Site response analyses at large strains are routinely carried out neglecting the shear strength of soil and the stiffness degradation due to the increase in pore pressures, leading to unrealistic predictions of the seismic response of soil deposits. The study investigates the performance of a simplified nonlinear (NL) approach, implemented in the Deepsoil code, constituted by coupling a hyperbolic model incorporating shear strength with a strain-based semi-empirical pore pressure generation model. The first part of the study, based on a large one-dimensional parametric study, shows that above a shear strain of 0.1%, it is necessary to include shear strength in the site response modelling to get more realistic results. Then, the approach has been evaluated with reference to the well-known downhole Large-Scale Seismic Test array located in Lotung (Taiwan): numerical results have been compared with recordings in terms of acceleration response spectra and pore water pressure time histories at different depths along the soil profiles. The comparison shows that the NL simplified model is characterized by an accuracy comparable with more sophisticated advanced elasto-plastic NL analyses adopting essentially the same input data of the traditional equivalent linear approaches(shear modulus and damping curves) and simple physical-mechanical properties routinely determined during geotechnical surveys (i.e., shear strength, relative density, fine content). This approach is therefore recommended for site response analyses reaching large strains (i.e., soft soil deposits and moderate-to-high input motions).
{"title":"Numerical modeling of site response at large strains with simplified nonlinear models: Application to Lotung seismic array","authors":"Francesco Di Buccio, Alessandro Pagliaroli","doi":"10.1515/geo-2022-0627","DOIUrl":"https://doi.org/10.1515/geo-2022-0627","url":null,"abstract":"Site response analyses at large strains are routinely carried out neglecting the shear strength of soil and the stiffness degradation due to the increase in pore pressures, leading to unrealistic predictions of the seismic response of soil deposits. The study investigates the performance of a simplified nonlinear (NL) approach, implemented in the Deepsoil code, constituted by coupling a hyperbolic model incorporating shear strength with a strain-based semi-empirical pore pressure generation model. The first part of the study, based on a large one-dimensional parametric study, shows that above a shear strain of 0.1%, it is necessary to include shear strength in the site response modelling to get more realistic results. Then, the approach has been evaluated with reference to the well-known downhole Large-Scale Seismic Test array located in Lotung (Taiwan): numerical results have been compared with recordings in terms of acceleration response spectra and pore water pressure time histories at different depths along the soil profiles. The comparison shows that the NL simplified model is characterized by an accuracy comparable with more sophisticated advanced elasto-plastic NL analyses adopting essentially the same input data of the traditional equivalent linear approaches(shear modulus and damping curves) and simple physical-mechanical properties routinely determined during geotechnical surveys (i.e., shear strength, relative density, fine content). This approach is therefore recommended for site response analyses reaching large strains (i.e., soft soil deposits and moderate-to-high input motions).","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"28 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study determines the mineralogical, petrographical, and geochemical properties of the rocks outcropping in geothermal areas west of the Cappadocia geothermal region. These areas include Ziga, Narlıgöl, Belisırma, Ilısu, and Sivrihisar. The study reveals their hydrothermal alteration characteristics. Also, the study aims to determine the zones of hydrothermal alterations using remote sensing. Rock samples from geothermal areas were performed using optical microscopy, X-ray diffraction (XRD), scanning electron microscopy, X-ray fluorescence spectroscopy, and inductively coupled plasma–mass spectrometry techniques for the determination of mineralogical assemblages and major, trace and REE's analyses. Rock samples, determined as ignimbrites and tuff, exhibit intensive alterations. XRD analysis determined the association of alteration minerals. The dominant clay minerals were kaolinite, montmorillonite, and illite. The analyses and mineral associations are compatible with argillic, mid-argillic alteration, and silicification zones. Alteration zones were identified by classifying the ASTER satellite images of kaolinite, illite, and montmorillonite using the CROSTA technique. The alteration zones observed in this study are close to existing geothermal areas. In addition, different regions with these alterations have been identified within the study area and are expected to be a valuable reference for future geothermal exploration.
