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Verberne, Berend A., Oliver Plümper, and Christopher J. Spiers. "Nanocrystalline Principal Slip Zones and Their Role in Controlling Crustal Fault Rheology." Minerals 9, no. 6 (May 28, 2019): 328. http://dx.doi.org/10.3390/min9060328.
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Principal slip zones (PSZs) are narrow (<10 cm) bands of localized shear deformation that occur in the cores of upper-crustal fault zones where they accommodate the bulk of fault displacement. Natural and experimentally-formed PSZs consistently show the presence of nanocrystallites in the <100 nm size range. Despite the presumed importance of such nanocrystalline (NC) fault rock in controlling fault mechanical behavior, their prevalence and potential role in controlling natural earthquake cycles remains insufficiently investigated. In this contribution, we summarize the physical properties of NC materials that may have a profound effect on fault rheology, and we review the structural characteristics of NC PSZs observed in natural faults and in experiments. Numerous literature reports show that such zones form in a wide range of faulted rock types, under a wide range of conditions pertaining to seismic and a-seismic upper-crustal fault slip, and frequently show an internal crystallographic preferred orientation (CPO) and partial amorphization, as well as forming glossy or “mirror-like” slip surfaces. Given the widespread occurrence of NC PSZs in upper-crustal faults, we suggest that they are of general significance. Specifically, the generally high rates of (diffusion) creep in NC fault rock may play a key role in controlling the depth limits to the seismogenic zone.
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Gibson, Richard G. "Physical character and fluid-flow properties of sandstone-derived fault zones." Geological Society, London, Special Publications 127, no. 1 (1998): 83–97. http://dx.doi.org/10.1144/gsl.sp.1998.127.01.07.
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Guillou-Frottier, Laurent, Hugo Duwiquet, Gaëtan Launay, Audrey Taillefer, Vincent Roche, and Gaétan Link. "On the morphology and amplitude of 2D and 3D thermal anomalies induced by buoyancy-driven flow within and around fault zones." Solid Earth 11, no. 4 (August 26, 2020): 1571–95. http://dx.doi.org/10.5194/se-11-1571-2020.
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Abstract. In the first kilometers of the subsurface, temperature anomalies due to heat conduction processes rarely exceed 20–30 ∘C. When fault zones are sufficiently permeable, fluid flow may lead to much larger thermal anomalies, as evidenced by the emergence of thermal springs or by fault-related geothermal reservoirs. Hydrothermal convection triggered by buoyancy effects creates thermal anomalies whose morphology and amplitude are not well known, especially when depth- and time-dependent permeability is considered. Exploitation of shallow thermal anomalies for heat and power production partly depends on the volume and temperature of the hydrothermal reservoir. This study presents a non-exhaustive numerical investigation of fluid flow models within and around simplified fault zones, wherein realistic fluid and rock properties are accounted for, as are appropriate boundary conditions. 2D simplified models point out relevant physical mechanisms for geological problems, such as “thermal inheritance” or pulsating plumes. When permeability is increased, the classic “finger-like” upwellings evolve towards a “bulb-like” geometry, resulting in a large volume of hot fluid at shallow depth. In simplified 3D models wherein the fault zone dip angle and fault zone thickness are varied, the anomalously hot reservoir exhibits a kilometer-sized “hot air balloon” morphology or, when permeability is depth-dependent, a “funnel-shaped” geometry. For thick faults, the number of thermal anomalies increases but not the amplitude. The largest amplitude (up to 80–90 ∘C) is obtained for vertical fault zones. At the top of a vertical, 100 m wide fault zone, temperature anomalies greater than 30 ∘C may extend laterally over more than 1 km from the fault boundary. These preliminary results should motivate further geothermal investigations of more elaborated models wherein topography and fault intersections would be accounted for.
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Zoback, M., S. Hickman, and W. Ellsworth. "Scientific Drilling Into the San Andreas Fault Zone – An Overview of SAFOD's First Five Years." Scientific Drilling 11 (March 1, 2011): 14–28. http://dx.doi.org/10.5194/sd-11-14-2011.
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The San Andreas Fault Observatory at Depth (SAFOD) was drilled to study the physical and chemical processes controlling faulting and earthquake generation along an active, plate-bounding fault at depth. SAFOD is located near Parkfield, California and penetrates a section of the fault that is moving due to a combination of repeating microearthquakes and fault creep. Geophysical logs define the San Andreas Fault Zone to be relatively broad (~200 m), containing several discrete zones only 2–3 m wide that exhibit very low P- and S-wave velocities and low resistivity. Two of these zones have progressively deformed the cemented casing at measured depths of 3192 m and 3302 m. Cores from both deforming zones contain a pervasively sheared, cohesionless, foliated fault gouge that coincides with casing deformation and explains the observed extremely low seismic velocities and resistivity. These cores are being now extensively tested in laboratories around the world, and their composition, deformation mechanisms, physical properties, and rheological behavior are studied. Downhole measurements show that within 200 m (maximum) of the active fault trace, the direction of maximum horizontal stress remains at a high angle to the San Andreas Fault, consistent with other measurements. The results from the SAFOD Main Hole, together with the stress state determined in the Pilot Hole, are consistent with a strong crust/weak fault model of the San Andreas. Seismic instrumentation has been deployed to study physics of faulting – earthquake nucleation, propagation, and arrest – in order to test how laboratory-derived concepts scale up to earthquakes occurring in nature. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.11.02.2011" target="_blank">10.2204/iodp.sd.11.02.2011</a>
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Pampillón, Pedro, David Santillán, Juan Carlos Mosquera, and Luis Cueto-Felgueroso. "Geomechanical Constraints on Hydro-Seismicity: Tidal Forcing and Reservoir Operation." Water 12, no. 10 (September 29, 2020): 2724. http://dx.doi.org/10.3390/w12102724.
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Understanding the risk associated with anthropogenic earthquakes is essential in the development and management of engineering processes and hydraulic infrastructure that may alter pore pressures and stresses at depth. The possibility of earthquakes triggered by reservoir impoundment, ocean tides, and hydrological events at the Earth surface (hydro-seismicity) has been extensively debated. The link between induced seismicity and hydrological events is currently based on statistical correlations rather than on physical mechanisms. Here, we explore the geomechanical conditions that could allow for small pore pressure changes due to reservoir management and sea level changes to propagate to depths that are compatible with earthquake triggering at critically-stressed faults (several kilometers). We consider a damaged fault zone that is embedded in a poroelastic rock matrix, and conduct fully coupled hydromechanical simulations of pressure diffusion and rock deformation. We characterize the hydraulic and geomechanical properties of fault zones that could allow for small pressure and loading changes at the ground surface (in the order of tens or hundreds of kPa) to propagate with relatively small attenuation to seismogenic depths (up to 10 km). We find that pressure diffusion to such depths is only possible for highly permeable fault zones and/or strong poroelastic coupling.
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Fagereng, Å., and A. Beall. "Is complex fault zone behaviour a reflection of rheological heterogeneity?" Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 379, no. 2193 (February 2021): 20190421. http://dx.doi.org/10.1098/rsta.2019.0421.
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Fault slip speeds range from steady plate boundary creep through to earthquake slip. Geological descriptions of faults range from localized displacement on one or more discrete planes, through to distributed shearing flow in tabular zones of finite thickness, indicating a large range of possible strain rates in natural faults. We review geological observations and analyse numerical models of two-phase shear zones to discuss the degree and distribution of fault zone heterogeneity and effects on active fault slip style. There must be certain conditions that produce earthquakes, creep and slip at intermediate velocities. Because intermediate slip styles occur over large ranges in temperature, the controlling conditions must be effects of fault properties and/or other dynamic variables. We suggest that the ratio of bulk driving stress to frictional yield strength, and viscosity contrasts within the fault zone, are critical factors. While earthquake nucleation requires the frictional yield to be reached, steady viscous flow requires conditions far from the frictional yield. Intermediate slip speeds may arise when driving stress is sufficient to nucleate local frictional failure by stress amplification, or local frictional yield is lowered by fluid pressure, but such failure is spatially limited by surrounding shear zone stress heterogeneity. This article is part of a discussion meeting issue ‘Understanding earthquakes using the geological record’.
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Barnes, Philip M., Laura M. Wallace, Demian M. Saffer, Rebecca E. Bell, Michael B. Underwood, Ake Fagereng, Francesca Meneghini, et al. "Slow slip source characterized by lithological and geometric heterogeneity." Science Advances 6, no. 13 (March 2020): eaay3314. http://dx.doi.org/10.1126/sciadv.aay3314.
