Letteratura scientifica selezionata sul tema "Origin of seismicity"
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Articoli di riviste sul tema "Origin of seismicity":
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Lukk, A. A., V. G. Leonova e A. Ya Sidorin. "Revisiting the Origin of Seismicity in Fennoscandia". Izvestiya, Atmospheric and Oceanic Physics 55, n. 7 (dicembre 2019): 743–58. http://dx.doi.org/10.1134/s000143381907003x.
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Vasudevan, K., D. W. Eaton e J. Davidsen. "Intraplate seismicity in Canada: a graph theoretic approach to data analysis and interpretation". Nonlinear Processes in Geophysics 17, n. 5 (4 ottobre 2010): 513–27. http://dx.doi.org/10.5194/npg-17-513-2010.
Abstract (sommario):
Abstract. Intraplate seismicity occurs in central and northern Canada, but the underlying origin and dynamics remain poorly understood. Here, we apply a graph theoretic approach to characterize the statistical structure of spatiotemporal clustering exhibited by intraplate seismicity, a direct consequence of the underlying nonlinear dynamics. Using a recently proposed definition of "recurrences" based on record breaking processes (Davidsen et al., 2006, 2008), we have constructed directed graphs using catalogue data for three selected regions (Region 1: 45°−48° N/74°−80° W; Region 2: 51°−55° N/77°−83° W; and Region 3: 56°−70° N/65°−95° W), with attributes drawn from the location, origin time and the magnitude of the events. Based on comparisons with a null model derived from Poisson distribution or Monte Carlo shuffling of the catalogue data, our results provide strong evidence in support of spatiotemporal correlations of seismicity in all three regions considered. Similar evidence for spatiotemporal clustering has been documented using seismicity catalogues for southern California, suggesting possible similarities in underlying earthquake dynamics of both regions despite huge differences in the variability of seismic activity.
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Goltz, C. "Decomposing spatio-temporal seismicity patterns". Natural Hazards and Earth System Sciences 1, n. 1/2 (30 giugno 2001): 83–92. http://dx.doi.org/10.5194/nhess-1-83-2001.
Abstract (sommario):
Abstract. Seismicity is a distributed process of great spatial and temporal variability and complexity. Efforts to characterise and describe the evolution of seismicity patterns have a long history. Today, the detection of changes in the spatial distribution of seismicity is still regarded as one of the most important approaches in monitoring and understanding seismicity. The problem of how to best describe these spatio-temporal changes remains, also in view of the detection of possible precursors for large earthquakes. In particular, it is difficult to separate the superimposed effects of different origin and to unveil the subtle (precursory) effects in the presence of stronger but irrelevant constituents. I present an approach to the latter two problems which relies on the Principal Components Analysis (PCA), a method based on eigen-structure analysis, by taking a time series approach and separating the seismicity rate patterns into a background component and components of change. I show a sample application to the Southern California area and discuss the promising results in view of their implications, potential applications and with respect to their possible precursory qualities.
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Goertz-Allmann, Bettina P., e Stefan Wiemer. "Geomechanical modeling of induced seismicity source parameters and implications for seismic hazard assessment". GEOPHYSICS 78, n. 1 (1 gennaio 2013): KS25—KS39. http://dx.doi.org/10.1190/geo2012-0102.1.
Abstract (sommario):
We simulate induced seismicity within a geothermal reservoir using pressure-driven stress changes and seismicity triggering based on Coulomb friction. The result is a forward-modeled seismicity cloud with origin time, stress drop, and magnitude assigned to each individual event. Our model includes a realistic representation of repeating event clusters, and is able to explain in principle the observation of reduced stress drop and increased [Formula: see text]-values near the injection point where pore-pressure perturbations are highest. The higher the pore-pressure perturbation, the less critical stress states still trigger an event, and hence the lower the differential stress is before triggering an event. Less-critical stress states result in lower stress drops and higher [Formula: see text]-values, if both are linked to differential stress. We are therefore able to establish a link between the seismological observables and the geomechanical properties of the source region and thus a reservoir. Understanding the geomechanical properties is essential for estimating the probability of exceeding a certain magnitude value in the induced seismicity and hence the associated seismic hazard of the operation. By calibrating our model to the observed seismicity data, we can estimate the probability of exceeding a certain magnitude event in space and time and study the effect of injection depth and crustal strength on the induced seismicity.
