The Qinghai Nanshan fault is a larger fault in the Northeastern Xizang Plateau.In previous studies,its movement characteristics are mainly investigated with geological and seismic observations,and the tectonic transfo...The Qinghai Nanshan fault is a larger fault in the Northeastern Xizang Plateau.In previous studies,its movement characteristics are mainly investigated with geological and seismic observations,and the tectonic transformation role of the fault on its east is not yet clear.This study uses data fusion to obtain denser GPS observations near the Qinghai Nanshan fault.Based on tectonic characteristics,we establish a block model to investigate the fault slip rate,locking degree,and slip deficit.The results show that the Qinghai Nanshan fault slip rate is characterized by sinistral and convergent movement.Both the sinistral and convergent rates display a decreasing trend from west to east.The locking degree and slip deficit are higher in the western segment(with an average of about 0.74 and 1.1 mm/a)and lower in the eastern segment.Then,we construct a strain rate field using GPS observations to analyze the regional strain characteristics.The results indicate that along the fault,the western segment shows a larger shear strain rate and negative dilation rate.Regional earthquake records show that the frequency of earthquakes is lower near the fault.The joint results suggest that the western segment may have a higher earthquake risk.In addition,the insignificant fault slip rate in the eastern segment may indicate that it does not participate in the tectonic transformation among the Riyueshan,Lajishan,and West Qinling faults.展开更多
To overcome the high cost of learning,non-visual operation,and cumbersome steps of fine-tuning map elements in Generic Mapping Tools(GMT)and other geoscience mapping softwares,we present the Tectonic Geodesy Applicati...To overcome the high cost of learning,non-visual operation,and cumbersome steps of fine-tuning map elements in Generic Mapping Tools(GMT)and other geoscience mapping softwares,we present the Tectonic Geodesy Application(TGA),a user-friendly 64-bit tectonic geodesy mapping software based on the secondary development interface of the open source geographic information system QGIS.In this paper,we detailly introduce the architecture and function modules of our software,and highlight the functions of rendering and map decoration through four cases:the geologic map of Papua New Guinea,the seismicity in China and surrounding regions,the seismicity and crustal deformation of the Tibetan Plateau and the coseismic deformation of the 2017 Jiuzhaigou earthquake in China.Compared with GMT,the tectonic geodesy mapping software we developed has the advantages of simple operation,low learning cost and user-friendly interface.展开更多
On August 8,2017,an M_(W)6.5 earthquake occurred in Jiuzhaigou County,Sichuan Province,China,on the eastern margin of the Qinghai-Tibet Plateau.This study investigates the coseismic deformation field and fault model w...On August 8,2017,an M_(W)6.5 earthquake occurred in Jiuzhaigou County,Sichuan Province,China,on the eastern margin of the Qinghai-Tibet Plateau.This study investigates the coseismic deformation field and fault model with ascending and descending Sentinel-1 synthetic aperture radar(SAR)images,aftershock distribution,and elastic half-space dislocation model.The regional fault slip pattern is then quantita-tively examined using the boundary element method.The results show that the ascending and descending interferometric synthetic aperture radar(InSAR)coseismic deformation fields display an overall NNW-SSE trend,with more significant deformation on the southwest side of the fault.The coseismic fault geometry is divided into NW and SE sub-faults with strikes of 162.1°and 149.3°,respectively.The coseismic fault slip is dominated by a left-lateral strike-slip movement with an average rake of-2.31°,mainly occurring at a depth of 0-13.04 km with a shape of an approximately inverted triangle.The fault slip features two peak slip zones,with a maximum of 1.39 m.The total seismic moment is 6.34×10^(18) N·m(M_(W)6.47).The boundary element calculation quantitatively indicates that the regional fault slip pattern may be mainly attributable to the changing strike and dip.The strike changes from NNWeSSE to nearly NS direction,and the dip gradually decreases from the Jiuzhaigou earthquake fault in the north to the Huya fault in the south.With these characteristics,the Huya and the Jiuzhaigou earthquake faults form the eastern boundary of the Minshan uplift zone and accommodate the accumulated deformation.展开更多