{"title":"Evaluation of alteration in the geothermal province west of Cappadocia, Türkiye: Mineralogical, petrographical, geochemical, and remote sensing data","authors":"Hacer Bilgilioglu","doi":"10.1515/geo-2022-0675","DOIUrl":"https://doi.org/10.1515/geo-2022-0675","url":null,"abstract":"This study determines the mineralogical, petrographical, and geochemical properties of the rocks outcropping in geothermal areas west of the Cappadocia geothermal region. These areas include Ziga, Narlıgöl, Belisırma, Ilısu, and Sivrihisar. The study reveals their hydrothermal alteration characteristics. Also, the study aims to determine the zones of hydrothermal alterations using remote sensing. Rock samples from geothermal areas were performed using optical microscopy, X-ray diffraction (XRD), scanning electron microscopy, X-ray fluorescence spectroscopy, and inductively coupled plasma–mass spectrometry techniques for the determination of mineralogical assemblages and major, trace and REE's analyses. Rock samples, determined as ignimbrites and tuff, exhibit intensive alterations. XRD analysis determined the association of alteration minerals. The dominant clay minerals were kaolinite, montmorillonite, and illite. The analyses and mineral associations are compatible with argillic, mid-argillic alteration, and silicification zones. Alteration zones were identified by classifying the ASTER satellite images of kaolinite, illite, and montmorillonite using the CROSTA technique. The alteration zones observed in this study are close to existing geothermal areas. In addition, different regions with these alterations have been identified within the study area and are expected to be a valuable reference for future geothermal exploration.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"2 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qing Guo, Huiming An, Li Zhao, Leilei Zhang, Liang Tao
Fine characterization of oil plane distribution in highly heterogeneous tight sandstone is a prerequisite for efficient reservoir development. This study systematically evaluated the distribution characteristics of tight oil in the Chang 7 Member of the Western Ordos Basin using a large number of experimental tests, logging interpretation, and 3D modelling methods. The logging interpretation models of shale content, porosity, permeability, and oil saturation were constructed, and the effective reservoir was identified by establishing the intersection identification pattern of reservoir acoustic wave time difference and deep lateral resistivity. The 3D numerical simulation results showed that the tight oil is distributed between injection and production wells. The areas with high tight oil content are mainly distributed along the WE direction, and a series of high remaining oil zones are formed locally. Under the influence of long-term injection and production, a high permeability zone will be formed between wells, which is similar to a high-speed channel and will be flooded quickly, and a banded remaining oil retention zone will be formed around it. For the horizontal well flooding area, the water flooding range of the water injection well is small, and a large amount of remaining oil is enriched between water injection wells. Finally, the classification standard of the remaining oil in the Chang 72 sub-member of the study area is proposed, and then, the strategy of adopting different development and adjustment schemes according to different types of reservoirs is formed.
精细描述高度异质致密砂岩中的油面分布是高效开发储层的前提。本研究采用大量的实验测试、测井解释和三维建模方法，系统评价了鄂尔多斯盆地西部长7系致密油的分布特征。构建了页岩含量、孔隙度、渗透率、含油饱和度等测井解释模型，并通过建立储层声波时差与深部侧向电阻率的交汇识别模式，确定了有效储层。三维数值模拟结果表明，致密油分布在注入井和生产井之间。致密油含量高的区域主要沿 WE 方向分布，局部形成一系列高剩余油区。在长期注采的影响下，井间会形成一个类似高速通道的高渗透区，并迅速被水淹，周围会形成带状剩余油滞留区。对于水平井水淹区，注水井水淹范围小，注水井间富集大量剩余油。最后，提出了研究区长 72 子单元剩余油的划分标准，进而形成了针对不同类型油藏采取不同开发调整方案的策略。
{"title":"Distribution law of Chang 7 Member tight oil in the western Ordos Basin based on geological, logging and numerical simulation techniques","authors":"Qing Guo, Huiming An, Li Zhao, Leilei Zhang, Liang Tao","doi":"10.1515/geo-2022-0602","DOIUrl":"https://doi.org/10.1515/geo-2022-0602","url":null,"abstract":"Fine characterization of oil plane distribution in highly heterogeneous tight sandstone is a prerequisite for efficient reservoir development. This study systematically evaluated the distribution characteristics of tight oil in the Chang 7 Member of the Western Ordos Basin using a large number of experimental tests, logging interpretation, and 3D modelling methods. The logging interpretation models of shale content, porosity, permeability, and oil saturation were constructed, and the effective reservoir was identified by establishing the intersection identification pattern of reservoir acoustic wave time difference and deep lateral resistivity. The 3D numerical simulation results showed that the tight oil is distributed between injection and production wells. The areas with high tight oil content are mainly distributed along the WE direction, and a series of high remaining oil zones are formed locally. Under the influence of long-term injection and production, a high permeability zone will be formed between wells, which is similar to a high-speed channel and will be flooded quickly, and a banded remaining oil retention zone will be formed around it. For the horizontal well flooding area, the water flooding range of the water injection well is small, and a large amount of remaining oil is enriched between water injection wells. Finally, the classification standard of the remaining oil in the Chang 7<jats:sub>2</jats:sub> sub-member of the study area is proposed, and then, the strategy of adopting different development and adjustment schemes according to different types of reservoirs is formed.