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Khutorskoy, Mikhail, Emil Botev, Valentina Protopopova, Aleksey Benderev e Elena Tevelova. "Heat Flow and Seismicity in Bulgaria". Engineering Geology and Hydrogeology 34, n. 1 (2020): 53–65. http://dx.doi.org/10.52321/igh.34.1.53.
Abstract (sommario):
The study of intra-earth processes requires a comprehensive approach, which should be based on the understanding different nature and origin depth of terrestrial processes. In this regard, the problem of the relationship between seismicity and heat flow in the lithosphere is of interest. We analyzed seismic observation data in Bulgaria from 1981 to 2018 using statistical methods. A significant correlation was found between the heat flow and the earthquakes magnitude, as well as between the thickness of thermal lithosphere and the magnitude. To assess the released friction heat and hydrodynamic processes during the earth’s crust movements, it is necessary to develop theoretical models based on a comprehensive analysis of the geological structure and geophysical fields in seismically active regions.
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Candela, Thibault, Maarten Pluymaekers, Jean-Paul Ampuero, Jan-Diederik van Wees, Loes Buijze, Brecht Wassing, Sander Osinga, Niels Grobbe e Annemarie G. Muntendam-Bos. "Controls on the spatio-temporal patterns of induced seismicity in Groningen constrained by physics-based modelling with Ensemble-Smoother data assimilation". Geophysical Journal International 229, n. 2 (11 dicembre 2021): 1282–308. http://dx.doi.org/10.1093/gji/ggab497.
Abstract (sommario):
SUMMARY The induced seismicity in the Groningen gas field, The Netherlands, presents contrasted spatio-temporal patterns between the central area and the south west area. Understanding the origin of this contrast requires a thorough assessment of two factors: (1) the stress development on the Groningen faults and (2) the frictional response of the faults to induced stresses. Both factors have large uncertainties that must be honoured and then reduced with the observational constraints. Ensembles of induced stress realizations are built by varying the Poisson's ratio in a poro-elastic model incorporating the 3-D complexities of the geometries of the Groningen gas reservoir and its faults, and the historical pore pressure distribution. The a priori uncertainties in the frictional response are mapped by varying the parameters of a seismicity model based on rate-and-state friction. The uncertainties of each component of this complex physics-based model are honoured through an efficient data assimilation algorithm. By assimilating the seismicity data with an Ensemble-Smoother, the prior uncertainties of each model parameter are effectively reduced, and the posterior seismicity rate predictions are consistent with the observations. Our integrated workflow allows us to disentangle the contributions of the main two factors controlling the induced seismicity at Groningen, induced stress development and fault frictional response. Posterior distributions of the model parameters of each modelling component are contrasted between the central and south west area at Groningen. We find that, even after honouring the spatial heterogeneity in stress development across the Groningen gas field, the spatial variability of the observed induced seismicity rate still requires spatial heterogeneity in the fault frictional response. This work is enabled by the unprecedented deployment of an Ensemble-Smoother combined with physics-based modelling over a complex case of reservoir induced seismicity.
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Paudyal, Harihar. "Fluctuation of seismic activity associated with 1999 Chamoli earthquake". Himalayan Physics 2 (31 luglio 2011): 11–15. http://dx.doi.org/10.3126/hj.v2i2.5203.