Radar interferograms are usually influenced by factors such as atmospheric artifacts,orbital errors,and terrain errors.It is difficult to reduce the influence by using the conventional small baseline subset(SBAS)metho...Radar interferograms are usually influenced by factors such as atmospheric artifacts,orbital errors,and terrain errors.It is difficult to reduce the influence by using the conventional small baseline subset(SBAS)method when determining the deformation rate.This study uses the adjustment model with systematic parameters to improve the conventional SBAS method and employs it to determine the interseismic deformation rate of the Haiyuan fault system,providing a data reference for exploring the locking depth,strain accumulation state,and potential seismic risk assessment of different segments of the Haiyuan fault system.The results are as follows:(1)the simulation experiment verifies the feasibility and robustness of the modified SBAS method.This method can effectively reduce the influence of residual signals such as atmospheric artifacts,orbital errors and terrain errors in the interferograms.The deformation rate map can be significantly improved;(2)the deformation rate field in the radar’s Line of Sight(LOS)direction shows that there are obvious differences between the north and south sides of Haiyuan fault system,which is consistent with the characteristics of the left-lateral strike-slip movement of the Haiyuan fault system.The deformation rate field and profiles reflect the complex trends among different segments of Haiyuan fault system in detail.(3)the deformation rate of the Jingtai pull-apart basin is higher than that of the surrounding areas,possibly indicating strong regional activity,which provides a reference for studying the seismic risk of the Jingtai pull-apart basin;and(4)the interseismic deformation rate and profiles across the fault show that the middle section of the Lao Hu Shan(LHS)segment and the western and middle sections of the Haiyuan segment are locked.展开更多
The M_(W)7.1 Anchorage earthquake is the most destructive earthquake since the 1964 M_(W)9.2 great Alaska earthquake in the United States.In this study,high-rate GPS data and near-field broadband seismograms are used ...The M_(W)7.1 Anchorage earthquake is the most destructive earthquake since the 1964 M_(W)9.2 great Alaska earthquake in the United States.In this study,high-rate GPS data and near-field broadband seismograms are used in separate and joint inversions by the generalized Cut-and-Paste(gCAP)method to estimate the focal mechanism.In order to investigate the influence of crustal velocity structure on the focal mechanism inversion results,two velocity models(Crustl.0 and Alaska Earthquake Center(AEC))are used for detailed comparison and analysis.The results show that:(1)The two nodal planes of the optimal double-couple solution are nearly north-south striking,with dip angles of about 30°and 60°respectively,and the centroid focal depth is 54-55 km,which is an intraplate normal fault event.(2)The inversion results for the two types of data and the two velocity models are consistent with some previous studies,which indicates that the results are stable and reliable.The more accurate velocity structure model is helpful for focal mechanism inversion of the complex earthquake.(3)The inclusion of high-rate GPS data in joint inversion provides a more effective constraint on centroid depth.展开更多
As an important model for explaining the seismic rupture mode,the asperity model plays an important role in studying the stress accumulation of faults and the location of earthquake initiation.Taking Qilian-Haiyuan fa...As an important model for explaining the seismic rupture mode,the asperity model plays an important role in studying the stress accumulation of faults and the location of earthquake initiation.Taking Qilian-Haiyuan fault as an example,this paper combines geodetic method and b-value method to propose a multi-source observation data fusion detection method that accurately determines the asperity boundary named dual threshold search method.The method is based on the criterion that the b-value asperity boundary should be most consistent with the slip deficit rate asperity boundary.Then the optimal threshold combination of slip deficit rate and b-value is obtained through threshold search,which can be used to determine the boundary of the asperity.Based on this method,the study finds that there are four potential asperities on the Qilian-Haiyuan fault:two asperities(A1 and A2)are on the Tuolaishan segment and the other two asperities(B and C)are on Lenglongling segment and Jinqianghe segment,respectively.Among them,the lengths of asperities A1 and A2 on Tuolaishan segment are 17.0 km and 64.8 km,respectively.And the lower boundaries are 5.5 km and 15.5 km,respectively;The length of asperity B on Lenglongling segment is 70.7 km,and the lower boundary is 10.2 km.The length of asperity C on Jinqianghe segment is 42.3 km,and the lower boundary is 8.3 km.展开更多