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"33 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to reveal the restriction in shale gas enrichment of the Wufeng-Longmaxi Formation in the northern Guizhou province, the influence model of detachment layer was established through field geological investigation, core observation, logging, sample analysis, and geological background data. The response relationship between the detachment layer and the shale gas enrichment model in different structural formats was analyzed. The results show that the thickness of the Wufeng-Longmaxi Formation’s detachment layer is influenced by the conditions near the fault zones and mineralogical characteristics. The lithofacies of the detachment layer shows mainly a combination of clay-rich shale facies. This indicates that lithofacies type is one of the main factors influencing the variation in slip layer thickness. The detachment layer exhibits distinct well logging response characteristics and is influenced by nitrogen enrichment. The development of detachment fractures allows atmospheric nitrogen to infiltrate shale gas. It leads to poor gas saturation in the shale gas. In addition, the overall tectonic deformation in the northern Guizhou province was found to gradually intensify from Northwest to Southeast, and there were two tectonic models: a slot-shift tape transition belt and a spacer type deformation belt. The influence of decollements on shale gas preservation was barely found in the northern Guizhou province. It is mainly controlled by buried depth of the target layer, conditions of the cover layer, structural type, and deformation intensity.
{"title":"Structural detachment influences the shale gas preservation in the Wufeng-Longmaxi Formation, Northern Guizhou Province","authors":"Sheng Shi, Ganlu Wang, Yuliang Mou, Xiangfeng Wei","doi":"10.1515/geo-2022-0653","DOIUrl":"https://doi.org/10.1515/geo-2022-0653","url":null,"abstract":"In order to reveal the restriction in shale gas enrichment of the Wufeng-Longmaxi Formation in the northern Guizhou province, the influence model of detachment layer was established through field geological investigation, core observation, logging, sample analysis, and geological background data. The response relationship between the detachment layer and the shale gas enrichment model in different structural formats was analyzed. The results show that the thickness of the Wufeng-Longmaxi Formation’s detachment layer is influenced by the conditions near the fault zones and mineralogical characteristics. The lithofacies of the detachment layer shows mainly a combination of clay-rich shale facies. This indicates that lithofacies type is one of the main factors influencing the variation in slip layer thickness. The detachment layer exhibits distinct well logging response characteristics and is influenced by nitrogen enrichment. The development of detachment fractures allows atmospheric nitrogen to infiltrate shale gas. It leads to poor gas saturation in the shale gas. In addition, the overall tectonic deformation in the northern Guizhou province was found to gradually intensify from Northwest to Southeast, and there were two tectonic models: a slot-shift tape transition belt and a spacer type deformation belt. The influence of decollements on shale gas preservation was barely found in the northern Guizhou province. It is mainly controlled by buried depth of the target layer, conditions of the cover layer, structural type, and deformation intensity.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"67 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vojislav Deđanski, Uroš Durlević, Aleksandar Kovjanić, Tin Lukić
Landslides and slope processes constitute one of the most frequent natural hazards in valleys near major rivers and mountainous regions. The surface layer, characterized by its relatively loose composition, is prone to sliding due to a combination of distinct natural and human-related factors. Specific sections along the right bank of the Danube River in Smederevo city exhibit significant susceptibility to landslide activation, often leading to substantial material losses and posing a risk to the local population. The initial step in the provided research involves analyzing existing literature and mapping landslides within the study area. The initial analysis covers both natural conditions and anthropogenic activities. The second step includes establishing a geospatial database in the Geographic Information System and generating eight thematic maps. In the third step, different weight coefficients were assigned to the criteria, which facilitated the creation of the Landslide Susceptibility Index using the Best–Worst Method. Subsequently, in the fourth step, a composite map illustrating landslide susceptibility was produced. According to this research, about 4% of the territory of Smederevo, or 19.3 km2, is highly or very highly susceptible to landslides. These localities are located on the right bank of the Danube River and around the Ralja River. Receiver operating characteristic-area under the curve value indicates very high predictive power (approximately 1), thus suggesting the reliability of the used methodology. This visualization of areas highly prone to such occurrences empowers policymakers to implement more effective environmental protection measures and institute sustainable management practices for agricultural parcels in this region. Also, the provided research represents the inaugural integration of advanced remote sensing techniques and interdisciplinary investigations, offering deeper insights into landslide activity in the study area and yielding more comprehensive results.
