Добірка наукової літератури з теми "Seismicity triggering mechanism"

Deep earthquakes within subducting tectonic plates (slabs) are enigmatic because they appear similar to shallow earthquakes but must occur by a different mechanism. Previous attempts to explain the depth distribution of deep earthquakes in terms of the temperature at which possible triggering mechanisms are viable, fail to explain the spatial variability in seismicity. In addition to thermal constraints, proposed failure mechanisms for deep earthquakes all require that sufficient strain accumulates in the slab at a relatively high stress. Here, I show that simulations of subduction with nonlinear rheology and compositionally dependent phase transitions exhibit strongly variable strain rates in space and time, which is similar to observed seismicity. Therefore, in addition to temperature, variations in strain rate may explain why there are large gaps in deep seismicity (low strain rate), and variable peaks in seismicity (bending regions), and, possibly, why there is an abrupt cessation of seismicity below 660 km.

Abstract A pressure wave, initiated by water loading and propagating downward through subsurface water contained in fractures, has been hypothesized as a mechanism for triggering earthquakes along pre-existing faults at depths up to 15–20 km. Such a triggering wave might evidence itself by a coincident wave of descending seismicity. In the New Madrid region, seismicity has been reported to correlate with river stage, but usually with a lag of one to several months. River stage data from New Madrid and earthquake data from the St. Louis University’s microseismic network were examined for evidence of a time-lag in seismic activity with depth during the interval from Jan. 1, 1978, to May 31, 1987. The earthquake data include only events for which computed depths were available. The earthquakes were sorted by focal depth into two subsets of 3 km and 4 km thick layers, respectively. Earthquake data, represented by both number of events and strain factor [energy release], and river stage data were averaged over monthly intervals. Cross correlations were computed between stage and each layer. In addition, the earthquake sequences for each layer were cross correlated with those of the next layer. No evidence for a seismicity wave was found.

Abstract Following reservoir impoundment, stress changes occur due to elastic response and changes in pore pressure due to drained and undrained responses of the substratum. Elastic response may stabilize or destabilize the reservoir environment, depending on the nature of pre-existing stress field. However, the increase in pore pressure always leads to weakening of the rocks, facilitating the onset of seismicity. In most reservoirs, we usually observe the coupled poroelastic effect, and it is usually difficult to isolate individual contributions. Due to the availability of detailed seismicity and geological and in situ stress data at Monticello Reservoir, it was possible to study various factors that control the mechanism of reservoir-induced seismicity. Our results suggest that, during the filling period, the instability resulted from elastic, undrained, and possibly onset of drained response. Subsequently, the seismicity showed a more consistent pattern associated with diffusion of pore pressure.

We investigate two approaches for estimating formation permeability based on microseismic data. The two approaches differ in terms of the mechanism that triggers the seismicity: pore-pressure triggering mechanism and the so-called seepage-force (or effective stress) triggering mechanism. Based on microseismic data from a hydraulic fracture experiment using water and supercritical CO2 injection, we estimate permeability using the two different approaches. The microseismic data comes from two hydraulic stimulation treatments that were performed on two formation intervals having similar geological, geomechanical, and in situ stress conditions, yet different injection fluid was used. Both approaches (pore-pressure triggering, and the seepage-force triggering) provide estimates of permeability within the same order of magnitude. However, the seepage-force mechanism (i.e., effective stress perturbation) provides more consistent estimates of permeability between the two different injection fluids. The results show that permeability estimates using microseismic monitoring have strong potential to constrain formation permeability limitations for large-scale CO2 injection.

An elastic block lattice model is proposed to simulate the spatio-temporal seismicity and stress patterns in the Earth's brittle crust. The famous Gutenberg-Richter magnitude-frequency law in seismology is reproduced. The synthetic catalogs generated by this model are analyzed by using a linked stress release model, which incorporates the stress transfer and spatial interactions. The results highlight the triggering mechanism of earthquake occurrence and the evidence that the crust may lie in a near-critical or self-organized critical state due to the long-range spatial interaction of elastic stress. The spatio-temporal complexity of seismicity is closely related to both nonlinear dynamics of faults and heterogeneities in a seismic region.