基金supported by the National Natural Science Foundation of China(41874011,42074007)the Fundamental Research Funds for the Central Universities(2042023kfyq01)。
文摘The Qinghai Nanshan fault is a larger fault in the Northeastern Xizang Plateau.In previous studies,its movement characteristics are mainly investigated with geological and seismic observations,and the tectonic transformation role of the fault on its east is not yet clear.This study uses data fusion to obtain denser GPS observations near the Qinghai Nanshan fault.Based on tectonic characteristics,we establish a block model to investigate the fault slip rate,locking degree,and slip deficit.The results show that the Qinghai Nanshan fault slip rate is characterized by sinistral and convergent movement.Both the sinistral and convergent rates display a decreasing trend from west to east.The locking degree and slip deficit are higher in the western segment(with an average of about 0.74 and 1.1 mm/a)and lower in the eastern segment.Then,we construct a strain rate field using GPS observations to analyze the regional strain characteristics.The results indicate that along the fault,the western segment shows a larger shear strain rate and negative dilation rate.Regional earthquake records show that the frequency of earthquakes is lower near the fault.The joint results suggest that the western segment may have a higher earthquake risk.In addition,the insignificant fault slip rate in the eastern segment may indicate that it does not participate in the tectonic transformation among the Riyueshan,Lajishan,and West Qinling faults.
基金supported by the NSFC projects(Grant Nos:41431069,41574002and 41721003).
文摘To overcome the high cost of learning,non-visual operation,and cumbersome steps of fine-tuning map elements in Generic Mapping Tools(GMT)and other geoscience mapping softwares,we present the Tectonic Geodesy Application(TGA),a user-friendly 64-bit tectonic geodesy mapping software based on the secondary development interface of the open source geographic information system QGIS.In this paper,we detailly introduce the architecture and function modules of our software,and highlight the functions of rendering and map decoration through four cases:the geologic map of Papua New Guinea,the seismicity in China and surrounding regions,the seismicity and crustal deformation of the Tibetan Plateau and the coseismic deformation of the 2017 Jiuzhaigou earthquake in China.Compared with GMT,the tectonic geodesy mapping software we developed has the advantages of simple operation,low learning cost and user-friendly interface.
基金This work was supported by the National Key Research and Development Program of China(2018YFC1503603,2016YFB0501405)the National Natural Science Foundation of China(41874011,41774011)。
文摘On August 8,2017,an M_(W)6.5 earthquake occurred in Jiuzhaigou County,Sichuan Province,China,on the eastern margin of the Qinghai-Tibet Plateau.This study investigates the coseismic deformation field and fault model with ascending and descending Sentinel-1 synthetic aperture radar(SAR)images,aftershock distribution,and elastic half-space dislocation model.The regional fault slip pattern is then quantita-tively examined using the boundary element method.The results show that the ascending and descending interferometric synthetic aperture radar(InSAR)coseismic deformation fields display an overall NNW-SSE trend,with more significant deformation on the southwest side of the fault.The coseismic fault geometry is divided into NW and SE sub-faults with strikes of 162.1°and 149.3°,respectively.The coseismic fault slip is dominated by a left-lateral strike-slip movement with an average rake of-2.31°,mainly occurring at a depth of 0-13.04 km with a shape of an approximately inverted triangle.The fault slip features two peak slip zones,with a maximum of 1.39 m.The total seismic moment is 6.34×10^(18) N·m(M_(W)6.47).The boundary element calculation quantitatively indicates that the regional fault slip pattern may be mainly attributable to the changing strike and dip.The strike changes from NNWeSSE to nearly NS direction,and the dip gradually decreases from the Jiuzhaigou earthquake fault in the north to the Huya fault in the south.With these characteristics,the Huya and the Jiuzhaigou earthquake faults form the eastern boundary of the Minshan uplift zone and accommodate the accumulated deformation.