Abstract (sommario):
The Chamoli earthquake of March 28, 1999 (Mb 6.6, Origin time: 19:05:12, epicenter at 30.5° N 79.4° E and Focal depth 23 km) occurred in the Himalayan front arc which caused severe damage in the region. Anomalous seismic activity associated with this recent devastating earthquake in the Central Himalaya region in an area bounded by 30.0°-31.0° N and 79.0°-80.0° E have been studied using seismicity data from 1980-2000. The preparatory zone is delineated using the temporal and the spatial distribution of earthquakes, considering the events with cutoff magnitude mb ≥ 4.3. Daily number of events as well as cumulative number of earthquake with time within the preparatory zone has been considered as basis for identification of anomalous seismicity. Accordingly four anomalous episodes: Normal/ background (N); Anomalous/ swarm (A); Precursory gap (G) and Mainshock sequence (M) are identified. It is observed that the event was preceded by well defined patterns of anomalous seismicity/ precursory swarm which was lasted for about seven month and had started about three years and four months prior to mainshock.Key words: Anomalous seismicity; Central Himalaya; Precursory swarm; Earthquake forecastThe Himalayan Physics Vol.2, No.2, May, 2011Page: 11-15Uploaded Date: 31 July, 2011
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Valenzuela-Malebrán, Carla, Simone Cesca, Sergio Ruiz, Luigi Passarelli, Felipe Leyton, Sebastian Hainzl, Bertrand Potin e Torsten Dahm. "Seismicity clusters in Central Chile: investigating the role of repeating earthquakes and swarms in a subduction region". Geophysical Journal International 224, n. 3 (21 novembre 2020): 2028–43. http://dx.doi.org/10.1093/gji/ggaa562.
Abstract (sommario):
SUMMARY Seismicity along subduction interfaces is usually dominated by large main-shock–aftershock sequences indicative of a continuum distribution of highly coupled large asperities. In the past decades, however, the increased resolution of seismic catalogues at some subduction zone seems to indicate instead a more complex rheological segmentation of the interface. Large and megathrust earthquake ruptures seem interspersed among regions of low seismic coupling and less stress buildup. In this weaker zone, the strain is primarily released via a combination of moderate-size swarm-like seismicity and aseismic slip. Along the Chilean subduction zone, the densification of the seismic network allowed for the identification of localized seismic clusters, some of them appearing in the form of swarms before megathrust earthquakes. The origin and driving processes of this seismic activity have not yet been identified. In this study, we follow a systematic approach to characterize the seismicity at two persistent clusters in Central Chile, one located offshore Navidad and one inland, at ∼40 km depth beneath Vichuquén, which occurred throughout ∼20 yr. We investigated these clusters, by deriving high-resolution hypocentral locations and moment tensors and performing a detailed analysis of spatio-temporal patterns, magnitude and interevent time distributions of the clustered earthquakes. Both clusters are characterized by weak to moderate seismicity (below Mw 6) and stand out as clear seismicity rate and Benioff strain anomalies. At the Navidad cluster, seismicity occurs in the form of swarms, with a characteristic duration of 2–7 d and location and thrust mechanisms compatible with activity on the slab interface. Conversely, we find at Vichuquén activity dominated by thrust earthquakes occurring as repeaters on the slab interface, with a slip rate of approximately ∼5.0 cm yr−1. We attribute these clusters to local features of the subducting plate: the Navidad swarms are likely driven by repeated high pore pressure transients along a pre-fractured patch of the slab, while the seismicity at the Vichuquén cluster is interpreted as the result of a subducting seamount. Both clusters have been active before and after the Mw 8.8 Maule earthquake and persisted afterwards with the seismicity decay following the Omori law. These interactions are especially evident for the Vichuquén cluster, where the seismicity rate increased considerably after the Maule earthquake and continues to be an area of clearly elevated seismicity rate compared to its surroundings.
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Shestopalov, I. P., e E. P. Kharin. "Relationship between solar activity and global seismicity and neutrons of terrestrial origin". Russian Journal of Earth Sciences 14, n. 1 (12 marzo 2014): 1–10. http://dx.doi.org/10.2205/2014es000536.
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De Barros, Louis, Ivan Lokmer e Christopher J. Bean. "Origin of spurious single forces in the source mechanism of volcanic seismicity". Journal of Volcanology and Geothermal Research 262 (luglio 2013): 1–6. http://dx.doi.org/10.1016/j.jvolgeores.2013.06.006.
Tesi sul tema "Origin of seismicity":
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Namjesnik, Dalija. "Origin of seismicity related to a flooded abandoned coal mining district at Gardanne, Provence, France". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0116.
Abstract (sommario):
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 interconnexionThe 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
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Arnott, Frank Walter. "Seismicity in the Welkom Area, O.F.S. (with special reference to the origin of the 1976-12-8 event)". Thesis, 2014. http://hdl.handle.net/10539/15737.