{"title":"GIS-based spatial modeling of landslide susceptibility using BWM-LSI: A case study – city of Smederevo (Serbia)","authors":"Vojislav Deđanski, Uroš Durlević, Aleksandar Kovjanić, Tin Lukić","doi":"10.1515/geo-2022-0688","DOIUrl":"https://doi.org/10.1515/geo-2022-0688","url":null,"abstract":"Landslides and slope processes constitute one of the most frequent natural hazards in valleys near major rivers and mountainous regions. The surface layer, characterized by its relatively loose composition, is prone to sliding due to a combination of distinct natural and human-related factors. Specific sections along the right bank of the Danube River in Smederevo city exhibit significant susceptibility to landslide activation, often leading to substantial material losses and posing a risk to the local population. The initial step in the provided research involves analyzing existing literature and mapping landslides within the study area. The initial analysis covers both natural conditions and anthropogenic activities. The second step includes establishing a geospatial database in the Geographic Information System and generating eight thematic maps. In the third step, different weight coefficients were assigned to the criteria, which facilitated the creation of the Landslide Susceptibility Index using the Best–Worst Method. Subsequently, in the fourth step, a composite map illustrating landslide susceptibility was produced. According to this research, about 4% of the territory of Smederevo, or 19.3 km<jats:sup>2</jats:sup>, is highly or very highly susceptible to landslides. These localities are located on the right bank of the Danube River and around the Ralja River. Receiver operating characteristic-area under the curve value indicates very high predictive power (approximately 1), thus suggesting the reliability of the used methodology. This visualization of areas highly prone to such occurrences empowers policymakers to implement more effective environmental protection measures and institute sustainable management practices for agricultural parcels in this region. Also, the provided research represents the inaugural integration of advanced remote sensing techniques and interdisciplinary investigations, offering deeper insights into landslide activity in the study area and yielding more comprehensive results.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"171 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the southwestern Sichuan Basin, the Jurassic Shaximiao Formation encompasses a multitude of working areas, displaying intricate sedimentary traits. Traditional methods of stratigraphic division based on sequence suffer from inherent subjectivity and limitations. This study employs a combined mathematical approach to use the wavelet transform (WT) and the Hilbert–Huang transform (HHT). It decomposes the natural gamma ray (GR) logging curve into energy spectrum plots and wavelet coefficients at different scales, high and low frequency signals at different frequencies, and a set of intrinsic mode function components and residual functions. The study conducted a detailed stratigraphic division of the Jurassic Shaximiao Formation in the southwestern Sichuan Basin using these methods. The WT offers greater resolution for the periodic changes in the base level, whereas the HHT demonstrates a superior correlation with the positions of stratigraphic interfaces. The combined utilization of the continuous wavelet transform, the discrete wavelet transform, and HHT methods has demonstrated encouraging outcomes in the stratigraphic division of the Jurassic Shaximiao Formation. These methods have been shown to enhance the accuracy of stratigraphic division and to reduce the influence of subjective factors. This study presents new insights and approaches for geological data processing, offering significant theoretical and practical implications and novel technical means for oil and gas exploration and development.