Abstract Long-term and large-scale observations of dynamic earthquake triggering are urgently needed to understand the mechanism of earthquake interaction and assess seismic hazards. We developed a robust Python package termed DynTriPy to automatically detect dynamic triggering signals by distinguishing anomalous seismicity after the arrival of remote earthquakes. This package is an efficient implementation of the high-frequency power integral ratio algorithm, which is suitable for processing big data independent of earthquake catalogs or subjective judgments and can suppress the influence of noise and variations in the background seismicity. Finally, a confidence level of dynamic triggering (0–1) is statistically yielded. DynTriPy is designed to process data from multiple stations in parallel, taking advantage of rapidly expanding seismic arrays to monitor triggering on a global scale. Various data formats are supported, such as Seismic Analysis Code, mini Standard for Exchange of Earthquake Data (miniSEED), and SEED. To tune parameters more conveniently, we build a function to generate a database that stores power integrals in different time and frequency segments. All calculation functions possess a high-level parallel architecture, thoroughly capitalizing on available computational resources. We output and store the results of each function for continuous operation in the event of an unexpected interruption. The deployment of DynTriPy to data centers for real-time monitoring and investigating the sudden activation of any signal within a certain frequency scope has broad application prospects.

Delineation of physical factors that contribute to earthquake triggering is a challenging issue in seismology. We analyze hydrological modulation of seismicity in Taiwan using groundwater level data and GNSS time series. In western Taiwan, the seismicity rate reaches peak levels in February to April and drops to its lowest values in July to September, exhibiting a direct correlation with annual water unloading. The elastic hydrological load cycle may be the primary driving mechanism for the observed synchronized modulation of earthquakes, as also evidenced by deep earthquakes in eastern Taiwan. However, shallow earthquakes in eastern Taiwan (<18 km) are anticorrelated with water unloading, which is not well explained by either hydrological loading, fluid transport, or pore pressure changes and suggests other time-dependent processes. The moderate correlation between stacked monthly trends of large historic earthquakes and present-day seismicity implies a modestly higher seismic hazard during the time of low annual hydrological loading.

Using data on the seismicity of the Khibiny Mountains, it was shown that the distances from seismic events triggered by an earlier seismic event to their triggers obey a power-law distribution with a parameter independent of the magnitude of the trigger event. It was previously shown by Felzer & Brodsky [2006], Richards-Dinger et al. [2010] that the same distribution is appropriate for tectonic seismicity. Additionally, in the present paper, it was shown that in the Khibiny Mountains, the distribution of distances from seismic events to triggering explosions is also power-law. Thus, the power-law character of the spatial distribution of post-seismic activity takes place both for tectonic and mining-induced seismicity. The same type of distribution for postseismic and post blasting activities in the Khibiny Mountains gives a reason to suppose that the spatial distribution is determined by the features of the rock and does not depend on the mechanism of its perturbation (seismic event or explosion). The use of these features and the previously established laws of earthquake productivity verified for mining-induced seismicity, and seismic productivity of explosions, allows evaluating the zone where repeated events are expected with a given probability.