Capitoli di libri sul tema "Origin of seismicity":
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Gerya, Taras V. "Origin, Evolution, Seismicity, and Models of Oceanic and Continental Transform Boundaries". In Plate Boundaries and Natural Hazards, 39–76. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119054146.ch3.
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Doglioni, Carlo. "Origin of Seismicity in Italy as a Clue for Seismic Hazard". In Lecture Notes in Civil Engineering, 153–65. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-21187-4_10.
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Lowrie, William. "4. Seismicity—the restless Earth". In Geophysics: A Very Short Introduction, 47–68. Oxford University Press, 2018. http://dx.doi.org/10.1093/actrade/9780198792956.003.0004.
Abstract (sommario):
Hundreds of thousands of earthquakes occur worldwide each year, but most of them go unnoticed. Only a few are very destructive. Most earthquakes have a tectonic origin and happen in well-defined, relatively narrow seismic zones. ‘Seismicity—the restless Earth’ first describes the elastic rebound model that explains how an earthquake occurs. There are two measures of the size of an earthquake: its magnitude and intensity. Magnitude is a measure of the energy released by the earthquake classified by the Richter scale, while intensity is a qualitative measure based on observed effects using a twelve-part scale. Maps of the locations of earthquake epicentres show that these are concentrated in narrow seismically active zones. Earthquake monitoring and prediction are discussed.
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Rajan, S. Ravi. "Environment and Development in India". In China–India. British Academy, 2014. http://dx.doi.org/10.5871/bacad/9780197265673.003.0011.
Abstract (sommario):
The purpose of this chapter is to explore some of the key debates about India’s environment and development. It begins by summarising some of the country’s key sustainability indicators. It then examines the natural resource management sector, focusing on forestry and irrigation. Finally, it explores the threats posed by environmental risks of technological origin – by considering five high profile cases – the Bhopal Gas Disaster of 1984; the controversy over Genetically Modified Organisms (GMOs); the seismicity concerns of the TEHRI dam; the handling of pollution and transportation policy in New Delhi; and the debate on nuclear safety.
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Gatinsky, Yuriy, e Tatiana Prokhorova. "Tentative Intracontinental Seismic Activity in South Siberia and Russian Far East". In Earthquakes - From Tectonics to Buildings. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95073.
Abstract (sommario):
Overwhelming majority of minor, strong and major earthquakes in south Siberia and Russian Far East coincide with relatively narrow intracontinental zones on the boundaries of blocks and lithosphere plates. The geodynamic activity of these zones connects, besides the plate interaction, with deep lithosphere structure and anomalies of the different geophysical fields as well as with blocks’ kinematics. Authors’ located areas of the seismic centers origin and the possible manifestations of the high seismicity based on the distribution of the maximal volumes of releasing seismic energy. We established these areas, with certain care, in the northeast Altai and adjacent part of the west Sayany, in the west of the east Sayany, around the Baikal Lake and in northwest Transbaikalia, in the east of Transbaikalia between the Vitim River and upper stream of the Aldan River, and in the north of the Sakhalin Island. The majority of minor and strong, rarely major, earthquakes took place in these areas. Deep and near surface structural peculiarities influence on these areas’ geodynamics and allow establishing possible levels of seismic energy releasing. We draw areas of intensive seismic energy releasing with its calculating for each from investigated regions. They gravitate towards interblock zones, which separate crust blocks and the North Eurasian Lithosphere Plate. The fulfilled investigation allows establishing specific areas of the increased seismicity in south Siberia, Russian Far East and adjacent territories.
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Beck, Christian. "Lake sediments as late Quaternary paleoseismic archives: Examples in the northwestern Alps and clues for earthquake-origin assessment of sedimentary disturbances". In Geological Criteria for Evaluating Seismicity Revisited: Forty Years of Paleoseismic Investigations and the Natural Record of Past Earthquakes. Geological Society of America, 2011. http://dx.doi.org/10.1130/2011.2479(07).