{"title":"Application of the wavelet transform and Hilbert–Huang transform in stratigraphic sequence division of Jurassic Shaximiao Formation in Southwest Sichuan Basin","authors":"Zheng Li, Jingchun Tian, Laixing Cai, Tian Yang","doi":"10.1515/geo-2022-0657","DOIUrl":"https://doi.org/10.1515/geo-2022-0657","url":null,"abstract":"In the southwestern Sichuan Basin, the Jurassic Shaximiao Formation encompasses a multitude of working areas, displaying intricate sedimentary traits. Traditional methods of stratigraphic division based on sequence suffer from inherent subjectivity and limitations. This study employs a combined mathematical approach to use the wavelet transform (WT) and the Hilbert–Huang transform (HHT). It decomposes the natural gamma ray (GR) logging curve into energy spectrum plots and wavelet coefficients at different scales, high and low frequency signals at different frequencies, and a set of intrinsic mode function components and residual functions. The study conducted a detailed stratigraphic division of the Jurassic Shaximiao Formation in the southwestern Sichuan Basin using these methods. The WT offers greater resolution for the periodic changes in the base level, whereas the HHT demonstrates a superior correlation with the positions of stratigraphic interfaces. The combined utilization of the continuous wavelet transform, the discrete wavelet transform, and HHT methods has demonstrated encouraging outcomes in the stratigraphic division of the Jurassic Shaximiao Formation. These methods have been shown to enhance the accuracy of stratigraphic division and to reduce the influence of subjective factors. This study presents new insights and approaches for geological data processing, offering significant theoretical and practical implications and novel technical means for oil and gas exploration and development.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"57 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Filip Vujović, Aleksandar Valjarević, Josep Vila-Subirós, Ante Šiljeg, Tin Lukić
Wildfires pose a significant ecological, environmental, and socioeconomic challenge in southeastern Europe. The preservation of wildlands is not only essential but also a foremost priority for Montenegro, a country recognized as the world’s first ecological state. Consequently, the development of optimal methodologies and models is of paramount importance to enhance fire protection measures. With this objective in mind, this study strives to create a wildfire susceptibility model on a national scale for Montenegro. The study employed seven natural and anthropogenic causative criteria: vegetation type; aspect; slope; elevation; climate classification; distance from road; and population. The modeling process integrates both natural and anthropogenic causal criteria, employing the Fuzzy Analytic Hierarchy Process (F-AHP) and Frequency Ratio (FR) within geoinformatics environment. The outcomes of the F-AHP model reveal that 72.84% of the total area is categorized as having high to very high susceptibility. Conversely, based on the FR model, only 29.07% of the area falls within these susceptibility levels. In terms of validation, the area under curvature values indicates good performance of the F-AHP model. In contrast, the FR model demonstrates poor performance. These novel findings, pertaining to Montenegro at a national scale, offer valuable insights for preemptive wildfire safeguarding efforts. Moreover, the methodologies employed, with necessary modifications, hold potential for application in geographically diverse regions.
