High-level radioactive waste should be isolated from humans and society for over 100,000 years.Several factors should be considered for a geologically stable disposal site such as topography,faults,seismic activity,an...High-level radioactive waste should be isolated from humans and society for over 100,000 years.Several factors should be considered for a geologically stable disposal site such as topography,faults,seismic activity,and hydrological properties.Brittle structures within the bedrock,such as faults,act as potential flow pathways for radioactive isotopes as well as significantly influence bedrock stability in the context of future seismicity.However,studies on fault behavior and deformation in underground settings,which are key components for site characterization,are relatively scarce compared with those at the surface.This study was conducted within the KAERI Underground Research Tunnel(KURT),an experimental tunnel focused on comprehending the structural evolution and designing nuclear waste disposal sites.To conduct a comprehensive structural study aimed at reconstructing the structural evolution of the study area in space and time,a preliminary lineament analysis was conducted using a length-weighted lineament analysis.Furthermore,kinematic analysis was conducted based on a cross-cutting relationship to establish the deformation history and change of paleostress condition.We identified three distinct brittle deformation stages evolving from a strike-slip to an extensional regime associated with the change of the maximum horizontal stress from ENE–WSW through NW–SE to NNE–SSW.This study underscored that a detailed study combining remote sensing lineament analysis,field structural surveys,and paleostress analysis could integrate and improve previously proposed methods for the selection of deep geological repositories.展开更多
Deformed soft-sediment deformation structures(SSDS)can indicate polyphase deformation events and provide valuable insights into the inversion process of a basin.Herein,we present the Miocene–Quaternary deformation in...Deformed soft-sediment deformation structures(SSDS)can indicate polyphase deformation events and provide valuable insights into the inversion process of a basin.Herein,we present the Miocene–Quaternary deformation inversion history of the Bomun sub-basin in the Gyeongju area of SE Korea.The inferred ENE compression direction(σHmax)based on paleostress analysis of the fault system,displacing Miocene sediments and SSDS,corresponds to the current stress field.The widespread occurrence of clear liquefaction structures and the vertical repetition of SSDS indicate substantial seismic activity during the basin opening stage.Brittle deformation features observed at both outcrop-and microstructural-scale along the faults suggest a reactivation as reverse faulting associated with a tilting process.The tectonic history of the study area is distinguished by SSDS associated with seismic activity,and reverse faulting associated with inversion process under ENE orientedσHmax.The Environmental Seismic Intensity Scale(ESI-07)based on the SSDS indicates seismic intensity of IX-X,which might be related with the opening of the Bomun sub-basin.Therefore,detailed analyses of SSDS could provide valuable insights on the dynamics of local geology and contribute to further extensive research on seismic hazards and basin inversion.展开更多
基金supported by the Institute for Korea Spent Nuclear Fuel(iKSNF)National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT,MSIT)(No.2021M2E1A1085200).
文摘High-level radioactive waste should be isolated from humans and society for over 100,000 years.Several factors should be considered for a geologically stable disposal site such as topography,faults,seismic activity,and hydrological properties.Brittle structures within the bedrock,such as faults,act as potential flow pathways for radioactive isotopes as well as significantly influence bedrock stability in the context of future seismicity.However,studies on fault behavior and deformation in underground settings,which are key components for site characterization,are relatively scarce compared with those at the surface.This study was conducted within the KAERI Underground Research Tunnel(KURT),an experimental tunnel focused on comprehending the structural evolution and designing nuclear waste disposal sites.To conduct a comprehensive structural study aimed at reconstructing the structural evolution of the study area in space and time,a preliminary lineament analysis was conducted using a length-weighted lineament analysis.Furthermore,kinematic analysis was conducted based on a cross-cutting relationship to establish the deformation history and change of paleostress condition.We identified three distinct brittle deformation stages evolving from a strike-slip to an extensional regime associated with the change of the maximum horizontal stress from ENE–WSW through NW–SE to NNE–SSW.This study underscored that a detailed study combining remote sensing lineament analysis,field structural surveys,and paleostress analysis could integrate and improve previously proposed methods for the selection of deep geological repositories.
基金supported by a grant(2022-MOIS62-001(RS-2022-ND640011))from the National Disaster Risk AnalysisManagement Technology in Earthquake funded by the Ministry of Interior and Safety(MOIS,Korea).
文摘Deformed soft-sediment deformation structures(SSDS)can indicate polyphase deformation events and provide valuable insights into the inversion process of a basin.Herein,we present the Miocene–Quaternary deformation inversion history of the Bomun sub-basin in the Gyeongju area of SE Korea.The inferred ENE compression direction(σHmax)based on paleostress analysis of the fault system,displacing Miocene sediments and SSDS,corresponds to the current stress field.The widespread occurrence of clear liquefaction structures and the vertical repetition of SSDS indicate substantial seismic activity during the basin opening stage.Brittle deformation features observed at both outcrop-and microstructural-scale along the faults suggest a reactivation as reverse faulting associated with a tilting process.The tectonic history of the study area is distinguished by SSDS associated with seismic activity,and reverse faulting associated with inversion process under ENE orientedσHmax.The Environmental Seismic Intensity Scale(ESI-07)based on the SSDS indicates seismic intensity of IX-X,which might be related with the opening of the Bomun sub-basin.Therefore,detailed analyses of SSDS could provide valuable insights on the dynamics of local geology and contribute to further extensive research on seismic hazards and basin inversion.