We present a model describing the seismicity rate of fluid injection-induced seismicity. We put the focus on seismicity induced after termination of fluid injections. Here, our primary objective is the identification of parameters controlling the decay rate of seismicity. The particular importance of a theoretical model for postinjection seismicity is underlined by observations after stimulations of geothermal reservoirs at different locations. For instance, the postinjection phase is relevant for a seismic risk, which up to now has been difficult to control, because processes leading to postinjection events are not well understood. Based on the assumption of pore pressure diffusion as the governing mechanism leading to the triggering of seismic events, we develop a method to calculate the seismicity rate during and after fluid injections. We find that the decay rate of seismicity after termination of injection is very similar to the Omori law, which describes the decay rate of aftershock activity after tectonically driven earthquakes. We propose a modified Omori law for fluid-induced seismicity to estimate the decay rate in dependence on parameters of injection, reservoir rock, and the strength of preexisting fractures in a reservoir. We analyze two models of fracture-strength distribution, which represent stable and unstable preexisting fracture systems. We find that the decay rate of induced seismicity depends on the fracture strength. We present a possible application of this dependency to reservoir characterization. Furthermore, we find that the existence of unstable fractures results in a critical temporal trend of seismicity, which can enhance the occurrence probability of events with large magnitudes shortly after injection has been terminated. We verify our model by finite-element modeling and application to real data collected in case studies performed at Fenton Hill in the United States and Soultz-sous-Forêts in France.

The geological structure of Greece (frequent occurrence of rock formations, existence of faults and fracturing of rocks), the steep topography and mountainous terrain as well as its high seismicity, creates a significant rockfall hazard. During the last decades, rockfalls in Greece are becoming a frequent phenomenon due to the increase of intense rainfall events but also due to the extension of human activities in mountainous areas. The paper presents rockfall hazard in Greece trough an inventory of rockfalls and investigates the correlation of specific factors, namely: a) triggering mechanism (rainfall, seismicity), b) slope angle, c) lithology, d) fault presence, e) block size in the probability of occurrence of these, based on a statistical approach. The time and space frequency of the events is also investigated. Finally, the impact of the events on human and infrastructures (transportation infrastructure, inhabited areas, archaeological sites) is discussed.