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Slow slip events (SSEs) accommodate a significant proportion of tectonic plate motion at subduction zones, yet little is known about the faults that actually host them. The shallow depth (<2 km) of well-documented SSEs at the Hikurangi subduction zone offshore New Zealand offers a unique opportunity to link geophysical imaging of the subduction zone with direct access to incoming material that represents the megathrust fault rocks hosting slow slip. Two recent International Ocean Discovery Program Expeditions sampled this incoming material before it is entrained immediately down-dip along the shallow plate interface. Drilling results, tied to regional seismic reflection images, reveal heterogeneous lithologies with highly variable physical properties entering the SSE source region. These observations suggest that SSEs and associated slow earthquake phenomena are promoted by lithological, mechanical, and frictional heterogeneity within the fault zone, enhanced by geometric complexity associated with subduction of rough crust.
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Seo, Yong Seok, Chang Yong Kim, Kwang Yeom Kim, and Kyoung Mi Lee. "Geomechanical Characterization of Faulted Rock Materials in Korea." Key Engineering Materials 321-323 (October 2006): 328–31. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.328.
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A faulted rock usually shows the swelling behavior because of clay minerals which consist of the fault gouges. It makes rock mass unstable and threatens the safety of structures built in rock mass. This study was aimed at clarifying characteristics of physical and mechanical properties of faulted rock materials. At first, microstructures and mineralogical composition associated with faulting in the fault gouge zones were analyzed by using X-ray diffractometry (XRD) and SEM microphotographs. Physical properties of the faulted rock materials from fields were measured in the laboratory. It is well known that the mechanical properties are sensitive to the mineralogical assemblage and are affected by the shapes, distribution and preferred crystallographic orientation of the components. Material and direct shear tests were also conducted on faulted rock materials under saturated and unsaturated conditions. The mechanical results were analyzed together with the analyzed result of XRD and SEM.
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Kassym, A. E., V. S. Portnov, M. B. Mynbayev, N. S. Askarova, and А. N. Yessendossova. "Criteria and signs of lead-zinc mineralization within the Maityubinsky anticlinorium." Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 330, no. 3 (December 7, 2023): 68–75. http://dx.doi.org/10.31643/2024/6445.30.
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The paper presents research work to establish genetic characteristics of lead-zinc mineralization in the Ulytau-Arganatinsky structural-facial zone. Expanding the mineral resource base of Central Kazakhstan is one of the most urgent tasks because selecting the criteria and characteristics determines the aspects of prospecting and exploration work, as well as their results, which is the goal. In this regard, the following tasks are being solved: identifying the geodynamic position, the genesis of mineralization, the connection of the rock's physical properties with geophysical anomalies, as well as displaying tectonic disturbances and deep faults in them; establishing the connection of mineralization with the carbonaceous-terrigenous package of deposits of the lower subformation of the Zhilandinsky formation of the Upper Proterozoic; structural confinement of mineralization to large faults along which there was a movement of plutogenic hydrothermal solutions forming mineralization, and areas of metamorphically altered rocks, as well as aureole zones of Pb, Zn, Ag, Cd graphite quartz, phyllites and the other shales of the Zhilandysay and Kumolinsky formations, dispersion zones of Cu, Mo, V, Ag, Sc, Ye and REE near the Kyzymchek fault. The established criteria and features can be used when organizing geological exploration work in the search for polymetallic mineralization within the Maityubinsky anticlinorium in zones adjacent to deep mantle faults.
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Zhu, Danping, Xuewei Liu, and Shaobin Guo. "Reservoir Formation Model and Main Controlling Factors of the Carboniferous Volcanic Reservoir in the Hong-Che Fault Zone, Junggar Basin." Energies 13, no. 22 (November 21, 2020): 6114. http://dx.doi.org/10.3390/en13226114.
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The Hong-Che Fault Zone is one of the important oil and gas enrichment zones in the Junggar Basin, especially in the Carboniferous. In recent five years, it has been proven that the Carboniferous volcanic rock has 140 million tons of oil reserves, and has built the Carboniferous volcanic reservoir with a capacity of million tons. Practice has proven that the volcanic rocks in this area have great potential for oil and gas exploration and development. To date, Carboniferous volcanic reservoirs have been discovered in well areas such as Che 32, Che 47, Che 91, Chefeng 3, Che 210, and Che 471. The study of drilling, logging, and seismic data shows that the Carboniferous volcanic reservoirs in the Hong-Che Fault Zone are mainly distributed in the hanging wall of the fault zone, and oil and gas have mainly accumulated in the high part of the structure. The reservoirs are controlled by faults and lithofacies in the plane and are vertically distributed within 400 m from the top of the Carboniferous. The Carboniferous of the Hong-Che Fault Zone has experienced weathering leaching and has developed a weathering crust. The vertical zonation characteristics of the weathering crust at the top of the Carboniferous in the area of the Che 210 well are obvious. The soil layer, leached zone, disintegration zone, and parent rock developed from top to bottom. Among these reservoirs, the reservoirs with the best physical properties are mainly developed in the leached zone. Based on a comprehensive analysis of the Carboniferous oil and gas reservoirs in areas of the Chefeng 3 and Che 210 wells, it is believed that the formation of volcanic reservoirs in the Hong-Che Fault Zone was mainly controlled by structures and was also controlled by lithofacies, unconformity surfaces, and physical properties.
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Wenning, Quinn C., Claudio Madonna, Antoine de Haller, and Jean-Pierre Burg. "Permeability and seismic velocity anisotropy across a ductile–brittle fault zone in crystalline rock." Solid Earth 9, no. 3 (May 29, 2018): 683–98. http://dx.doi.org/10.5194/se-9-683-2018.
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Abstract. This study characterizes the elastic and fluid flow properties systematically across a ductile–brittle fault zone in crystalline rock at the Grimsel Test Site underground research laboratory. Anisotropic seismic velocities and permeability measured every 0.1 m in the 0.7 m across the transition zone from the host Grimsel granodiorite to the mylonitic core show that foliation-parallel P- and S-wave velocities systematically increase from the host rock towards the mylonitic core, while permeability is reduced nearest to the mylonitic core. The results suggest that although brittle deformation has persisted in the recent evolution, antecedent ductile fabric continues to control the matrix elastic and fluid flow properties outside the mylonitic core. The juxtaposition of the ductile strain zone next to the brittle zone, which is bounded inside the two mylonitic cores, causes a significant elastic, mechanical, and fluid flow heterogeneity, which has important implications for crustal deformation and fluid flow and for the exploitation and use of geothermal energy and geologic waste storage. The results illustrate how physical characteristics of faults in crystalline rocks change in fault zones during the ductile to brittle transitions.
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Géraud, Yves, Michel Rosener, Fabrice Surma, Joachim Place, Édouard Le Garzic, and Marc Diraison. "Physical properties of fault zones within a granite body: Example of the Soultz-sous-Forêts geothermal site." Comptes Rendus Geoscience 342, no. 7-8 (July 2010): 566–74. http://dx.doi.org/10.1016/j.crte.2010.02.002.
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Wang, Li, Shao Hua Li, and Jun Li. "Application of Fault Zone Modeling." Advanced Materials Research 807-809 (September 2013): 2188–91. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.2188.
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In outcrops, a fault often appears to be a geologic body with some volume which is called as a fault zone. In the geologic modeling, a fault is often characterized as a surface which cannot characterize the inner structures of the fault zone and the physical differences led by different clast fillings in the fault zone. So, a new method of fault zone modeling was applied in Weizhou oilfield, the proposed method was as follows: First, the two boundaries of a fault zone were characterized as two surfaces, and the distance between the two surfaces was decided by the extent of the fault zone, and the area between the two boundary surfaces was the fault zone. Second, fault zone could be divided into several parts which would characterize its inner structures and properties. When the fault zone is characterized as a geologic body, its inner structures and properties such as its closure can be characterized, which can provide a geologic model that is closer to the actual for the post numerical reservoir simulation.
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Crespo, E., J. Luque, J. F. Barrenechea, and M. Rodas. "Mechanical graphite transport in fault zones and the formation of graphite veins." Mineralogical Magazine 69, no. 4 (August 2005): 463–70. http://dx.doi.org/10.1180/0026461056940266.
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AbstractThis paper describes a vein-shaped graphite occurrence in which, for the first time, the geological, mineralogical and isotopic evidence support its formation by physical remobilization of previously formed syngenetic graphite. The deposit studied is located in the Spanish Central System and it occurs along the contact between a hydrothermal Ag-bearing quartz vein and a graphite-bearing quartzite layer. The characteristics of this occurrence differ from those of fluid-deposited vein-type graphite mineralization in that: (1) graphite flakes are oriented parallel to the vein walls; (2) graphite crystallinity is slightly lower than in the syngenetic precursor (graphite disseminated in the quartzite); and (3) the isotopic signatures of both types of graphite are identical and correspond to biogenic carbon. In addition, the P-T conditions of the hydrothermal Ag-bearing quartz veins in the study area (P <1 kbar, and T up to 360°C) contrast with the high degree of structural order of graphite in the vein. Therefore, physical remobilization of graphite can be regarded as a suitable alternative mechanism to account for some cases of vein-shaped graphite deposits. Such a mechanism would require a previous concentration of disseminated syngenetic graphite promoted, in this case, by the retrograde solubility of quartz. This process would generate monomineralic graphite aggregates enhancing its lubricant properties and permitting graphite to move in the solid state along distances in the range of up to several metres.