{"title":"Geospatial modeling of wildfire susceptibility on a national scale in Montenegro: A comparative evaluation of F-AHP and FR methodologies","authors":"Filip Vujović, Aleksandar Valjarević, Josep Vila-Subirós, Ante Šiljeg, Tin Lukić","doi":"10.1515/geo-2022-0694","DOIUrl":"https://doi.org/10.1515/geo-2022-0694","url":null,"abstract":"Wildfires pose a significant ecological, environmental, and socioeconomic challenge in southeastern Europe. The preservation of wildlands is not only essential but also a foremost priority for Montenegro, a country recognized as the world’s first ecological state. Consequently, the development of optimal methodologies and models is of paramount importance to enhance fire protection measures. With this objective in mind, this study strives to create a wildfire susceptibility model on a national scale for Montenegro. The study employed seven natural and anthropogenic causative criteria: vegetation type; aspect; slope; elevation; climate classification; distance from road; and population. The modeling process integrates both natural and anthropogenic causal criteria, employing the Fuzzy Analytic Hierarchy Process (F-AHP) and Frequency Ratio (FR) within geoinformatics environment. The outcomes of the F-AHP model reveal that 72.84% of the total area is categorized as having high to very high susceptibility. Conversely, based on the FR model, only 29.07% of the area falls within these susceptibility levels. In terms of validation, the area under curvature values indicates good performance of the F-AHP model. In contrast, the FR model demonstrates poor performance. These novel findings, pertaining to Montenegro at a national scale, offer valuable insights for preemptive wildfire safeguarding efforts. Moreover, the methodologies employed, with necessary modifications, hold potential for application in geographically diverse regions.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"8 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Milica Živanović, Miško M. Milanović, Branislav Trivić, Snežana Đurđić, Miroljub Milinčić, Milisav Tomić, Goran Grozdanić
Ensuring the quality protection of geospatial elements entails environmental control, a task unattainable without precise measurement results. This article aims to conduct a spatio-temporal analysis of soil degradation and vegetation status within the influence zone of the Kolubara Mining Basin in Serbia. Remote sensing is employed to assess vulnerability to erosion using the erosion potential method. A geographic information system environment is utilized to generate an erosion map, illustrating erosive processes across different time periods, particularly comparing the present situation (2022) to 1983. Results indicate that observed areas are experiencing erosion due to changes in land use. Furthermore, this study investigates the use of the normalized difference vegetation index to monitor vegetation cover changes from 1992 to 2022. The objective is to demonstrate that these methods effectively depict degradation levels and vegetation status in the area. This comprehensive overview provides insights into the changes occurring across the analyzed years. Such insights are crucial for informing future efforts to restore the region to its natural state prior to lignite mining.
{"title":"Analysis of the intensity of erosive processes and state of vegetation cover in the zone of influence of the Kolubara Mining Basin","authors":"Milica Živanović, Miško M. Milanović, Branislav Trivić, Snežana Đurđić, Miroljub Milinčić, Milisav Tomić, Goran Grozdanić","doi":"10.1515/geo-2022-0682","DOIUrl":"https://doi.org/10.1515/geo-2022-0682","url":null,"abstract":"Ensuring the quality protection of geospatial elements entails environmental control, a task unattainable without precise measurement results. This article aims to conduct a spatio-temporal analysis of soil degradation and vegetation status within the influence zone of the Kolubara Mining Basin in Serbia. Remote sensing is employed to assess vulnerability to erosion using the erosion potential method. A geographic information system environment is utilized to generate an erosion map, illustrating erosive processes across different time periods, particularly comparing the present situation (2022) to 1983. Results indicate that observed areas are experiencing erosion due to changes in land use. Furthermore, this study investigates the use of the normalized difference vegetation index to monitor vegetation cover changes from 1992 to 2022. The objective is to demonstrate that these methods effectively depict degradation levels and vegetation status in the area. This comprehensive overview provides insights into the changes occurring across the analyzed years. Such insights are crucial for informing future efforts to restore the region to its natural state prior to lignite mining.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"18 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The study of tectonic activity holds great significance in assessing historical and modern seismic risks. The Weihe Graben is a significant intracontinental graben system in China, with numerous active faults that have caused a series of earthquakes, including the Huaxian great earthquake (M ∼ 8.5) in 1556 with approximately 830,000 deaths. Despite the obvious spatial relationship between the Weihe fault (WF) and these earthquakes, detailed research on the fault is still lacking. Various techniques including remote sensing images, digital elevation model, shallow seismic lines, trench excavation, drilling sections, and optically stimulated luminescence dating, have been utilized to obtain the following results: (1) The WF passes through the scarp of the Weihe River terrace in the north of Xianyang and can be divided into east and west sections at Jinjia village; (2) The WF is a normal fault that strikes northeast and dips south with a dipping angle of 65°–75°; (3) The fault has been active during the Holocene; (4) The vertically offset and dating results suggest that the fault activity has gradually decreased since the late Pleistocene, and the vertical slip rate during the Holocene is only 0.04–0.13 mm/year.