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Rovey, Charles W., Damon J. Bassett e Matthew P. McKay. "Ordovician and Mississippian stratigraphy in southwestern Missouri, USA". In Field Excursions from the 2021 GSA Section Meetings, 181–200. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.0061(08).
Abstract (sommario):
ABSTRACT A succession of Ordovician and Mississippian carbonates, separated unconformably, is exposed across the southern flank of the Ozark Dome in southwest Missouri. Deposits of both periods exemplify typical facies of the Midwestern United States: carbonate tidal-flat assemblages for the Early Ordovician and carbonate shelf environments for the Early–Middle Mississippian. The basic stratigraphic sequence of these deposits has been known for over a century, but interesting features remain to be addressed. Thin discontinuous sandstones are present within the Early Ordovician Cotter Dolomite, but the informal Swan Creek sandstone member seems anomalous. This sandstone can exceed 5 m in thickness and is fairly continuous across southwest Missouri. Most Ordovician sandstones in Missouri mark major transgressions above regional unconformities, but not the Swan Creek, and there is no obvious source of the sand. Therefore, we hypothesize that the Swan Creek represents reworked eolian dunes blown across the broad peritidal environment. Clastic sandstone dikes, apparently sourced from the Swan Creek, cut across beds of Cotter Dolomite near faults. We propose that these dikes are evidence of local faulting and seismicity during the Early Ordovician. Early and Middle Mississippian limestones comprise a sequence of shelf deposits, although mud mounds and other facies changes near the Missouri-Arkansas line mark the edge of the Mississippian shelf and the transition to a ramp setting. Early Mississippian carbonate deposition was interrupted by a short and localized influx of siliciclastic sediment comprising the Northview Formation. The Northview has additional characteristics consistent with a river-dominated deltaic deposit, which we suggest as its origin. If correct, this hypothesis implies that the history of tectonic features in the Midwest is more complicated than yet known. Finally, facies changes within and between the local Mississippian formations may record an early crustal response to the impending Ouachita orogeny farther to the south.
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Marple, Ronald T., Robert J. Altamura, Shelton S. Alexander e James D. Hurd. "Evidence for post-Triassic brittle faults in eastern Connecticut and south-central Massachusetts using LiDAR, geomorphic, and geophysical data combined with field observations: Implications for the origin of the Moodus area seismicity". In Geological Society of America Special Papers, 51–88. Geological Society of America, 2013. http://dx.doi.org/10.1130/2012.2493(04).
Atti di convegni sul tema "Origin of seismicity":
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Fortier, Eric. "Different Origin of Microseismic Activity Highlighted by Magnitude of Completeness and B-value Computation Case Study on Underground Salt Exloitation and Storage". In ADIPEC. SPE, 2023. http://dx.doi.org/10.2118/216752-ms.
Abstract (sommario):
Abstract Seismic monitoring becomes an important and reliable method to identify instabilities induced by underground operations. Depending on the type of operations, as underground storage in salt caverns, hydraulic stimulation, or reservoir monitoring, different types of seismic activities are identified. After the location of micro-seismic events, different parameters are computed, like the peak ground velocities, the magnitudes, the source radius, or the B-value. When a network does not have enough sensors to calculate reliable focal mechanisms, the use of such parameters can help us to better understand the seismic origins, their occurrence, and what induced the micro-earthquakes. The Richter magnitude is an important attribute to characterize the seismic energy induced by cavern activities. The magnitude is computed from the seismic moment (Aki, 1966; Kanamori, 1977). The magnitude of completeness (Mc) is the minimum magnitude above which all earthquakes within a certain perimeter are reliably detected. The B-value computation corresponds to the slope of the number of located events versus their magnitude on a log scale. It gives an indication of the relation between the "earthquake" size and its occurrence. It is generally accepted that b-value around 1 is observed for "structural origin" and around 2 is observed for "small induced micro-seismicity". Some sites are leaching or storing gas in underground caverns inside salt formation. Those sites are equipped of seismic networks using sensors in shallow buried arrays to monitor the associated microseismic activity. A significant seismicity is occurring since many years of monitoring. According to the B-Value computation, we manage to identify three types of seismicity. First one is cavern leaching seismicity associated to a B-value close to 2, indicating small energy activity located in the vicinity of the caverns. The second and third ones are gas storage caverns, and salt coverage seismic origin, with a B-value close to one, showing a more important seismicity in term of energy, induced by micro-structure re-activation or insoluble layers sliding. This seismicity interpretation allows a new viewing of understanding the micro-earthquakes origin induced by underground challenges. Taking into account the geological context, we can better define the nature of the seismicity by computing such parameters. The only factor needed to compute a reliable magnitude of completeness and B-value, is the necessity of a significant database of seismic events.