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Yosifov, D., B. Maneva, A. Tsvetkov, and V. Pchelarov. "Geotectonic position and structure of Spahievo ore field." Geologica Balcanica 20, no. 1 (February 28, 1990): 45–65. http://dx.doi.org/10.52321/geolbalc.20.1.45.
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Based on analysis of the physical parameters of rocks and the distribution of geophysical fields, many new data on the structure and geotectonic position of Spahievo ore field were obtained. A complex of geological and geophysical information was interpreted using physicogeological modelling. The results show that the tectonic position of the ore field is controlled mainly by the deep-seated Ardino-Spahievo and Novakovo-Pilaševo fault zones and the Momcilgrad-Spahievoregional fault. The tectonic knot, formed at their intersection, is a source structure marked by concentration of intensive magnetic anomalies of different sign. A large part of these anomalies are related to abundant comagmatic bodies both exposed on the surface (Sârnica, Mezarlâksârt, Pilaševo, Karaman) and cryptointrusive (Garno Bryastovo, Susam, Ramadan). Their magnetic properties enable to evaluate the depth, form and sometimes the approximate composition of the bodies. The area studied shows a block-disintegrated and faulted pre-Paleogene basement, dipping westsouthwest towards Borovica Depression. Depending on the distribution of the geophysical fields, the structural, magmatic and metallogenic features, three large mesoblocks may be divided: Borovica (I), Pilaševo (II) and Sârnica (Ill). Each mesoblock contains characteristic mineralization – rare-metal, gold-polymetallic and polymetallic, respectively. The 1ead-zinc ore mineralizations are related to an uplifted block of the basement, located in the central part of the eastern segment and formed by the intersection of Ardino-Spahievo and Novakovo-Pilaševo deep-seated fault zones. The knot areas of the regional deep zones control the origin of polyformational mineralization.
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Shtohryn, Liudmyla. "GEODYNAMICS." GEODYNAMICS 1(30)2021, no. 1(30) (June 29, 2021): 65–77. http://dx.doi.org/10.23939/jgd2021.01.065.
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Purpose. The aim of the research presented in this article is to analyze the features of the reflection of the damage to the territory of the Transcarpathian region by landslide processes based on the anomalies in the magnetic and gravitational fields, taking into account tectonic zoning. The study is an important stage in predicting the landslide processes and it is aimed at reducing their negative effects on the environment. The relevance of the research is due to the growing intensification of landslides in the Carpathian region of Ukraine. Methodology. The development of landslides in each structural-tectonic zone is associated with its tectonic structure, and therefore these processes can have different intensity, dynamics, tendencies for further development and distribution area. Lithological-facies composition and bedding conditions of rocks form the physical and mechanical properties of rocks, determining the rate and mechanism of the development of landslides. The spatial confinedness of landslide processes in the fault zones is reflected in the gravitational and magnetic fields. Results. With the help of GIS MapInfo tools, a number of landslides in each tectonic zone, anomalies in the gravitational and magnetic fields, areas affected by landslides, the distance to the fault zones were calculated. The important result of the research is to prove a direct correlation between the spatial distribution of landslides and fault zones, tectonic structure, the lithological composition of rocks, which are reflected in gravimagnetic anomalies. Scientific novelty. The peculiarities of the reflection of the tectonic structure, zones of decompression, fragmentation of rocks and lithological composition in gravimagnetic fields on a regional scale are examined, and their association with landslide processes is evaluated for the first time. Practical significance. The theoretical substantiation of the peculiarities of the behaviour of gravimagnetic fields in the zones of distribution of landslide processes makes it possible to assess the natural conditions for the formation and development of landslides in a given region. The connection between the impact of the fault zones on landslide processes by their reflection in gravimagnetic fields is established, which can be used in the future for spatial forecasting of the development of landslides in territories with related structural-tectonic conditions.
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Al-Jawad, Mohammed Saleh, and Khalid Ahmed Kareem. "Geological Model of Khasib Reservoir- Central Area/East Baghdad Field." Iraqi Journal of Chemical and Petroleum Engineering 17, no. 3 (September 30, 2016): 1–10. http://dx.doi.org/10.31699/ijcpe.2016.3.1.
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The Geological modeling has been constructed by using Petrel E&P software to incorporate data, for improved Three-dimensional models of porosity model, water saturation, permeability estimated from core data, well log interpretation, and fault analysis modeling.
Three-dimensional geological models attributed with physical properties constructed from primary geological data. The reservoir contains a huge hydrocarbon accumulation, a unique geological model characterization with faults, high heterogeneity, and a very complex field in nature.
The results of this study show that the Three-dimensional geological model of Khasib reservoir, to build the reservoir model starting with evaluation of reservoir to interpretation of well log by using IP software for 14 wells, defining and divided the layers based on the GR Log and Resistivity log to nine layers and then maintained the fault model for a divided central area to four regions. Compared porosity log with porosity core to estimate correction porosity and enter this value to predict the permeability value for each layer by using FZI, and RQI method. The model Containing faults, horizons, zones, and layers depending on this data to make gridding by using pillar gridding.
This paper presents a geological modeling and an uncertainty analysis for stock-tank original oil in place. The distribution of the faults is also discussed.
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Jiménez-Espinosa, Rosario, Pilar Hernández-Puentes, and Juan Jiménez-Millán. "Water–Rock Interaction Processes in Tíscar and Larva Active Faults (Betic Cordillera, SE Spain)." Water 16, no. 6 (March 20, 2024): 897. http://dx.doi.org/10.3390/w16060897.
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A hydrochemical and mineral study of groundwaters and damaged rocks from the Tíscar and Larva fault zones (Betic Cordillera, Iberian Peninsula) was carried out in order to (a) describe the physical and chemical properties of the groundwaters; (b) recognize significant locations with deep-origin fluids related to active tectonics; (c) and to describe the water–rock interaction and the neoformation of clay mineral processes and their importance in the seismicity of the faults. A sampling campaign was completed between November 2012 and November 2013, during which data were obtained from 23 different groundwater sites in the fault areas. Two main groups of waters were distinguished: (a) Ca2+-Mg2+-HCO3− facies characterized by poor conductivity and salinity; and (b) saline waters (up to 30 meq/L) rich in Ca2+-Mg2+-SO4-Cl− and with an elevated conductivity (frequently > 1000 μS/cm). In addition, a minor group of saline and warm waters (T > 16.5 °C) was found to be Na+-rich and show moderately high B values (>0.33 ppm), and which mig ht be hosted in aquifers deeper than the two main groups. This group of deep-origin waters is oversaturated in clay minerals and is in equilibrium for Ca-Mg carbonate minerals. X-ray diffraction and scanning and transmission electron microscopy data corroborate the crystallization forecast of authigenic smectite, which appears as thin films coating carbonate fragments. The origin of smectite is related to the fragile strain and thermal–fluid–mineral interactions in fault rocks. Smectite could lubricate carbonate rocks, which favor creep deformation versus seismic slip. This work provides locations where groundwater physico-chemical properties and composition suggest tectonic fault activity.
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Skalbeck, John D., Robert E. Karlin, Lisa Shevenell, and Michael C. Widmer. "Gravity and aeromagnetic modeling of alluvial basins in the southern Truckee Meadows adjacent to the Steamboat Hills geothermal area, Washoe County, Nevada." GEOPHYSICS 70, no. 3 (May 2005): B1—B9. http://dx.doi.org/10.1190/1.1925739.
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The concurrent development of the Steamboat Hills geothermal area for power production and the adjacent alluvial aquifers for drinking water in Washoe County, Nevada, necessitates a good understanding of the hydrogeologic connection between these water resources. The problem is that adequate characterization of the subsurface geologic structure is not possible with existing geologic data. This need prompted us to construct a detailed 3D representation of the subsurface geologic structure based on 2.75D forward modeling of 11 gravity and aeromagnetic profiles constrained by geologic data and physical (density, magnetic susceptibility, remanent magnetic) properties. Potential-fields modeling results provided greater definition of the alluvial basins, and when combined with well-log data, yield an overall basin volume surrounding Steamboat Hills that is 64% greater than the volume derived from well-log data alone. A representation of the geothermal reservoir, consisting of altered granodiorite and metamorphic rocks, illustrates that the flow of thermal water is fault controlled. The model also suggests that thermal water may upflow along an unexplored fault flanking western Steamboat Hills. North-trending faults that conduct thermal water from the geothermal system to the alluvial aquifer appear to be zones of altered volcanics that produce subtle aeromagnetic anomalies.
