In slowly deforming intraplate regions,identifying active faults is challenging due to their low slip rates or concealment by recent sedimentation and anthropogenic activity,requiring significant time and resources.We...In slowly deforming intraplate regions,identifying active faults is challenging due to their low slip rates or concealment by recent sedimentation and anthropogenic activity,requiring significant time and resources.We focus on the structural features and spatial extent of a buried active reverse fault,central South Korea.Our approach integrates the structural and paleoseismic records from the fault exposure with 2D and 3D electrical resistivity surveys.In the road construction area,electrical resistivity differentiates the fault’s hanging wall from the footwall in granitic bedrock.展开更多
Transpression occurs in response to oblique convergence across a deformation zone in intraplate regions and plate boundaries.The Korean Peninsula is located at an intraplate region of the eastern Eurasian Plate and ha...Transpression occurs in response to oblique convergence across a deformation zone in intraplate regions and plate boundaries.The Korean Peninsula is located at an intraplate region of the eastern Eurasian Plate and has been deformed under the ENE–WSW maximum horizontal compression since the late Pliocene.In this study,we analyzed short-term instrumental seismic(focal mechanism)and long-term paleoseis-mic(Quaternary fault outcrop)data to decipher the neotectonic crustal deformation pattern in the south-eastern Korean Peninsula.Available(paleo-)seismic data acquired from an NNE–SSW trending deformation zone between the Yangsan and Ulleung fault zones indicate spatial partitioning of crustal deformation by NNW–SSE to NNE–SSW striking reverse faults and NNE–SSW striking strike-slip faults,supporting a strike-slip partitioned transpression model.The instantaneous and finite neotectonic strains,estimated from the focal mechanism and Quaternary outcrop data,respectively,show discrepan-cies in their axes,which can be attributed to the switching between extensional and intermediate axes of finite strain during the accumulation of wrench-dominated transpression.Notably,some major faults,including the Yangsan and Ulsan fault zones,are relatively misoriented to slip under the current stress condition but,paradoxically,have more(paleo-)seismic records indicating their role in accommodating the neotectonic transpressional strain.We propose that fluids,heat flow,and lithospheric structure are potential factors affecting the reactivation of the relatively misoriented major faults.Our findings provide insights into the accommodation pattern of strain associated with the neotectonic crustal extrusion in an intraplate region of the eastern Eurasian Plate in response to the collision of the Indian Plate and the sub-duction of the Pacific/Philippine Sea Plates.展开更多
基金supported by a grant(2022-MOIS62-001)for National Disaster Risk Analysis and Management Technology in Earthquakes funded by the Ministry of Interior and Safety(MOIS,South Korea).
文摘In slowly deforming intraplate regions,identifying active faults is challenging due to their low slip rates or concealment by recent sedimentation and anthropogenic activity,requiring significant time and resources.We focus on the structural features and spatial extent of a buried active reverse fault,central South Korea.Our approach integrates the structural and paleoseismic records from the fault exposure with 2D and 3D electrical resistivity surveys.In the road construction area,electrical resistivity differentiates the fault’s hanging wall from the footwall in granitic bedrock.
基金This research was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant(no.20212010200020)the Energy&Mineral Resources Develop-ment Association of Korea(EMRD)grant(Datascience based oil/gas exploration consortium),funded by the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea.
文摘Transpression occurs in response to oblique convergence across a deformation zone in intraplate regions and plate boundaries.The Korean Peninsula is located at an intraplate region of the eastern Eurasian Plate and has been deformed under the ENE–WSW maximum horizontal compression since the late Pliocene.In this study,we analyzed short-term instrumental seismic(focal mechanism)and long-term paleoseis-mic(Quaternary fault outcrop)data to decipher the neotectonic crustal deformation pattern in the south-eastern Korean Peninsula.Available(paleo-)seismic data acquired from an NNE–SSW trending deformation zone between the Yangsan and Ulleung fault zones indicate spatial partitioning of crustal deformation by NNW–SSE to NNE–SSW striking reverse faults and NNE–SSW striking strike-slip faults,supporting a strike-slip partitioned transpression model.The instantaneous and finite neotectonic strains,estimated from the focal mechanism and Quaternary outcrop data,respectively,show discrepan-cies in their axes,which can be attributed to the switching between extensional and intermediate axes of finite strain during the accumulation of wrench-dominated transpression.Notably,some major faults,including the Yangsan and Ulsan fault zones,are relatively misoriented to slip under the current stress condition but,paradoxically,have more(paleo-)seismic records indicating their role in accommodating the neotectonic transpressional strain.We propose that fluids,heat flow,and lithospheric structure are potential factors affecting the reactivation of the relatively misoriented major faults.Our findings provide insights into the accommodation pattern of strain associated with the neotectonic crustal extrusion in an intraplate region of the eastern Eurasian Plate in response to the collision of the Indian Plate and the sub-duction of the Pacific/Philippine Sea Plates.