{"title":"Structural features and tectonic activity of the Weihe Fault, central China","authors":"Qinhu Tian, Shidi Wang, Xiaoni Li, Lei Liu","doi":"10.1515/geo-2022-0674","DOIUrl":"https://doi.org/10.1515/geo-2022-0674","url":null,"abstract":"The study of tectonic activity holds great significance in assessing historical and modern seismic risks. The Weihe Graben is a significant intracontinental graben system in China, with numerous active faults that have caused a series of earthquakes, including the Huaxian great earthquake (<jats:italic>M</jats:italic> ∼ 8.5) in 1556 with approximately 830,000 deaths. Despite the obvious spatial relationship between the Weihe fault (WF) and these earthquakes, detailed research on the fault is still lacking. Various techniques including remote sensing images, digital elevation model, shallow seismic lines, trench excavation, drilling sections, and optically stimulated luminescence dating, have been utilized to obtain the following results: (1) The WF passes through the scarp of the Weihe River terrace in the north of Xianyang and can be divided into east and west sections at Jinjia village; (2) The WF is a normal fault that strikes northeast and dips south with a dipping angle of 65°–75°; (3) The fault has been active during the Holocene; (4) The vertically offset and dating results suggest that the fault activity has gradually decreased since the late Pleistocene, and the vertical slip rate during the Holocene is only 0.04–0.13 mm/year.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"26 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shaojun Dai, Jian Zhou, Xianping Ning, Jianxin Xu, Hua Wang
An accurate survey of field vegetation information facilitates the evaluation of ecosystems and the improvement of remote sensing models. Extracting fractional vegetation cover (FVC) information using aerial images is one of the important areas of unmanned aerial vehicles. However, for a field with diverse vegetation species and a complex surface environment, FVC estimation still has difficulty guaranteeing accuracy. A segmented FVC calculation method based on a thresholding algorithm is proposed to improve the accuracy and speed of FVC estimation. The FVC estimation models were analyzed by randomly selected sample images using four vegetation indices: excess green, excess green minus excess red index, green leaf index, and red green blue vegetation index (RGBVI). The results showed that the empirical model method performed poorly (validating R2 = 0.655 to 0.768). The isodata and triangle thresholding algorithms were introduced for vegetation segmentation, and their accuracy was analyzed. The results showed that the correlation between FVC estimation under RGBVI was the highest, and the triangle and isodata thresholding algorithms were complementary in terms of vegetation recognition accuracy, based on which a segmentation method of FVC calculation combining triangle and isodata algorithms was proposed. After testing, the accuracy of the improved FVC calculation method is higher than 90%, and the vegetation recognition accuracy is improved to more than 80%. This study is a positive guide to using digital cameras in field surveys.
{"title":"Estimation model of wild fractional vegetation cover based on RGB vegetation index and its application","authors":"Shaojun Dai, Jian Zhou, Xianping Ning, Jianxin Xu, Hua Wang","doi":"10.1515/geo-2022-0661","DOIUrl":"https://doi.org/10.1515/geo-2022-0661","url":null,"abstract":"An accurate survey of field vegetation information facilitates the evaluation of ecosystems and the improvement of remote sensing models. Extracting fractional vegetation cover (FVC) information using aerial images is one of the important areas of unmanned aerial vehicles. However, for a field with diverse vegetation species and a complex surface environment, FVC estimation still has difficulty guaranteeing accuracy. A segmented FVC calculation method based on a thresholding algorithm is proposed to improve the accuracy and speed of FVC estimation. The FVC estimation models were analyzed by randomly selected sample images using four vegetation indices: excess green, excess green minus excess red index, green leaf index, and red green blue vegetation index (RGBVI). The results showed that the empirical model method performed poorly (validating <jats:italic>R</jats:italic> <jats:sup>2</jats:sup> = 0.655 to 0.768). The isodata and triangle thresholding algorithms were introduced for vegetation segmentation, and their accuracy was analyzed. The results showed that the correlation between FVC estimation under RGBVI was the highest, and the triangle and isodata thresholding algorithms were complementary in terms of vegetation recognition accuracy, based on which a segmentation method of FVC calculation combining triangle and isodata algorithms was proposed. After testing, the accuracy of the improved FVC calculation method is higher than 90%, and the vegetation recognition accuracy is improved to more than 80%. This study is a positive guide to using digital cameras in field surveys.","PeriodicalId":48712,"journal":{"name":"Open Geosciences","volume":"16 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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