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Panteleev, I. A., V. I. Okunev, and V. A. Novikov. "Synchronization of multifractal properties of continuous acoustic emission during the preparation and implementation of dynamic slip in model fault." Geosystems of Transition Zones 7, no. 4 (2023): 405–18. http://dx.doi.org/10.30730/gtrz.2023.7.4.405-418.
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According to the stick-slip model, the relative movement of the fault planes is an act of unstable sliding, where movement begins when the stresses tangential to the fault plane reach a certain limit. The physical mechanism of dynamic slip along a fault consists of the sequential formation of conglomerates of loaded particles (force chains) in the contact zone and their subsequent destruction. These chains together form a force skeleton characterized by a specific spatial structure and strength properties. An increase in shear stress on the fault banks leads to local destruction of the strength skeleton; further evolution of the system brings destruction processes to higher spatial levels, ultimately leading to a shift in the fault banks. Since the evolution of the process of destruction of force chains in the contact zone of a fault along the hierarchy of scales from bottom to top is similar to the evolution of crack formation in a loaded medium from microscale to macroscale (specimen scale), the authors hypothesized the coherent behavior of acoustic noise accompanying the preparation of dynamic slip and recorded in different areas of fault zones. This work is devoted to testing this hypothesis on a laboratory scale, using an installation that simulates movement along a fault. As a result of the analysis, the hypothesis about the synchronization of the statistical properties of the acoustic emission during the preparation and implementation of the dynamic movement was confirmed. It is shown that the observation (detection) of the effect of the synchronization of the statistical properties of acoustic emission depends both on the set of parameters for which the spectral coherence measure is calculated and on the location of the recording of the initial data.
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Podugu, Nagaraju, Satrughna Mishra, Thomas Wiersberg, and Sukanta Roy. "Chemical and Noble Gas Isotope Compositions of Formation Gases from a 3 km Deep Scientific Borehole in the Koyna Seismogenic Zone, Western India." Geofluids 2019 (September 17, 2019): 1–16. http://dx.doi.org/10.1155/2019/1078942.
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A 3 km deep research borehole KFD1 was drilled in the Koyna reservoir-triggered seismicity region, Western India, between December 2016 and May 2017. The 1967 M 6.3 Koyna earthquake had generated a NNE-SSW trending surface fissure zone in the Nanel-Donichawadi-Kadoli sector. KFD1 is located ~5 km south of Kadoli along the trend of the Donichawadi fault zone. Online gas monitoring was carried out during drilling of KFD1 from 1315 m to 2831 m depth to sample and study the composition of crustal gases. Formation gases CO2, CH4, H2, and He were only observed during water flushing of ~100 m intervals following coring runs. Laboratory analyses of gas samples collected between 1737 m and 2831 m depth revealed concentrations of up to 1200 ppmv CO2, 186 ppmv CH4, 139 ppmv H2, and 12.8 ppmv He. Zones enriched in gases are mostly below the 2100 m depth with significant He enhancement ranging from 4.6 to 7.6 ppmv above the atmospheric value. The He-rich zones correlate well with the zones of anomalous physical and mechanical properties identified from geophysical logs and are characterized by high fracture density as revealed from borehole images, indicating that the borehole punctured multiple fracture zones. The helium concentrations are consistent with those previously observed over the surface fissures near Kadoli, suggesting a southward extension of the Donichawadi fault zone up to the KFD1 site and confirming that the fault zone is permeable even after 50 years of the 1967 Koyna earthquake. 3He/4He ratios of eleven gas samples fall between 0.426±0.022 and 0.912±0.059 Ra, with 4He/20Ne values between 0.3449±0.0091 and 0.751±0.020. Air-corrected helium isotope ratios indicate that helium is a mixture of atmospheric and crustal radiogenic components but no mantle contribution within 2σ analytical uncertainties.
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Zhu, Xiaomin, Shunli Li, Qianghu Liu, Zili Zhang, Changgui Xu, Xiaofeng Du, Huiyong Li, and Wenlong Shi. "Source to sink studies between the Shaleitian uplift and surrounding sags: Perspectives on the importance of hinterland relief and catchment area for sediment budget, Western Bohai Bay Basin, China." Interpretation 5, no. 4 (November 30, 2017): ST65—ST84. http://dx.doi.org/10.1190/int-2017-0027.1.
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Source-to-sink system analysis, a cutting-edge topic in the field of earth science, encompasses the whole system, from erosion and transportation to sediment accumulation on the earth’s surface, and involves multidisciplinary collaboration. This current analysis, based on high-precision 3D seismic data, well logs, and other drilling data, using quantitative characterization of the source-to-sink elements, documents that Archean-Proterozoic migmatitic granite, Cambrian-Ordovician carbonate and clastic rocks, and Mesozoic volcaniclastic rocks are developed in the Shaleitian uplift from south to north across large relief differences (up to 2300 m). The relief and size of the catchment in the source area were calculated by denudation recovery, time-depth conversion and high-resolution interpretation on seismic data. Three types of sediment-transporting channel system and 20 catchment areas ([Formula: see text]) were documented around the edges of the uplift: paleovalley channels, fault-controlled channels, and fault-transfer channels. The Paleogene sink is dominated by near-source coarse-grained depositional systems, with the lithofacies characteristics of low lake level (sand rich), lake transgressive (mud rich), and uplift period (sand rich). Three types of boundary conditions developed in the region of the Shaleitian uplift: fault-related steep-slopes (single or multiple), fault ramps, and slope patterns. The bedrock composition, catchment area, channel systems, and fault-border patterns in the Shaleitian uplift jointly controlled the types and scales of sedimentary sandbodies. The south Shaleitian tectonic zone functioned as a high-efficiency coupling system in which reservoir sandbodies were developed (extensive length distance, with well-sorted and round-grained sediments, but weak physical properties). The coupling system for the southwest and west Shaleitian tectonic zones is subordinate (near source and sand rich, sand and mud interbedded, and weak physical properties). The coupling system of the northeast Shaleitian tectonic zone is lowest in efficiency (relatively mud rich).
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Murakami, Sota, Tsuyoshi Ichimura, Kohei Fujita, Takane Hori, and Yusaku Ohta. "Impact of Ambiguity of Physical Properties of Three-Dimensional Crustal Structure Model on Coseismic Slip and Interseismic Slip Deficit in the Nankai Trough Region." GeoHazards 3, no. 2 (April 6, 2022): 162–77. http://dx.doi.org/10.3390/geohazards3020009.
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Since huge earthquakes are expected along plate subduction zones such as the Japan Trench and Nankai Trough, the estimation of coseismic slip and interseismic slip deficit is essential for immediate response and preliminary measures to reduce damage. Recently, analysis considering the complex topography and underground structure of the plate subduction zone has been performed for improving the estimation performance. However, the three-dimensional (3D) crustal structural model needs to be improved continuously. In this paper, we obtained Green’s functions for 3D crustal structural models with ambiguity by 3D crustal deformation analysis, and the coseismic slip and interseismic slip deficit were estimated. Here we enabled the calculation of many Green’s functions with different physical properties of the 3D crustal structure by utilizing a GPU-based 3D crustal deformation analysis method that significantly reduces the analysis cost. The physical properties on the upper plate’s side, which are located above the plate boundary fault, were changed. We found no significant difference in the estimation performance, except for the upper crust, which most of the fault slip area is in contact with, in the case of coseismic slip estimation. In contrast, the coseismic slip estimation when the properties of the upper crust was changed had a significant error, and a negative slip was estimated at the deep part of the plate boundary where no slip was originally given.
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Wu, Shizhong. "Optimization Method for PDC Drill Bits in Hechuan." International Journal of Energy 3, no. 2 (October 1, 2023): 77–80. http://dx.doi.org/10.54097/ije.v3i2.018.
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The Hechuan region is located in the eastern part of the Sichuan Basin, with extremely complex crustal structures, including geological structures such as fault zones and fold zones. In the Hechuan area, the geological conditions are diverse and complex, including volcanic rocks, sedimentary rocks, metamorphic rocks, etc. The physical properties and strength of these formations vary, posing great challenges for drilling operations. In order to improve drilling efficiency, it is necessary to optimize the type of PDC bit. Firstly, the rock breaking principle of PDC drill bits was elaborated. Secondly, we optimize PDC drill bits based on their drillability, rock drillability, and compressive strength. Through the comprehensive analysis of the above three methods, the suitable types of PDC drill bits for the Hechuan area of the Sichuan Basin can be determined. According to the complexity of geological conditions and the different properties of rocks, PDC bits with strong adaptability, high wear resistance and impact resistance, strong cutting ability and guidance can be selected to improve drilling efficiency and reduce drilling costs.
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Farough, Aida, and Alexander K. Karrasch. "Correlation of Elastic Moduli and Serpentine Content in Ultramafic Rocks." Geosciences 9, no. 12 (November 25, 2019): 494. http://dx.doi.org/10.3390/geosciences9120494.