La fermeture des mines et la gestion post-minière constituent aujourd’hui un défi majeur car les problèmes engendrés peuvent impacter grandement la sécurité publique. Lorsque les mines sont abandonnées, les systèmes de pompage des eaux souterraines sont généralement arrêtés et l’eau qui remplit progressivement les vides peut affecter la stabilité mécanique des structures souterraines. En général, les mécanismes de la sismicité observée dans les districts post-miniers inondés sont mal compris. Cette thèse porte sur l’étude de la sismicité enregistrée à la suite de l’ennoyage de l’ancien bassin houiller de Gardanne, en Provence, fermée en 2003, qui connaît des problèmes importants de sismicité post-minière. La distribution spatio-temporelle des événements sismiques suggère un lien avec les épisodes de précipitations intenses ainsi qu’avec le pompage actif. La connaissance de l’origine et des mécanismes de déclenchement de l’activité sismique est la clé pour l’évaluation des risques sismiques de l’ensemble du bassin de Gardanne. Les travaux de thèse ont porté sur des questions liées à l’identification précise de l’origine de la source sismique en évaluant deux hypothèses, à la détermination du mécanisme derrière la sismicité, et le lien entre la sismicité et le système hydrogéologique, et en améliorant la détection et la localisation de la microsismicité avec un réseau clairsemé. La nouvelle méthodologie de détection et de localisation développée adapte la méthode BTBB (Poiata) basée sur la forme d’onde complète en surmontant les défis du réseau de surveillance sismique clairsemé, et inclut une nouvelle approche d’élimination du bruit de l’ensemble des données continues ainsi qu’un système de classification basé sur la qualité de la localisation. Un comportement sismique sous forme de clusters a été mis en évidence par le nouveau catalogue sismique 2014-2017, qui a ensuite fait l’objet d’une analyse plus approfondie. L’ensemble des résultats sont en faveur de l’origine des sources sismiques sur la faille en dessous de la mine. Les caractéristiques spatio-temporelles des événements sismiques et les occurrences de multiplets/répéteurs ont fourni une image plus claire des structures géologiques actives et ont permis une interprétation préliminaire des mécanismes de déclenchement possible, basée sur la comparaison avec les données hydrologiques. Malgré la compréhension générale du mécanisme de la sismicité, la magnitude maximale des événements qui peuvent être déclenchés est actuellement difficile à quantifier et à prévoir en raison des limites des données disponibles. En tant que perspective et dans le but de mieux comprendre le risque sismique, des observations plus précises de la sismicité, des paramètres mécaniques et des changements de niveau d’eau dans la zone sismique active sont nécessaires pour améliorer la compréhension de ces facteurs et de leur interconnexion
The closure of mines and post-mining management nowadays present a major challenge as the problems that arise can greatly concern public security. When mines are abandoned, groundwater pumping systems are usually stopped and the water which progressively fills the remaining voids can affect the mechanical stability of underground structures. In general, mechanisms of observed seismicity in flooded, post-mining districts have been poorly understood. As a case study, this thesis focused on the abandoned, flooded coal mine in Gardanne, France, which has been experiencing significant post-mining seismicity problems. Seismic activity in Gardanne mine seems to originate from an interaction between rocks and fluids, as spatio-temporal distribution of events suggests the link with intense rainfall events as well as the active pumping. The knowledge on the origin and the triggering mechanisms of the seismic activity in Gréasque and Regagnas sector is the key for seismic hazard assessment of the entire Gardanne basin. Thesis work focused on questions concerning precise identification of seismic source origin evaluating two hypothesis, determination of the mechanism behind the seismicity, link between seismicity and the hydrogeological system, as well as improving of the detection and location of microseismicity with a sparse network. The new developed detection and location methodology adapts the full waveform-based method BTBB by Poiata by overcoming the challenges of the sparse seismic monitoring network, and includes a novel approach for noise removal from continuous dataset as well as location quality-based classification system. The seismicity clustering behaviour was indicated by the new seismic catalogue 2014-2017, which was further analysed more thoroughly. All results are in favour of the origin of the seismic sources on the fault below the mine. Spatial and temporal characteristics of observed seismic events and multiplet and repeater occurrences provided a clearer image of the active geological structures and allowed a preliminary interpretation of possible mechanisms affecting the initiation and driving of the repeating or after-shock like behavior of seismic events, based on comparison with available hydrological data. Despite the general understanding of the mechanism behind the seismicity, the maximum magnitude of the events that can be triggered is at this moment is difficult to quantify and predict due to limitations of available data. As a prospective, in order to better understand the seismic hazard, more accurate observations of the seismicity, mechanical parameters and water level changes in the seismically active zone are required to improve the understanding and the interconnection between these factors

ABSTRACT: This paper investigates a seismicity sequence that occurred near Stanton, TX between December 2020 and February 2021 with event magnitudes peaking at 4.2. The historically aseismic area has been undergoing shallow salt water disposal (SWD) since the early 1980s, and deep SWD in the last decade. We perform a 3D fully coupled hydro-geomechanical investigation into potential links between the M4.2 event sequence and the surrounding decades-long, multi-zone SWD activities involving 183 SWD wells in a 900 mile2 area. We include faults interpreted from reflection seismic data into the model and survey six fault scenarios with various fault-zone structures and fault upper extents. We compare the modeled Coulomb stress changes against earthquake triggering thresholds obtained from a detailed in-situ stress model, and identify implausible and plausible scenarios. The plausible scenarios yield an excellent match between the critical Coulomb failure function (CFF) propagation and the onset of seismicity in both space and time, and are further supported by their revealing of possible earlier events that were later detected through template matching. Together, these findings strongly suggest a SWD origin of the M4.2 seismicity sequence. The modeling also suggests that near-hypocenter Coulomb stresses are sourced primarily from several deep disposal wells and secondarily from the remaining deep wells and shallower wells given the likely fault configurations. We also analyze roles of fault-zone structures, non-seismogenic faults, and mechanically time-dependent formations. Our work illustrates the importance of physics-based modeling that accounts for faults, formations, wells, and poroelasticity in understanding causes of seismicity. 1. INTRODUCTION Fluid injection, including salt water disposal (SWD) into the subsurface, has long been recognized as capable of inducing earthquakes (Wesso & Nicholson, 1987; Ellsworth, 2013; National Research Council, 2013). There has been an increase in seismicity associated with SWD activities within the United States in the last decade (e.g., Frohlich et al., 2011; Kim 2013; Walsh & Zoback, 2015), and most recently in the Permian basin (e.g., Skoumal & Trugman, 2021). An earlier study proposed empirical criteria for determining whether earthquakes are induced based on their spatial-temporal correlations with injection activities and deviation from regional background seismicity (Davis & Frohlich, 1993). This correlative approach has remained popular in studying origins of induced seismicity, and has been complemented with additional steps, such as earthquake relocation and focal mechanism determination (Kim 2013), analysis of seismicity lineations relative to locally mapped faults (Frohlich et al., 2016), examination of data such as Vp-to-Vs ratio time series (Improta et al., 2015), and space-time clustering analysis (Savvaidis et al., 2020). Some studies employ pore pressure diffusion modeling to further support correlative analysis (e.g., Keranen et al., 2013; Peterie et al., 2018; Chen et al., 2018).

