of the event and the characteristics of the rock and soil that lie over the fault that has been reactivated.Induced seismicity has dramatically increased over the past 10 years, owing to the extensive hydraulic fracturing operations conducted worldwide, contributing to the negative social perception of the industry and leading to distinct regulatory dichotomies in the manner of how induced seismicity is managed. For example, some induced seismicity cases have caused economic/human losses through ground-shaking hazards; in other extreme cases, moratoriums on resource development have been emplaced owing to social concerns about these risks. Thus, there is a need to effectively manage these risks to avoid either type of loss. Even though there have been conserted efforts to minimize and prevent such occurrences in a systematic manner, induced seismicity is still a prevalent subsurface response to injection throughout the world, leading also to increased financial risk of subsurface technologies vital to large-scale decarbonization and sustainable energy storage. For many developing green technologies, proper management of induced seismicity will be a critical issue towards influencing public perception and promoting wide adoption.In the context of the green transition, rock properties, fluid density, cyclic injection and spatial in situ heterogeneities have become important foci of research exploring the fundamental controlling mechanisms of induced seismicity. There are ongoing efforts to understand the hydromechanical factors that affect induced seismicity, with the objective of developing new effective strategies to minimize the effects felt on the surface and to de-risk future subsurface operations. This issue aims to capture the state-of-the-art and novel research in this area, as of early 2024, to provide important lessons learned to directly support challenges faced by green-transition technologies.This issue presents a comprehensive exploration of fluid-induced seismicity across various energy production and storage technologies. The articles used a diverse range of methodologies, including numerical simulations, laboratory experiments, statistical analysis and seismic monitoring, to investigate induced seismicity. Across the papers, there is a shared focus on understanding the interplay between fluid injection, fault behaviour and subsurface structures. These diverse approaches enable a comprehensive exploration of fluid-induced seismicity across various geological settings and energy production technologies and contribute to our understanding of induced seismicity mechanisms, offering valuable insights for the mitigation of seismic hazards.Esmaeilzadeh et al. [1] investigated fluid-induced seismicity associated with sealing faults in the Triassic Montney Formation in Western Canada. The study reveals a significant spatial correlation between induced seismicity and high lateral gradients in pore pressure, indicating the importance of sealing faults in understanding induced seismic risk. Analysis of hydraulic fracturing operations near a 4.5 ML earthquake epicentre shows a large lateral pressure gradient, suggesting the potential for sealing faults to increase seismic hazard.Zhang et al. [2] investigated fluid-induced seismicity in enhanced geothermal systems by comparing direct and indirect fluid injection into faults in granite rock samples. Results show that injecting fluid adjacent to a fault, as well as directly into it, can induce seismic hazards owing to high fluid pressure creating new fractures. Identifying pre-existing faults is crucial to mitigate seismic risks during enhanced geothermal systems operations, requiring immediate action if faults are detected during hydraulic stimulation.Dang-Trung et al. [3] combined a multi-point flux approximation of flow with a contact mechanics approach, using a dual-mesh discretization, to show fracture propagation in two dimensions during injection near a fault in the context of geothermal reservoirs.Verdon et al. [4] investigated the dynamics of induced seismicity from long-term fluid injection across 20 case studies. Using the seismogenic index and seismic efficiency, they analysed seismicity rates against injection rates. Cumulative values steeply rise within one to three years of injection initiation, stabilizing thereafter. Time-windowed values peak within 25–35% of the sequence, then decline. This pattern reflects early high pore pressure changes diminishing over time. Models based on the seismogenic index and seismic efficiency show significant correlations between observed and predicted magnitudes, providing scientific evidence that understanding seismicity rate variations aids in calibrating site-specific pore pressure models for more accurate hazard forecasting and mitigation strategies.Boyet et al. [5] studied induced seismicity challenges in enhanced geothermal systems by combining a hydro-mechanical model with a seismicity rate model, to forecast mainshocks and aftershocks induced by fluid injection. Analysing Basel enhanced geothermal systems data, constant injection emerges as the most efficient strategy, enhancing fault permeability with limited post-injection seismicity. The hybrid model offers a versatile approach adaptable to various injection protocols, aiding safe enhanced geothermal system development.Schultz's [6] study presents a suite of statistical tools to infer maximum earthquake magnitudes from seismic catalogues. Through hypothesis testing, maximum likelihood estimation and ensemble weighting, these tools analyse induced seismicity data from various sources, revealing no evidence of volume-based influences restricting earthquake magnitude growth. Instead, an unbounded magnitude distribution adequately explains all cases tested. This suggests that induced earthquake hazards should be treated as unbounded, affecting hazard mitigation strategies. The developed tools offer a crucial means of understanding earthquakes and managing associated risks, with potential implications for future hazard mitigation efforts.Langenbruch's [7] study investigates the factors influencing maximum magnitudes of induced earthquakes, focusing on pressure diffusion in the Earth's crust. Analysing global energy project data, they correlated maximum magnitudes with pressure diffusion length, noting increasing nucleation potential over time. The nucleation potential for larger earthquakes increases