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Jin, L., R. Lippoldt, W. J. Curry, S. Hussenoeder e P. Bhargava. "A Numerical Investigation of the 2020 M4.2 Stanton, Texas Seismicity Sequence Using 3D Poroelastic Modeling". In 56th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2022. http://dx.doi.org/10.56952/arma-2022-2023.
Abstract (sommario):
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).
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Altamura, Robert. "THE EASTFORD FAULT - A REGIONAL LATE–STAGE FAULT ZONE IN EASTERN CONNECTICUT: IMPLICATIONS FOR THE ORIGIN OF MOODUS AREA SEISMICITY AND AUDIBLE EARTHQUAKES". In Northeastern Section-56th Annual Meeting-2021. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021ne-361866.
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Woźniakowska, P., L. Eisner e M. Musil. "The Largest Event Of The Dfw Seismicity 3 Years After The Injection Termination - Is It An Evidence For Natural Origins Of Dfw Seismicity?" In Seventh EAGE Workshop on Passive Seismic 2018. Netherlands: EAGE Publications BV, 2017. http://dx.doi.org/10.3997/2214-4609.201800061.
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Hui, Gang, Shengnan Chen e Fei Gu. "A Novel Coupled Approach to Investigate the Spatiotemporal Evolution of Fracturing-Induced Seismicity: Case Study". In SPE Hydraulic Fracturing Technology Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/204156-ms.
Abstract (sommario):
Abstract The recent seismicity rate increase in Fox Creek is believed to be linked to the hydraulic fracturing operations near the region. However, the spatiotemporal evolution of hydraulic fracturing-induced seismicity is not well understood. Here, a coupled approach of geology, geomechanics, and hydrology is proposed to characterize the spatiotemporal evolution of hydraulic fracturing-induced seismicity. The seismogenic faults in the vicinity of stimulated wells are derived from the focal mechanisms of mainshock event and lineament features of induced events. In addition, the propagation of hydraulic fractures is simulated by using the PKN model, in combination with inferred fault, to characterize the possible well-fault hydrological communication. The original stress state of inferred fault is determined based on the geomechanics analysis. Based on the poroelasticity theory, the coupled flow-geomechanics simulation is finally conducted to quantitatively understand the fluid diffusion and poroelastic stress perturbation in response to hydraulic fracturing. A case study of a moment-magnitude-3.4 earthquake near Fox Creek is utilized to demonstrate the applicability of the coupled approach. It is shown that hydraulic fractures propagated along NE45° and connected with one North-south trending fault, causing the activation of fault and triggered the large magnitude event during fracturing operations. The barrier property of inferred fault under the strike-slip faulting regime constrains the nucleation position of induced seismicity within the injection layer. The combined changes of pore pressure and poroelastic stress caused the inferred fault to move towards the failure state and triggered the earthquake swarms. The associated spatiotemporal changes of Coulomb Failure Stress along the fault plane is well in line with the spatiotemporal pattern of induced seismicity in the studied case. Risks of seismic hazards could be reduced by decreasing fracturing job size during fracturing stimulations.
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Misini, Labeat, Jelena Ristic, Viktor Hristovski e Danilo Ristic. "TESTING OF MODELS OF ORIGINAL AND UPGRADED CONNECTION BETWEEN RC FLOOR-BEAM AND COLUMN USED IN MODERN PRECAST HALL SYSTEM". In 2nd Croatian Conference on Earthquake Engineering. University of Zagreb Faculty of Civil Engineering, 2023. http://dx.doi.org/10.5592/co/2crocee.2023.72.