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Understanding the physical properties of ultramafic rocks is important for evaluating a wide variety of petrologic models of the oceanic lithosphere, particularly upper mantle and lower crust. Hydration of oceanic peridotites results in increasing serpentine content, which affects lithospheric physical properties and the global bio/geochemical cycles of various elements. In understanding tectonic, magmatic, and metamorphic history of the oceanic crust, interpreting seismic velocities, rock composition, and elastic moduli are of fundamental importance. In this study, we show that as serpentine content increases, density decreases linearly with a slope of 7.85. Porosity of the samples does not show any systematic correlation with serpentine content, as it is more strongly affected by local weathering and erosional processes. We also correlate increase in serpentine content with a linear decline in shear, bulk, and Young’s moduli with slopes of 0.48, 0.77, and 0.45, respectively. Our results show that increase in serpentine content of mantle wedge and forearc mantle contributes to their brittle behavior and result in break-offs, obduction, and overthrusting. Therefore, serpentine content strongly affects tectonic processes at subduction zones, particularly serpentinization may be responsible for formation of weak fault zones. Also, serpentinization of fresh oceanic peridotite in slow and ultra-slow spreading ridges may be responsible for observed discontinuities in thin crust.
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Guseltsev, А. S. "Definition of weakened zones from the standpoint of engineering geology and hydrogeology." Proceedings of higher educational establishments. Geology and Exploration, no. 4 (December 8, 2023): 89–96. http://dx.doi.org/10.32454/0016-7762-2023-65-4-89-96.
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Background. In recent decades, the concept of weakened zones has become widespread in various fields of Earth science. Thus, this concept is currently used in geology, mining, geomechanics, tectonics, geodynamics, and seismology. As a result, weakened zones can be considered and interpreted both as large fault zones, including dilatancy zones, and zones with sharply or quite noticeably changing physical and mechanical properties. At the same time, the purpose of studying and recording such zones also changes, depending on particular research tasks.Aim. To consider structures that are widely termed as weakened zones, although having received no clear definition and classification. To provide a definition of this term from the standpoint of hydrogeology and engineering geology.Materials and methods. The research basis was formed by the author’s long-term experience in the selection of sites for the location of nuclear energy facilities. The main methods included collection, generalization, and processing of information obtained by the author during fieldwork and laboratory research.Results. The author considers structures that are termed as weakened zones in Earth sciences, concerning a fairly wide range of structures and conditions of mountain ranges and soils. A definition of a weakened zone from the standpoint of hydrogeology and engineering geology is proposed. Various factors indicating the presence of weakened zones and possible negative consequences for engineering structures are considered.Conclusion. The concept of weakened zones should be taken into consideration when conducting detailed surveys of areas for the location of engineering facilities. It is noted that, when carrying out detailed surveys, the key to quantifying the characteristics of weakened zones in dispersed soils consists in a correct assessment of the spatial variability of soil parameters, largely the density of dry soil and porosity.
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Hung, Jih-Hao, Yun-Hao Wu, En-Chao Yeh, Jong-Chang Wu, and TCDP Scientific Party. "Subsurface Structure, Physical Properties, and Fault Zone Characteristics in the Scientific Drill Holes of Taiwan Chelungpu-Fault Drilling Project." Terrestrial, Atmospheric and Oceanic Sciences 18, no. 2 (2007): 271. http://dx.doi.org/10.3319/tao.2007.18.2.271(tcdp).
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Solum, J. G., S. Hickman, D. A. Lockner, S. Tembe, J. Pl Evans, S. D. Draper, D. C. Barton, et al. "San Andreas Fault Zone Mineralogy, Geochemistry, and Physical Properties from SAFOD Cuttings and Core." Scientific Drilling SpecialIssue (November 1, 2007): 64–67. http://dx.doi.org/10.5194/sd-specialissue-64-2007.
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Shipton, Z. K., J. J. Roberts, E. L. Comrie, Y. Kremer, R. J. Lunn, and J. S. Caine. "Fault fictions: systematic biases in the conceptualization of fault-zone architecture." Geological Society, London, Special Publications 496, no. 1 (September 10, 2019): 125–43. http://dx.doi.org/10.1144/sp496-2018-161.
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AbstractMental models are a human's internal representation of the real world and have an important role in the way we understand and reason about uncertainties, explore potential options and make decisions. Mental models have not yet received much attention in geosciences, yet systematic biases can affect any geological investigation: from how the problem is conceived, through selection of appropriate hypotheses and data collection/processing methods, to the conceptualization and communication of results. We draw on findings from cognitive science and system dynamics, with knowledge and experiences of field geology, to consider the limitations and biases presented by mental models in geoscience, and their effect on predictions of the physical properties of faults in particular. We highlight biases specific to geological investigations and propose strategies for debiasing. Doing so will enhance how multiple data sources can be brought together, and minimize controllable geological uncertainty to develop more robust geological models. Critically, there is a need for standardized procedures that guard against biases, permitting data from multiple studies to be combined and communication of assumptions to be made. While we use faults to illustrate potential biases in mental models and the implications of these biases, our findings can be applied across the geosciences.
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Hung, Jih-Hao, Kuo-Fong Ma, Chien-Yin Wang, Hisao Ito, Weiren Lin, and En-Chao Yeh. "Subsurface structure, physical properties, fault-zone characteristics and stress state in scientific drill holes of Taiwan Chelungpu Fault Drilling Project." Tectonophysics 466, no. 3-4 (March 2009): 307–21. http://dx.doi.org/10.1016/j.tecto.2007.11.014.
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Ryashchenko, T. G., E. A. Maslov, E. V. Bryzhak, and S. I. Shtel’makh. "An engineering-geological study of rock soils and the products of their fracture zones (Albazinskoe deposit, north Khabarovsk Krai)." Proceedings of higher educational establishments. Geology and Exploration, no. 2 (October 17, 2022): 68–79. http://dx.doi.org/10.32454/0016-7762-2022-64-2-68-79.
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Background. The results of an engineering-geological study of rock soils and the products of their fault zones are considered on the example of samples selected in the sides of the Albazinskoe gold-bearing deposit located in the north of the Khabarovsk Krai.Aim. To develop and implement a methodological approach, which includes laboratory determinations of the velocity of propagation of longitudinal seismic waves (“seismic speed”) using a “Pulsar-2.2” unit (methods of continuous and through sounding), as well as density, porosity and water absorption determinations along with obtaining information about the types of microstructure and microtexture, the mineral composition and mineral alteration features under the influence of metamorphism (using petrographical thin sections).Materials and methods. For the collected rock soil samples the relationship between seismic velocity and physical properties indicators was evaluated (R-type cluster analysis programme). The products of fractural zones were studied in a laboratory according to a specially-developed methodological approach: extended (black clay) and reduced (crushed stone formations with debris). The microelement composition of the clay and gravel of argillites was determined for the first time, and the level of their pollution by toxic microelements (Zc index) was evaluated.Results. On the basis of quantitative assessment of the relationship between indicators of rocky soils various properties identified using the cluster analysis program, an “anomalous” conclusion is obtained about the absence of the rock soil density effect on seismic properties, which can be explained by the textural and structural features, as well as by mineral composition and the consequences of metamorphism (cataclastic and blastogenetic features recorded on the microscale in thin sections).Conclusion. The proposed methodological approach can be recommended for further studies of seismic, strength and physical properties of rocky soils during seismological and engineering-seismological studies of various territories.
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Yu, Zhang, Zhang Yan, and Mei Song-hua. "Experimental investigation on creep behavior of clastic rock." E3S Web of Conferences 165 (2020): 03051. http://dx.doi.org/10.1051/e3sconf/202016503051.
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Many deflected fault zones exist under the dam foundation Xiang-jiaba Hydropower Station in southwestern China. Clastic rock is the main medium with poor physical and mechanical properties. In or-der to study the creep properties of the clastic rock, triaxial compression creep experiments were carried out on a rock servo-controlling rheology testing machine. From the test results, it can be concluded that the clastic rock has obvious creep characteristics, and the time-dependent deformation is large. Based on the test results, the relationship between axial strain and time under different confining pressures is studied. The relationship between axial strain rates and deviatoric stress under different stress levels is also discussed in de-tail. Furthermore, the creep failure mechanism under different confining pressures is analyzed as well. Therefore, the creep law of the clastic rock specimen is gained. The relationship between the Burgers creep model and its parameters is obtained by fitting the creep curve with Burgers creep model. The result shows that Burgers model can accurately describe the creep properties of the clastic rock in Xiang-jiaba Hydro-power Project.
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Petley-Ragan, Arianne, Yehuda Ben-Zion, Håkon Austrheim, Benoit Ildefonse, François Renard, and Bjørn Jamtveit. "Dynamic earthquake rupture in the lower crust." Science Advances 5, no. 7 (July 2019): eaaw0913. http://dx.doi.org/10.1126/sciadv.aaw0913.