基金supported by the National Natural Science Foundation of China(41874011,41861134009)the National Key Research and Development Program of China(2018YFC1503603)
文摘Radar interferograms are usually influenced by factors such as atmospheric artifacts,orbital errors,and terrain errors.It is difficult to reduce the influence by using the conventional small baseline subset(SBAS)method when determining the deformation rate.This study uses the adjustment model with systematic parameters to improve the conventional SBAS method and employs it to determine the interseismic deformation rate of the Haiyuan fault system,providing a data reference for exploring the locking depth,strain accumulation state,and potential seismic risk assessment of different segments of the Haiyuan fault system.The results are as follows:(1)the simulation experiment verifies the feasibility and robustness of the modified SBAS method.This method can effectively reduce the influence of residual signals such as atmospheric artifacts,orbital errors and terrain errors in the interferograms.The deformation rate map can be significantly improved;(2)the deformation rate field in the radar’s Line of Sight(LOS)direction shows that there are obvious differences between the north and south sides of Haiyuan fault system,which is consistent with the characteristics of the left-lateral strike-slip movement of the Haiyuan fault system.The deformation rate field and profiles reflect the complex trends among different segments of Haiyuan fault system in detail.(3)the deformation rate of the Jingtai pull-apart basin is higher than that of the surrounding areas,possibly indicating strong regional activity,which provides a reference for studying the seismic risk of the Jingtai pull-apart basin;and(4)the interseismic deformation rate and profiles across the fault show that the middle section of the Lao Hu Shan(LHS)segment and the western and middle sections of the Haiyuan segment are locked.
基金co-supported by the National Natural Science Foundation of China under Grants No.41721003,No.42074007the National Key Research and Development Program of China under Grant No.2018YFC1503604。
文摘The M_(W)7.1 Anchorage earthquake is the most destructive earthquake since the 1964 M_(W)9.2 great Alaska earthquake in the United States.In this study,high-rate GPS data and near-field broadband seismograms are used in separate and joint inversions by the generalized Cut-and-Paste(gCAP)method to estimate the focal mechanism.In order to investigate the influence of crustal velocity structure on the focal mechanism inversion results,two velocity models(Crustl.0 and Alaska Earthquake Center(AEC))are used for detailed comparison and analysis.The results show that:(1)The two nodal planes of the optimal double-couple solution are nearly north-south striking,with dip angles of about 30°and 60°respectively,and the centroid focal depth is 54-55 km,which is an intraplate normal fault event.(2)The inversion results for the two types of data and the two velocity models are consistent with some previous studies,which indicates that the results are stable and reliable.The more accurate velocity structure model is helpful for focal mechanism inversion of the complex earthquake.(3)The inclusion of high-rate GPS data in joint inversion provides a more effective constraint on centroid depth.
基金This work is supported by the National Key Research and Development Plan of China under Grants No.2018YFC1503604the National Natural Science Foundation of China under Grants No.41721003,No.42074007the Key Laboratory of Geospace Environment and Geodesy,Ministry of Education,Wuhan University,No.19-01-08。
文摘As an important model for explaining the seismic rupture mode,the asperity model plays an important role in studying the stress accumulation of faults and the location of earthquake initiation.Taking Qilian-Haiyuan fault as an example,this paper combines geodetic method and b-value method to propose a multi-source observation data fusion detection method that accurately determines the asperity boundary named dual threshold search method.The method is based on the criterion that the b-value asperity boundary should be most consistent with the slip deficit rate asperity boundary.Then the optimal threshold combination of slip deficit rate and b-value is obtained through threshold search,which can be used to determine the boundary of the asperity.Based on this method,the study finds that there are four potential asperities on the Qilian-Haiyuan fault:two asperities(A1 and A2)are on the Tuolaishan segment and the other two asperities(B and C)are on Lenglongling segment and Jinqianghe segment,respectively.Among them,the lengths of asperities A1 and A2 on Tuolaishan segment are 17.0 km and 64.8 km,respectively.And the lower boundaries are 5.5 km and 15.5 km,respectively;The length of asperity B on Lenglongling segment is 70.7 km,and the lower boundary is 10.2 km.The length of asperity C on Jinqianghe segment is 42.3 km,and the lower boundary is 8.3 km.