Abstract (sommario):
The design and construction of modern, globally upgraded and seismically safe industrial hall systems (SSIH Systems) is currently viewed as an activity of extraordinary importance since these structures most frequently house new advanced and robotically conceptualized industrial machines and equipment, whose value multiply exceeds the value of the integral structures. The SSIH systems are of vital importance because it is only by their practical application that efficient and continuous functioning of important production industrial systems and compounds is provided. The achieved safety margins, the actual seismic performances and the present limitations of the used pin-based floor-beam column connections of the existing precast N-system were integrally confirmed by the original results obtained from the conducted experimental tests of the constructed connection prototype models. The precast N-system is commonly used for intensive construction of large industrial structures in different regions and countries, including areas of Europe and wider characterized by high seismicity. The initial results obtained from the laboratory test of the constructed large-scale prototype model representing a common floor-beam column (CFBC) connection confirmed the actual bearing capacity of the connection, the damage propagation pattern and the specific total failure mode. To investigate possible upgrading of the connection safety, a specific supplementary test was performed using the created and constructed new experimental model, representing an upgraded floor-beam column (UFBC) connection by application of an improved concrete confinement and use of larger diameters of steel connection pins (dowels). The main conclusion regarding the safety increase was that such common upgrading concept of pin-based connections could not be considered as a basic adequate approach since it was able to provide only limited upgrading effects. The existing need for creation of a new, advanced, experimentally proved and effective innovative upgrading method was clearly pointed out.
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Wenning, Q. C., N. Gholizadeh Doonechaly, A. Shakas, M. Hertrich, H. Maurer, D. Giardini, Bedretto Team et al. "Heat Propagation Through Fractures During Hydraulic Stimulation in Crystalline Rock". In 56th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2022. http://dx.doi.org/10.56952/arma-2022-2112.
Abstract (sommario):
ABSTRACT: The Bedretto Underground Laboratory for Geosciences and Geoenergies (BULGG) is located in central Switzerland and serves as a test bed for geothermal energy research. Several boreholes were drilled from the laboratory section (ca. 1.1 km overburden) to serve as injection boreholes for stimulation and geophysical monitoring boreholes. During a hydraulic stimulation injection in winter 2020 into injection borehole ST2 interval ranging from 313 to 320 m, we observe a thermal perturbation using distributed fiber optic temperature sensing in a neighboring open borehole (MB1) at a depth of 275 m to 295 m. Prior to injection, there is a thermal anomaly in MB1 at about 289 m due to natural fracture fluid flow. Below this depth the temperature is approximately 1.5 °C higher than above. During injection there is a gradual upward movement of the thermal anomaly to ca. 278 m depth. After injection is stopped, the thermal signal gradually recovers to the original depth. The cause for such a temperature change is potentially due to increased warm water flow reaching the base of MB1 from deeper ST2 or poro-elastic fracture closure of the cold-water conducting fractures at 278 and 289 m depth in MB1 during stimulation. 1. INTRODUCTION Geothermal energy is considered a sustainable form of power generation. While the earth generates over three times the total yearly human energy consumption (Pollack et al., 1993; Davies and Davies, 2010), the use of geothermal energy for power generation at the industrial scale has been limited, largely in part due to the need to engineer and stimulate reservoirs at significant depth to tap into the heat sources. Such ‘enhanced’ or ‘engineered’ geothermal systems (EGS) require hydraulic stimulation or fracturing to achieve economic heat extraction, adding to economic impact of drilling and completing a well, as well as creating additional difficulties like induced seismicity. To date, there are just a few examples from across the world which have had success in producing heat from EGS reservoirs (Brown, 1995; Albright and Pearson, 1982; Moore et al., 2018; Link et al., 2020; Genter et al., 2010).
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Li, X., F. Zhang, M. Du, N. Xiu, D. Weng, B. Cai, H. Fu e L. Huang. "Numerical Study on Permeability Evolution of a Natural Fracture in Granite During Shearing". In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0196.