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Earthquakes in the continental crust commonly occur in the upper 15 to 20 km. Recent studies demonstrate that earthquakes also occur in the lower crust of collision zones and play a key role in metamorphic processes that modify its physical properties. However, details of the failure process and sequence of events that lead to seismic slip in the lower crust remain uncertain. Here, we present observations of a fault zone from the Bergen Arcs, western Norway, which constrain the deformation processes of lower crustal earthquakes. We show that seismic slip and associated melting are preceded by fracturing, asymmetric fragmentation, and comminution of the wall rock caused by a dynamically propagating rupture. The succession of deformation processes reported here emphasize brittle failure mechanisms in a portion of the crust that until recently was assumed to be characterized by ductile deformation.
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Qiong, WU, LI HaiBing, CHEVALIER Marie-Luce, MI GuiLong, LI Chao, HE XiangLi, and LI YaLin. "Rock characteristics, internal structure and physical-chemical properties of Qianning segment in Xianshuihe fault zone." Acta Petrologica Sinica 37, no. 10 (2021): 3204–24. http://dx.doi.org/10.18654/1000-0569/2021.10.14.
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Rempe, Marieke, Thomas M. Mitchell, Jörg Renner, Steven A. F. Smith, Andrea Bistacchi, and Giulio Di Toro. "The Relationship Between Microfracture Damage and the Physical Properties of Fault-Related Rocks: The Gole Larghe Fault Zone, Italian Southern Alps." Journal of Geophysical Research: Solid Earth 123, no. 9 (September 2018): 7661–87. http://dx.doi.org/10.1029/2018jb015900.
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Dyakov, Andrey, and Anatolii Kalashnik. "Influence of the rock massif physical properties variability on the localization of its disturbances with GPR." E3S Web of Conferences 498 (2024): 03012. http://dx.doi.org/10.1051/e3sconf/202449803012.
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An integrated approach to studying the influence of the physical properties of a rock mass on the localization of its disturbances by GPR sounding is considered. The performed studies have established that, during GPR sounding of rock masses, there is a distortion of the induced electromagnetic field in areas with different physical properties of rocks (such as: massif heterogeneity, rock fracturing, zones of increased water saturation, etc.). Regularities in the formation of wave patterns of GPR model data (changes in the in-phase axes and amplitude characteristics of the signal) of a rock mass containing structural inhomogeneities are revealed. During GPR sounding of such a rock mass, reflections from the edge parts of inhomogeneities appear in the wave patterns in the form of branches of hyperbolas. The intensity of the wave field distortion is determined by the contrast of the physical properties of rocks, as well as the spatial orientation and depth of heterogeneities, which is a key parameter of GPR sounding. It has been established that the variability of the physical properties of rocks in a rock mass near faults introduces significant distortions in the parameters determined by GPR sounding, including the angle of incidence of faults.
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Öncel, A. O., Ö. Alptekin, and I. Main. "Temporal variations of the fractal properties of seismicity in the western part of the north Anatolian fault zone: possible artifacts due to improvements in station coverage." Nonlinear Processes in Geophysics 2, no. 3/4 (December 31, 1995): 147–57. http://dx.doi.org/10.5194/npg-2-147-1995.
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Abstract. Seismically-active fault zones are complex natural systems exhibiting scale-invariant or fractal correlation between earthquakes in space and time, and a power-law scaling of fault length or earthquake source dimension consistent with the exponent b of the Gutenberg-Richter frequency-magnitude relation. The fractal dimension of seismicity is a measure of the degree of both the heterogeneity of the process (whether fixed or self-generated) and the clustering of seismic activity. Temporal variations of the b-value and the two-point fractal (correlation) dimension Dc have been related to the preparation process for natural earthquakes and rock fracture in the laboratory These statistical scaling properties of seismicity may therefore have the potential at least to be sensitive short- term predictors of major earthquakes. The North Anatolian Fault Zone (NAFZ) is a seismicallyactive dextral strike slip fault zone which forms the northern boundary of the westward moving Anatolian plate. It is splayed into three branches at about 31oE and continues westward toward the northern Aegean sea. In this study, we investigate the temporal variation of Dc and the Gutenberg-Richter b-value for seismicity in the western part of the NAFZ (including the northern Aegean sea) for earthquakes of Ms > 4.5 occurring in the period between 1900 and 1992. b ranges from 0.6-1.6 and Dc from 0.6 to 1.4. The b-value is found to be weakly negatively correlated with Dc (r=-0.56). However the (log of) event rate N is positively correlated with b, with a similar degree of statistical significance (r=0.42), and negatively correlated with Dc (r=-0.48). Since N increases dramatically with improved station coverage since 1970, the observed negative correlation between b and Dc is therefore more likely to be due to this effect than any underlying physical process in this case. We present this as an example of how man-made artefacts of recording can have similar statistical effects to underlying processes.
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Deshmukh, Soumen, Rajesh Sharma, Manisha Chaudhary, and Harilal. "Integrated 3D geomechanical modeling and its application for well planning in Bantumilli South area, Krishna-Godavari Basin, India." Leading Edge 39, no. 3 (March 2020): 182–87. http://dx.doi.org/10.1190/tle39030182.1.
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Complex geologic structure, a heterogeneous reservoir, and complications related to high pressure during drilling necessitate carrying out geomechanical modeling to understand the physical properties of rocks and fluids present within the Early Cretaceous synrift sequence in the Bantumilli South area of the Krishna-Godavari Basin in India. Reservoirs within the synrift sequence exhibit low permeability and high pore pressure. Identification of safe mud-weight window zones is critical for safe drilling of wells in this part of the basin. A detailed workflow for building a robust 3D geomechanical model and its applications to well planning and hydraulic fracturing are presented. Elastic properties of the reservoirs were estimated by prestack seismic inversion. Elastic properties and pore pressure volumes were used to simulate the 3D stress field. The maximum horizontal stress direction is observed to be 130°N ± 5°, i.e., northwest to southeast, and estimated fracture pressure (minimum horizontal stress) values range between 10,000 and 14,200 psi within the synrift sequence. The study has shown that the Cretaceous section of the reservoir has narrow mud-weight window zones. These zones are governed mainly by a high pore pressure regime in the reservoirs. Additionally, deep-seated basement faults have played an important role in the compartmentalization of the reservoir in terms of geomechanical properties.
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Chen, Zhengyu, Qirong Qin, Hu Li, Jiling Zhou, and Jie Wang. "Reservoir Characteristics and Main Factors Controlling Carboniferous Volcanic Rocks in the Well CH471 Area of the Hongche Fault Zone: Northwest Margin of Junggar Basin, China." Minerals 13, no. 11 (November 19, 2023): 1455. http://dx.doi.org/10.3390/min13111455.
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Nearly 100 million tons of reserves have been explored in the Well 471 area of the Hongche Fault zone. The Carboniferous volcanic rock reservoir is the main oil-bearing reservoir in the well CH471 area and is the main target of exploration and development. The characteristics of the Carboniferous volcanic rock reservoir are studied through core, thin section, physical property, logging, and other data, and its main controlling factors are analyzed in combination with actual means of production. The lithologies of the volcanic reservoir in the study area are mainly volcanic breccia, andesite, and basalt. The matrix physical properties of volcanic rock reservoirs are medium-porosity and ultralow-permeability, among which volcanic breccia has the best physical properties. The reservoir space mainly comprises primary pores, secondary dissolution pores, and fractures, resulting in a dual medium pore-fracture-type reservoir. Combined with production data analysis, the lateral distribution of oil and gas is controlled by lithology and lithofacies, with explosive volcanic breccia being the best, followed by the basalt and andesite of overflow facies, which are vertically affected by weathering and leaching and distributed within 50~300 m from the top of the Carboniferous system. The area with densely developed fractures was conducive to developing high-quality reservoirs. The tectonic movement promoted the formation of weathering and controlled the development of faults. Based on a comprehensive analysis, it is believed that the formation of Carboniferous volcanic oil and gas reservoirs in the study area was controlled and influenced by the lithology, lithofacies, weathering, leaching, faults (fractures), and tectonics.
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Tosun, H., E. Seyrek, A. Orhan, H. Savaş, and M. Türköz. "Soil liquefaction potential in Eskişehir, NW Turkey." Natural Hazards and Earth System Sciences 11, no. 4 (April 7, 2011): 1071–82. http://dx.doi.org/10.5194/nhess-11-1071-2011.