ABSTRACT Large-scale geothermal energy production and carbon geological storage are emerging technologies. Injection of non-native fluids in the subsurface alters reservoir pore pressure and temperature changing the initial state of stress, even beyond the plume and thermal front, which could potentially lead to the reactivation of distant faults. Published work so far usually neglects elastoplastic rock matrix response and effects of plastified reservoir volume on distant stress changes. This paper presents three-dimensional thermo-hydro-mechanical (THM) numerical simulations of (1) a hydrothermal system with injector-producer doublet and (2) a carbon storage site with single injector, both solved with 3D finite element code ParaGeo. First, simulations show that assuming an elastic response for a geothermal reservoir results in more distant stress changes -which can be enough to disturb critically stressed distant faults-, than incorporating a more realistic elastoplastic model for the reservoir rock. Second, injection (without production) of a cold fluid may result in quick distant fault reactivation because the pressure front travels much faster than the temperature front, in the range of a decade or two in our model. Reservoir plasticity plays a negligible role when reservoir pressure increases and effective stress decreases. This work highlights the importance of using a realistic constitutive model and accurate estimation of in-situ stress for evaluating risks on sites subject to heat depletion or fluid injection. INTRODUCTION Subsurface activities that alter the pore pressure and temperature are known to potentially result in non-negligible seismicity (Wesson and Nicholson, 1987; Evans et al., 2012; Guglielmi et al., 2015) and may compromise fault sealing capacity if fault offsets become large (Zoback and Gorelick, 2012). Fluid injection increases pore pressure and may reactivate preexisting faults and fractures, triggering microseismic events (Majer et al., 2007). Reservoir cooling changes effective stress and may alter the state of stress well beyond the thermal plume (Kivi et al., 2022). Recent studies suggest that thermo-hydro-mechanical (THM) processes are likely to operate simultaneously but under different spatial extents, intensifying local stress changes and increasing complexity of distant stress changes (Martínez-Garzón et al., 2014). For example, observed seismicity and history matching at the Geysers geothermal field indicates that preexisting fracture reactivation is the result of reservoir cooling and fracture pressure increase with thermal effects dominating seismicity within the thermal plume (Rutqvist et al., 2015).