Abstract (sommario):
ABSTRACT The permeability evolution of natural fractures during shearing is one of the critical issues in enhanced geothermal system (EGS). In this study, a series of numerical simulations of shear-flow tests under different normal stresses were carried out to investigate the permeability evolution and shear behavior of a natural fracture during shearing. All numerical simulations in this study were implemented based on a coupled hydro-mechanical pore network model (PNM) of fluid flow in discrete element method (DEM). Fluid grids in the simulations are continuously refreshed as the shear progresses. The results indicate that the fracture permeability positively correlates with the shear displacement when the normal stress is relatively large. The essence of permeability evolution is the variation of the local aperture distribution. Greater fracture roughness makes it easier to form high-permeability pathways. Besides, high normal stress amplifies the effect of fracture roughness on permeability evolution. These findings can contribute to a better understanding of the hydraulic-mechanical coupling effects in the fracture shearing process of EGS. INTRODUCTION Enhanced geothermal system (EGS), as a key technology for the extraction and utilization of geothermal energy from high-temperature rock masses in deep formations, has become a research and development hotspot in the field of earth energy and renewable energy (Huang et al., 2018). Many studies have shown that fluid injection in EGS may lead to induced seismicity (Hanano, 2004; Zang et al., 2014; Gaucher et al., 2015; Kim et al., 2018). EGS utilizes fluid to create a new fracture network in hot dry rock or to further expand the original natural fracture network, thereby creating a large number of fluid flow channels. This process involves a series of complex fluid-solid coupling effects and may cause shear slips of fractures or faults (Ishibashi et al., 2018). Fracture shear slip is often accompanied by the evolution of fracture permeability, and the evolution process of fracture permeability can reflect the frictional stability of fractures to a certain extent (Wu et al., 2017). It can be seen that the study of the permeability evolution process and its influence factors in the shearing process of natural fractures is of great significance for evaluating the safety and stability of EGS.
Rapporti di organizzazioni sul tema "Origin of seismicity":
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Visser, R., H. Kao, R. M. H. Dokht, A. B. Mahani e S. Venables. A comprehensive earthquake catalogue for northeastern British Columbia: the northern Montney trend from 2017 to 2020 and the Kiskatinaw Seismic Monitoring and Mitigation Area from 2019 to 2020. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/329078.
Abstract (sommario):
To increase our understanding of induced seismicity, we develop and implement methods to enhance seismic monitoring capabilities in northeastern British Columbia (NE BC). We deploy two different machine learning models to identify earthquake phases using waveform data from regional seismic stations and utilize an earthquake database management system to streamline the construction and maintenance of an up-to-date earthquake catalogue. The completion of this study allows for a comprehensive catalogue in NE BC from 2014 to 2020 by building upon our previous 2014-2016 and 2017-2018 catalogues. The bounds of the area where earthquakes were located were between 55.5°N-60.0°N and 119.8°W-123.5°W. The earthquakes in the catalogue were initially detected by machine learning models, then reviewed by an analyst to confirm correct identification, and finally located using the Non-Linear Location (NonLinLoc) algorithm. Two distinct sub-areas within the bounds consider different periods to supplement what was not covered in previously published reports - the Northern Montney Trend (NMT) is covered from 2017 to 2020 while the Kiskatinaw Seismic Monitoring and Mitigation Area (KSMMA) is covered from 2019 to 2020. The two sub-areas are distinguished by the BC Oil & Gas Commission (BCOGC) due to differences in their geographic location and geology. The catalogue was produced by picking arrival phases on continuous seismic waveforms from 51 stations operated by various organizations in the region. A total of 17,908 events passed our quality control criteria and are included in the final catalogue. Comparably, the routine Canadian National Seismograph Network (CNSN) catalogue reports 207 seismic events - all events in the CNSN catalogue are present in our catalogue. Our catalogue benefits from the use of enhanced station coverage and improved methodology. The total number of events in our catalogue in 2017, 2018, 2019, and 2020 were 62, 47, 9579 and 8220, respectively. The first two years correspond to seismicity in the NMT where poor station coverage makes it difficult to detect small magnitude events. The magnitude of completeness within the KSMMA (ML = ~0.7) is significantly smaller than that obtained for the NMT (ML = ~1.4). The new catalogue is released with separate files for origins, arrivals, and magnitudes which can be joined using the unique ID assigned to each event.