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Abstract. Liquefaction is one of the critical problems in geotechnical engineering. High ground water levels and alluvial soils have a high potential risk for damage due to liquefaction, especially in seismically active regions. Eskişehir urban area, studied in this article, is situated within the second degree earthquake region on the seismic hazard zonation map of Turkey and is surrounded by Eskişehir, North Anatolian, Kütahya and Simav Fault Zones. Geotechnical investigations are carried out in two stages: field and laboratory. In the first stage, 232 boreholes in different locations were drilled and Standard Penetration Test (SPT) was performed. Test pits at 106 different locations were also excavated to support geotechnical data obtained from field tests. In the second stage, experimental studies were performed to determine the Atterberg limits and physical properties of soils. Liquefaction potential was investigated by a simplified method based on SPT. A scenario earthquake of magnitude M=6.4, produced by Eskişehir Fault Zone, was used in the calculations. Analyses were carried out for PGA levels at 0.19, 0.30 and 0.47 g. The results of the analyses indicate that presence of high ground water level and alluvial soil increase the liquefaction potential with the seismic features of the region. Following the analyses, liquefaction potential maps were produced for different depth intervals and can be used effectively for development plans and risk management practices in Eskişehir.
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Chicco, Jessica, Damiano Vacha, and Giuseppe Mandrone. "Thermo-Physical and Geo-Mechanical Characterization of Faulted Carbonate Rock Masses (Valdieri, Italy)." Remote Sensing 11, no. 2 (January 18, 2019): 179. http://dx.doi.org/10.3390/rs11020179.
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Water in rock masses is a key factor in geo-mechanics, hydrogeology, mining, geo-thermics, and more. It is relevant in interpreting rock mass behavior (e.g., water-rock interaction or slope stability), as well as in defining heat transfer mechanisms. Pointing out the contribution of secondary porosity in increasing advective heat transfer instead of the conduction phenomenon, this study aims to highlight a different thermal response of sound rocks and faulted zones. Moreover, it provides some methodological suggestions to minimize environment disturbance in data collection and a robust interpretation of the results. An interesting outcrop was identified in a carbonate quarry near Valdieri (north-west Italian Alps): it was studied coupling a geo-mechanical and a thermo-physical approach. In particular, geo-mechanical and photogrammetric surveys, InfraRed Thermography (IRT), and Thermal Conductivity (TC) measurements were conducted. The rationale of the research is based on the fact that, when a substantial temperature difference between flowing groundwater and rocks was detected, IRT can reveal information about geo-mechanical and hydrogeological properties of the rock masses such as a degree of fracturing and joint interconnection. A comparative field and laboratory analysis using different devices enabled a more detailed insight providing values in both dry and wet conditions. A different thermal response was highlighted for the cataclastic zone as well. IRT results showed an evident inverse relationship among the number of joints per meter and the detected surface temperature. This is probably caused by the higher water flow within the cataclastic fault zone. Moreover, low fractured portions of the rock mass presented higher cooling rates and conducted heat far more than those with poor geo-mechanical characteristics (difference up to 40%). A negligible ratio between wet and dried thermal conductivity (about 1%) was also detected in lab measurements, which confirmed that primary porosity is not usually relevant in influencing thermal properties of the sound rock.
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Krawczyk, C. M., M. L. Buddensiek, O. Oncken, and N. Kukowski. "Seismic imaging of sandbox experiments – laboratory hardware setup and first reflection seismic sections." Solid Earth 4, no. 1 (February 15, 2013): 93–104. http://dx.doi.org/10.5194/se-4-93-2013.
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Abstract. With the study and technical development introduced here, we combine analogue sandbox simulation techniques with seismic physical modelling of sandbox models. For that purpose, we designed and developed a new mini-seismic facility for laboratory use, comprising a seismic tank, a PC-driven control unit, a positioning system, and piezoelectric transducers used here for the first time in an array mode. To assess the possibilities and limits of seismic imaging of small-scale structures in sandbox models, different geometry setups were tested in the first 2-D experiments that also tested the proper functioning of the device and studied the seismo-elastic properties of the granular media used. Simple two-layer models of different materials and layer thicknesses as well as a more complex model comprising channels and shear zones were tested using different acquisition geometries and signal properties. We suggest using well sorted and well rounded grains with little surface roughness (glass beads). Source receiver-offsets less than 14 cm for imaging structures as small as 2.0–1.5 mm size have proven feasible. This is the best compromise between wide beam and high energy output, and is applicable with a consistent waveform. Resolution of the interfaces of layers of granular materials depends on the interface preparation rather than on the material itself. Flat grading of interfaces and powder coverage yields the clearest interface reflections. Finally, sandbox seismic sections provide images of high quality showing constant thickness layers as well as predefined channel structures and indications of the fault traces from shear zones. Since these were artificially introduced in our test models, they can be regarded as zones of disturbance rather than tectonic shear zones characterized by decompaction. The multiple-offset surveying introduced here, improves the quality with respect to S / N ratio and source signature even more; the maximum depth penetration in glass-bead layers thereby amounts to 5 cm. Thus, the presented mini-seismic device is already able to resolve structures within simple models of saturated porous media, so that multiple-offset seismic imaging of shallow sandbox models, that are structurally evolving, is generally feasible.
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Krawczyk, C. M., M. L. Buddensiek, O. Oncken, and N. Kukowski. "Seismic imaging of sandbox experiments – laboratory hardware setup and first reflection seismic sections." Solid Earth Discussions 4, no. 2 (October 10, 2012): 1317–44. http://dx.doi.org/10.5194/sed-4-1317-2012.
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Abstract. With the study and technical development introduced here, we combine analogue sandbox simulation techniques with seismic physical modelling of sandbox models. For that purpose, we designed and developed a new mini-seismic facility for laboratory use, comprising a seismic tank, a PC-driven control unit, a positioning system, and piezo-electric transducers used here the first time in an array mode. To assess the possibilities and limits of seismic imaging of small-scale structures in sandbox models, different geometry setups were tested in the first experiments that also tested the proper functioning of the device and studied the seismo-elastic properties of the granular media used. Simple two-layer models of different materials and layer thicknesses as well as a more complex model comprising channels and shear zones were tested using different acquisition geometries and signal properties. We suggest using well sorted and well rounded grains with little surface roughness (glass beads). Source receiver-offsets less than 14 cm for imaging structures as small as 2.0–1.5 mm size have proven feasible. This is the best compromise between wide beam and high energy output, and being applicable with a consistent waveform. Resolution of the interfaces of layers of granular materials depends on the interface preparation rather than on the material itself. Flat grading of interfaces and powder coverage yields the clearest interface reflections. Finally, sandbox seismic sections provide images of very good quality showing constant thickness layers as well as predefined channel structures and fault traces from shear zones. Since these can be regarded in sandbox models as zones of decompaction, they behave as reflectors and can be imaged. The multiple-offset surveying introduced here improves the quality with respect to S/N-ratio and source signature even more; the maximum depth penetration in glass bead layers thereby amounts to 5 cm. Thus, the presented mini-seismic device is already able to resolve structures within simple models of saturated porous media, so that multiple-offset seismic imaging of shallow sandbox models, that are structurally evolving, is generally feasible.
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Kadirov, Vokhid, Sherzod Karimov, Uchqun Qushshayev, and Durdona Sharapova. "Study on the influence of the deformation zones of the quarry sides on the rock mass movement." E3S Web of Conferences 304 (2021): 02002. http://dx.doi.org/10.1051/e3sconf/202130402002.
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The article presents a study and analysis of the causes of deformation of the slopes and sides of the quarry indicates that the magnitude and nature of the deformation processes depend on the height of the ledge, the angle of slope of the slopes, the physical and mechanical properties, the lithological and structural features of the instrument array and the geodynamic activity of the fault zones. The influence of the deformation zones of the sides of the quarry on the transport of rock masses is justified. The zone of deformed masses of the ore deposit, which affect the movement of the rock mass, is studied. Each process performed in open pit mining is linked to another workflow. Without ensuring the safety of mining operations and performing the tasks set is impossible. Transportation of rock masses in the lower horizons of a deep quarry is one of the main tasks of the industry. At the same time, the removal of deformation and landslides in the area where the transport berm is being constructed for draining and continuous transportation is the main goal of the quarry. The stability of the transport berm depends directly on the stability of the side of the quarry. It is determined that the choice of a single-lane or twolane transport berm constructed for heavy-duty quarry dump trucks depends on the condition of the side of the quarry.
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Salinas-Martínez, Alfredo, Ana María Aguilar-Molina, Jennifer Pérez-Oregon, Fernando Angulo-Brown, and Alejandro Muñoz-Diosdado. "Review and Update on Some Connections between a Spring-Block SOC Model and Actual Seismicity in the Case of Subduction Zones." Entropy 24, no. 4 (March 22, 2022): 435. http://dx.doi.org/10.3390/e24040435.