over time owing to diffusion-controlled fault growth. Their model aligns with observations and suggests maximum magnitudes can surpass expectations based on fluid volume alone. The work provides evidence that the identification of larger-scale, pre-existing and critically stressed faults is instrumental to understand and mitigate induced seismic hazards.Dunham [8] extended models of fluid-driven fault slip by incorporating permeability enhancement and dilatancy effects that may occur during deformation. Dunham proposed that permeability enhancement and dilatancy, occurring instantaneously upon fault slip, can significantly influence the dynamics of fluid-driven shear fractures in low-permeability rocks, offering new insights into potential underlying mechanisms of fluid-driven fracture growth in understressed conditions.Wang et al. [9] investigated seismic activity induced by fluid injection in the Raton Basin, focusing on the interaction between seismic sources and subsurface structures. Through seismic monitoring and receiver function analysis, active fault segments and spatiotemporal patterns are revealed. Complex fault clusters near injection wells contrast with simpler structures farther away, while abrupt structural transitions coincide with seismic activity. The research underscores the significance of structural heterogeneities in influencing induced seismicity, with findings suggesting that fluid connectivity between injection depths and basement faults plays a crucial role.Burtonshaw et al. [10] investigated the effects of reservoir mechanical properties on induced seismicity during subsurface hydrogen storage. Through numerical simulations, this study assesses how variations in mechanical properties, such as Young's modulus, Poisson's ratio and Biot coefficient, affect fault slip in a porous depleted subsurface reservoir. The study finds that high Young's modulus (greater than 40 GPa), Poisson's ratio (greater than 0.30) and Biot coefficient (greater than 0.65) are preferable for minimizing seismic risk during low-density gas storage, such as hydrogen. Conversely, lower values of these properties increase the potential for induced seismic events at high injection rates, highlighting the need for careful selection of storage sites with suitable mechanical properties.These findings collectively contribute to evidence-based policymaking and regulatory processes, promoting the development of large-scale renewable energy, energy storage and decarbonization technologies reliant on sustainable subsurface operations.This issue is aimed at the wider academic community, regulators and government agencies seeking to support industry growth through evidence-based policies. It focuses on quantifying induced seismicity with physics-based evidence, which is required to maintain the framework of sustainable subsurface development. Our special issue is aimed at addressing key aspects such as financial investment risk, social perception and sustainable energy security. In particular, the UK government may need to consider adjustments to the traffic light system, which currently targets induced seismicity related to shale gas extraction. As green energy subsurface industries evolve, this system will probably require re-evaluation to accommodate the flexibility necessary for the development and refinement of storage mechanisms. This issue aims to highlight crucial new findings to better support this regulatory process, particularly in fostering the development of renewable energy and decarbonization technologies that depend on the subsurface for fluid storage, withdrawal or injection.We hope the articles in this volume illustrate both the achievements and challenges in the dynamic, multidisciplinary field of induced seismicity management. Especially as this field undergoes an exciting and rapid evolution, ultimately contributing to sustainable energy solutions and the advancement of our civilization. Data accessibility This article has no additional data. Declaration of AI use We have not used AI-assisted technologies in creating this article. Authors' contributions A.P.: writing—original draft, writing—review and editing. R.S.: writing—original draft, writing—review and editing. G.Z.: writing—original draft, writing—review and editing. All authors gave final approval for publication and agreed to be held accountable for the work performed therein. Conflict of interest declaration This theme issue was put together by the Guest Editor team under supervision from the journal's Editorial staff, following the Royal Society's ethical codes and best-practice guidelines. The Guest Editor team invited contributions and handled the review process. Individual Guest Editors were not involved in assessing papers where they had a personal, professional or financial conflict of interest with the authors or the research described. Independent reviewers assessed all papers. Invitation to contribute did not guarantee inclusion. Funding The authors thank the UK Natural Environment Research Council (NERC) for funding SeisGreen Project (Grant No. NE/W009293/1) which supported this work. The authors also thank the Royal Society UK for supporting this work, through fellowship URF\R\221050, awarded to Adriana Paluszny. Footnotes One contribution of 11 to a theme issue 'Induced seismicity in coupled subsurface systems'. © 2024, The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. References1. Esmaeilzadeh Z, Eaton DW, Hosseini N, Zeinabady D . 2024 Sealing faults and fluid-induced seismicity. Phil. Trans. R. Soc. A 382 , 20230418. (doi:10.1098/rsta.2023.0418) Link, Google Scholar2. 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(doi:10.1098/rsta.2023.0187) Abstract, Google Scholar Next Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetails This Issue09 August 2024Volume 382Issue 2276Theme issue 'Induced seismicity in coupled subsurface systems' compiled and edited by Dr Adriana Paluszny, Dr Ryan Schultz and Prof. Günter Zimmermann Article InformationDOI:https://doi.org/10.1098/rsta.2023.0193PubMed:38945165Published by:Royal SocietyPrint ISSN:1364-503XOnline ISSN:1471-2962History: Manuscript received20/05/2024Manuscript accepted20/05/2024Published online01/07/2024 License:© 2024, The Authors.Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. Citations and impact Keywordsseismicityinduced seismicityearthquakesgeomechanicsseismology Subjectsgeologygeophysicsplate tectonics