Abstract Recently, the elevated levels of seismicity activities in Western Canada have been demonstrated to be linked to hydraulic fracturing operations that developed unconventional resources. The underlying triggering mechanisms of hydraulic fracturing-induced seismicity are still uncertain. The interactions of well stimulation and geology-geomechanical-hydrological features need to be investigated comprehensively. The linear poroelasticity theory was utilized to guide coupled poroelastic modeling and to quantify the physical process during hydraulic fracturing. The integrated analysis is first conducted to characterize the mechanical features and fluid flow behavior. The finite-element simulation is then conducted by coupling Darcy's law and solid mechanics to quantify the perturbation of pore pressure and poroelastic stress in the seismogenic fault zone. Finally, the Mohr-coulomb failure criterion is utilized to determine the spatial-temporal faults activation and reveal the trigger mechanisms of induced earthquakes. The mitigation strategy was proposed accordingly to reduce the potential seismic hazards near this region. A case study of ML 4.18 earthquake in the East Shale Basin was utilized to demonstrate the applicability of the coupled modeling and numerical simulation. Results showed that one inferred fault cut through the Duvernay formation with the strike of NE20°. The fracture half-length of two wells owns an average value of 124 m. The brittleness index deriving from the velocity logging data was estimated to be a relatively higher value in the Duvernay formation, indicating a geomechanical bias of stimulated formation for the fault activation. The coupled poroelastic simulation was conducted, showing that the hydrologic connection between seismogenic faults and stimulated well was established by the end of the 38th stage completion for the east horizontal well. The simulated coulomb failure stress surrounding the fault reached a maximum of 4.15 MPa, exceeding the critical value to cause the fault slip. Hence the poroelastic effects on the inferred fault were responsible for the fault activation and triggered the subsequent ML 4.18 earthquake. It is essential to optimize the stimulation site selection near the existing faults to reduce risks of future seismic hazards near the East Shale Basin.

ABSTRACT Injection-induced seismicity poses a significant technical and socio-political risk to subsurface storage and resource engineering systems. A key challenge is to understand the nucleation process bridged between the dynamic rupture and flow-driven poromechanical deformation (quasi-static) and ensure the ability to capture the onset of ruptures. To address this challenge, a hybrid time-step controller was developed in this research. The controller integrates local discretization error and Coulomb friction and is capable of capturing pre-seismic triggering, co-seismic spontaneous rupture, and arrest. Importantly, the controller operates solely on the solution state, eliminating the need for theoretical indicators that may fail to capture transitions under heterogeneous pressure distribution. The controller was implemented using an A Posteriori approach within a mixed discretization scheme that combines the extended finite element method (XFEM) for poromechanics and the embedded discrete fracture model (EDFM) for multiphase flow, incorporating implicit Newmark scheme for inertial mechanics and a Lagrange Multiplier approach with a slip-weakening friction model to enforce fracture contact constraints. The results demonstrate that the distribution of the pore pressure profiles along the fault may have an effect on the nucleation size. Overall, this study provides insight into the nucleation process and offers a powerful tool for managing the risk of injection-induced seismicity in subsurface storage and resource engineering systems. INTRODUCTION Induced seismicity is a phenomenon that has become increasingly relevant as human activities such as fracking and wastewater disposal have been linked to earthquakes. One knowledge gap in the understanding of this process pertains to the critical size of a ruptured sliding patch along a fault patch beyond which, spontaneous sliding is to occur (producing considerable seismic events). An understanding of the nucleation process is essential to predicting and managing injection processes. Early laboratory studies of stick-slip shear failures suggest that the nucleation process involves two phases. The first stage entails a slow and longer-term propagation of slip. This may be followed by a sudden transition to the second phase with shorter periods of accelerated slip, where the sliding patch size and velocity accelerate very rapidly. The physical properties of the fault, such as its frictional behavior, and the normal stress acting on it are known to strongly influence this nucleation process (Dieterich, 1978; Okubo and Dieterich, 1984; Ohnaka and Shen, 1999). Reported theoretical and numerical efforts aim to quantitatively understand the nucleation process under idealized conditions. A particular focus has been on deriving an instability criterion for either slip-weakening or rate-and-state friction models (e.g., Campillo and Ionescu (1997); Favreau et al. (1999); Uenishi and Rice (2003); Rubin and Ampuero (2005); Ampuero and Rubin (2008); Kaneko and Ampuero (2011); Latour et al. (2013); Gvirtzman and Fineberg (2021)). According to the driving mechanisms behind the growth of the patch, the derivation of this instability criterion can be divided into two major classes: one is based on linear stability analysis where a stress criterion is applied because the yielding of the contact surface pre-dominates, and another is based on Griffth's criterion with energy consideration when the fracture mechanics takes over. However, the theoretical nucleation size assumes uniform stress distributions and only considers mechanics. Under realistic injection conditions, the fluid pressure field is spatially and temporally variable. This work explores the influence of such complexity on the nucleation process.