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The self-organized critical (SOC) spring-block models are accessible and powerful computational tools for the study of seismic subduction. This work aims to highlight some important findings through an integrative approach of several actual seismic properties, reproduced by using the Olami, Feder, and Christensen (OFC) SOC model and some variations of it. A few interesting updates are also included. These results encompass some properties of the power laws present in the model, such as the Gutenberg-Richter (GR) law, the correlation between the parameters a and b of the linear frequency-magnitude relationship, the stepped plots for cumulative seismicity, and the distribution of the recurrence times of large earthquakes. The spring-block model has been related to other relevant properties of seismic phenomena, such as the fractal distribution of fault sizes, and can be combined with the work of Aki, who established an interesting relationship between the fractal dimension and the b-value of the Gutenberg-Richter relationship. Also included is the work incorporating the idea of asperities, which allowed us to incorporate several inhomogeneous models in the spring-block automaton. Finally, the incorporation of a Ruff-Kanamori-type diagram for synthetic seismicity, which is in reasonable accordance with the original Ruff and Kanamori diagram for real seismicity, is discussed.
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LOBANOV, Konstantin V., Mikhail V. CHICHEROV, and Nikolay V. SHAROV. "The 50th Anniversary of the Start of Drilling the Kola Superdeep Well." Arctic and North, no. 44 (September 24, 2021): 267–84. http://dx.doi.org/10.37482/issn2221-2698.2021.44.267.
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The Kola Superdeep Well (SG-3) is an outstanding achievement of Soviet science and technology, drilled in Precambrian crystalline rocks and reached a depth of 12262 m. It was one of a series of super deep wells planned within the framework of the program “Earth's Interior Exploration and Superdeep Drilling”. In order to achieve record depths, unique domestic drilling equipment and materials capable of working at high temperatures and pressures were created. A fundamentally new technology for drilling wells using hydraulic downhole motors was developed. Despite difficult drilling conditions and repeated acci-dents, SG-3 has fulfilled almost all the tasks assigned to it. The well was penetrated with full core sampling, which was subjected to comprehensive study. This made it possible to study the deep structure of the Earth's crust and to revise the interpretation of depth seismic data. It was found that changes in the physical properties of rocks at great depths had been erroneously interpreted as a change in their composition. It made it possible to assess the prospects of deep horizons of the Pechenga structure for copper-nickel mineralisation by uncovering a previously unknown body of ore-bearing hyperbasites. New information was obtained on the temperature gradient, which turned out to be significantly higher than expected, as well as on the vertical metamorphic zoning along the borehole section. The composition and physical properties of rocks in deep horizons were investigated. Tectonic fault zones and six types of ore mineralisation were identified in the borehole section. New data on ore formation processes at great depths have been obtained, which is an important contribution to the theory of mineral deposit formation
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Zhao, Ranlei, Xiao Xu, Wentao Ma, Cunlei Li, Qiushi Zhang, and Qingyou Yue. "Reservoir Characteristics and Controlling Factors of Sedimentary Pyroclastic Rocks in Deep-Buried Basins: A Case Study of Yingtai Fault Depression, Southern Songliao Basin." Energies 15, no. 18 (September 9, 2022): 6594. http://dx.doi.org/10.3390/en15186594.
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In this article, based on core description, thin section, scanning electron microscope (SEM), well logging and reservoir physical properties, the reservoir controlling factors of sedimentary pyroclastic rocks in deep-buried basins are assessed via the relation between reservoirs and defining factors, including lithological characteristics, sedimentary microfacies and diagenesis. In addition, the contributing factors of anomalously high-porosity and high-permeability zone are analyzed. The lithological characteristics and diagenesis of the sedimentary pyroclastic rocks are closely related to reservoirs. The reservoir porosity–permeability of sedimentary pyroclastic rocks with large volcanic clastic particles is better than in those with small volcanic clastic particles. Sedimentary pyroclastic rocks with high content of unstable clastic particles, such as feldspar and rock debris, are easier to form the high-quality reservoirs than those with high content of quartz. The dissolution is the most important and direct reason to form the anomalously high-porosity and high-permeability zones of the sedimentary pyroclastic rocks in deep-buried basins. It is concluded that the size and composition of the clastic particles in the sedimentary pyroclastic rocks are the internal-controlling factors of the effective reservoirs, while the diagenetic fluid and the burial process are the external-controlling factors which form the effective reservoirs.
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Carrillo, Jonathan, Marco A. Perez-Flores, Luis A. Gallardo, and Eva Schill. "Joint inversion of gravity and magnetic data using correspondence maps with application to geothermal fields." Geophysical Journal International 228, no. 3 (October 9, 2021): 1621–36. http://dx.doi.org/10.1093/gji/ggab416.
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SUMMARY Current geophysical joint inversion methods can be roughly divided into structurally or property driven. While structural coupling plays a key role in fully heterogeneous environments, it is blind to the actual physical properties, which limit its application. On the other hand, approaches based on direct property-correlations promise strong coupled models using petrophysical linkages derived from rock physics or through the search for cross-property relationships in the objective function directly, for example, fuzzy-clusters or correspondence maps. We apply a correspondence maps (CM) methodology to the joint estimation of density and magnetization in 3-D environments using gravity and magnetic data. CM joint inversion has yet to be applied to the specific combination of gravity and magnetic data, nor compared to other approaches like cross-gradient coupling or fuzzy-clustering. The CM searches for cross-property functional relationships; it has the potential to allow a gradual property variation that is not restricted to a predetermined number of homogeneous zones. We tested the algorithm using two illustrative synthetic examples to analyse the compositional and geometrical improvements and thoroughly investigate its capacity to recover a study model based on potential features in a geothermal scenario using polynomials. We investigated the case of using lower and higher polynomials than required for recovering the second synthetic model. The nature of the inversion suggested instability when high-grade polynomials were used, which was successfully overcome by gradually increasing the number of coefficients. The strategy was satisfactorily implemented to the field data. We applied the algorithm over the Los Humeros geothermal field in Mexico and fit a quadratic relationship between density and magnetization that exhibits two main zones consistent with previous works. The first one contains relatively low density and high magnetization. The second zone contains low density and low magnetization values. In this last zone, we emphasize that an observed link between low density, low magnetization, and major fault zones with high relevance to geothermal exploration is resulting from joint inversion, only. We achieved an enhanced petrophysical and structural integrated subsurface imaging in synthetic and field cases at the expense of slightly increased RMS misfit value.
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Pilecki, Zenon. "Geophysical identification of voids and loosened zones in the shallow subsurface of post-mining areas." E3S Web of Conferences 66 (2018): 01001. http://dx.doi.org/10.1051/e3sconf/20186601001.
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The shallow historic exploitation of Zn-Pb/Fe ore deposits as well as hard coal has generated many discontinuous deformations on the terrain surface in the Upper Silesian Coal Basin/Poland. Discontinuous deformations occur in different forms as sinkholes, synclines, cracks, faults or ditches. The basic cause of their occurrence is the presence of void and loosened zones in the shallow subsurface. If the appropriate conditions arise, the sinkhole process begins to move upwards and may cause a discontinuous deformation on the terrain surface. Typically, geophysical methods are used for void and loosened zone identification. The most effective methods are gravimetric, seismic, electric resistivity and ground penetrating radar (GPR). Geophysical testing, requires distinct changes in the physical properties in the rock mass. The identified geophysical anomalies should be verified by control borehole and borehole tests to confirm the presence of the void and loosened zones in the rock mass. The results of control drilling and borehole tests determine the need to apply treatment works. In order to assess the threat of the occurrence of discontinuous deformations in the areas of historical shallow mining in Upper Silesia, a classification system based on geophysical tests has also been developed.
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Taylor, George, Sebastian Rost, Gregory A. Houseman, and Gregor Hillers. "Near-surface structure of the North Anatolian Fault zone from Rayleigh and Love wave tomography using ambient seismic noise." Solid Earth 10, no. 2 (March 6, 2019): 363–78. http://dx.doi.org/10.5194/se-10-363-2019.
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Abstract. We use observations of surface waves in the ambient noise field recorded at a dense seismic array to image the North Anatolian Fault zone (NAFZ) in the region of the 1999 magnitude 7.6 Izmit earthquake in western Turkey. The NAFZ is a major strike-slip fault system extending ∼1200 km across northern Turkey that poses a high level of seismic hazard, particularly to the city of Istanbul. We obtain maps of phase velocity variation using surface wave tomography applied to Rayleigh and Love waves and construct high-resolution images of S-wave velocity in the upper 10 km of a 70 × 30 km region around Lake Sapanca. We observe low S-wave velocities (<2.5 km s−1) associated with the Adapazari and Pamukova sedimentary basins, as well as the northern branch of the NAFZ. In the Armutlu Block, between the two major branches of the NAFZ, we image higher velocities (>3.2 km s−1) associated with a shallow crystalline basement. We measure azimuthal anisotropy in our phase velocity observations, with the fast direction seeming to align with the strike of the fault at periods shorter than 4 s. At longer periods up to 10 s, the fast direction aligns with the direction of maximum extension for the region (∼45∘). The signatures of both the northern and southern branches of the NAFZ are clearly associated with strong gradients in seismic velocity that also denote the boundaries of major tectonic units. Our results support the conclusion that the development of the NAFZ has exploited this pre-existing contrast in physical properties.