Abstract The existence of faults, pre-existing hydraulic fractures, and depleted areas can have negative impacts on the development of unconventional reservoirs using multi-fractured horizontal wells (MFHWs). For example, the triggering of fault slippage through hydraulic fracturing can create the environmental hazard known as induced seismicity (earthquakes caused by hydraulic fracturing). A premium has therefore been placed on the development of technologies that can be used to identify the locations of fault systems (particularly if they are subseismic), as well as pre-existing hydraulic fractures and depleted areas that can similarly negatively impact reservoir exploitation. The objective of this study is to develop a diagnostic tool to identify these conditions using DFIT-FBA. DFIT-FBA is a modified diagnostic fracture injection test (DFIT) whereby a sequence of injection and flowback steps are performed to estimate minimum in-situ stress, fracture surface area, reservoir pressure, and permeability in shale and tight reservoirs. The time- and cost-efficiency of the DFIT-FBA method provides an opportunity to conduct multiple field tests at a single point, or along the lateral section of a horizontal well, without significantly delaying the completion program. The proposed diagnostic tool uses an analytical model which considers critical processes and mechanisms occurring during a DFIT-FBA test, including wellbore storage, leakoff rate, and fracture stiffness development. The results of analytical modeling demonstrate that faults, pre-existing hydraulic fractures, and depleted areas of the reservoir can be identified either by implementing multiple cycles of the DFIT-FBA test at a single point, or by applying multiple DFIT-FBA tests at different points along the lateral section of a horizontal well or at different wells. The analytical model is first verified using a fully-coupled hydraulic fracture, reservoir, and wellbore simulator, and flowing pressure responses in the presence of different reservoir heterogeneities are then illustrated. Practical application of the proposed method is demonstrated using DFIT-FBA field examples performed in a tight reservoir. Analysis of the field examples results in the conclusion that a fault occurs near the toe of the horizontal lateral. This finding was confirmed by other field information and provides the opportunity to modify the main-stage hydraulic fracturing design to avoid induced seismicity events. This study proposes a novel, fast, and low-cost approach for identifying faults, pre-existing hydraulic fractures, and depleted areas using the DFIT-FBA test. The recommended approach can help engineers to characterize the reservoir quality along a horizontal well, as well as identify features/conditions that could negatively influence reservoir development, such as faults (and the possibility of creating induced seismicity), pre-existing hydraulic fractures, and reservoir depletion.

Studying earthquakes in Baffin Bay and the surrounding regions is challenging. There is no knowledge of earthquake activity in this region prior to 1933 when a moment magnitude (MW) 7.4 earthquake occurred in Baffin Bay. With improved instrumentation, increased seismograph coverage in the north, and modern analysis techniques, knowledge and understanding of earthquakes in the Baffin region is improving. Active seismic zones include Baffin Bay, the east coast of Baffin Island, and the Labrador Sea, separated by areas of low seismicity. Focal-mechanism solutions show a mix of faulting styles, predominantly strike-slip and thrust. Regional stress-axes orientations show more consistency, which suggests that activity is occurring on previously existing structures in response to the current stress field. There is little correlation between earthquake epicentres in Baffin Bay and mapped structures. Glacial isostatic adjustment may be a triggering mechanism for earthquakes in the Baffin region, but modelling efforts have yielded equivocal results.