The yangtze River Three Gorges Project is the largest water-conservancy project in the world. After its completion in 2009, its total installed capacity Will be 18.25 million kW With an annual power generation of 84. ...The yangtze River Three Gorges Project is the largest water-conservancy project in the world. After its completion in 2009, its total installed capacity Will be 18.25 million kW With an annual power generation of 84. 7 billion kWh. The total storage capacity will be 39.3 billion cubic meters, and the anti-flood storage capacity Will be 22. 15 billion cubic meters. The project will effectively control flooding along the Y8ngtZe River protect 1.53 million hectares of land, protect the life and property of 15 million people in the middle and lower reaches of the Yangtze River and improve the river’s transportation capacity Many are concerned about the inhabitants in the reservoir area who have to be relocated. According to statistics, over the 17-year construction period, 1.038 million Chongqing people will be relocated, comprising 85 percent of the total number of people who have to be relocated. Such grand scale relocation has rarely been seen in the history of China and the world. To gain a better understanding of the relocation process, staff reporter Wang Xin visited some relocated settlements and interviewed Gan Yuping, vice mayor of Chongqing Municipality and head of the relocation project.展开更多
The three-dimensional(3D)geometry of a fault is a critical control on earthquake nucleation,dynamic rupture,stress triggering,and related seismic hazards.Therefore,a 3D model of an active fault can significantly impro...The three-dimensional(3D)geometry of a fault is a critical control on earthquake nucleation,dynamic rupture,stress triggering,and related seismic hazards.Therefore,a 3D model of an active fault can significantly improve our understanding of seismogenesis and our ability to evaluate seismic hazards.Utilising the SKUA GoCAD software,we constructed detailed seismic fault models for the 2021 M_(S)6.4 Yangbi earthquake in Yunnan,China,using two sets of relocated earthquake catalogs and focal mechanism solutions following a convenient 3D fault modeling workflow.Our analysis revealed a NW-striking main fault with a high-angle SW dip,accompanied by two branch faults.Interpretation of one dataset revealed a single NNW-striking branch fault SW of the main fault,whereas the other dataset indicated four steep NNE-striking segments with a left-echelon pattern.Additionally,a third ENE-striking short fault was identified NE of the main fault.In combination with the spatial distribution of pre-existing faults,our 3D fault models indicate that the Yangbi earthquake reactivated pre-existing NW-and NE-striking fault directions rather than the surface-exposed Weixi-Qiaohou-Weishan Fault zone.The occurrence of the Yangbi earthquake demonstrates that the reactivation of pre-existing faults away from active fault zones,through either cascade or conjugate rupture modes,can cause unexpected moderate-large earthquakes and severe disasters,necessitating attention in regions like southeast Xizang,which have complex fault systems.展开更多
On December 18,2023,an M_(s)6.2 earthquake jolted Jishishan County in the Linxia Hui Autonomous Prefecture in Northwest China's Gansu Province,causing substantial casualties and building collapses.The earthquake o...On December 18,2023,an M_(s)6.2 earthquake jolted Jishishan County in the Linxia Hui Autonomous Prefecture in Northwest China's Gansu Province,causing substantial casualties and building collapses.The earthquake occurred in the Qilian Block on the northeastern border of the Qinghai-Tibet Plateau,where faults are highly active and the geological structure is complex.In this study,we utilized methods such as relocation,focal mechanism solutions,and earthquake rupture processes to describe seismogenic faults.The results indicated that the majority of aftershocks occurred at a depth of 12 km.The centroid depth of the main shock and the depth of the maximum rupture point during the rupture process were also 12 km.Various geophysical methods exhibited a high degree of consistency in depth exploration.Aftershocks were distributed mainly to the west and north of the main shock and extended in the NNW direction,primarily through unilateral rupture.The main shock was a reverse thrust event with a small dextral strike-slip component.In this study,more regional data,such as previous GPS observations,field geological observations,and the distributions of the primary stress states in the region,were also incorporated.We inferred that the main shock was triggered by the main fault at the northern margin of the Lajishan Fault and that the movement of the main fault also activated some secondary faults.The compressive forces on both sides of the Lajishan Fault Zone led to the uplift of mountain areas,accompanied by some landslides,leading to this catastrophic earthquake event.In this article,the activity relationships among the 2022 M_(s)6.9 Menyuan earthquake,the 2019 M_(s)5.7 Xiahe earthquake,and the Jishishan earthquake under the action of regional stress are also discussed.This study provides additional evidence and new ideas for exploring the seismogenic process of the Lajishan Fault Zone and has implications for future in-depth research on underground activity in this region.展开更多
The December 18,2023,M_(S)6.2 Jishishan earthquake occurred along the northeastern margin of the Qinghai-Xizang Plateau within the Laji-Jishi Shan Fault Zone(LJSFZ),a complex thrust-dominated tectonic belt.To identify...The December 18,2023,M_(S)6.2 Jishishan earthquake occurred along the northeastern margin of the Qinghai-Xizang Plateau within the Laji-Jishi Shan Fault Zone(LJSFZ),a complex thrust-dominated tectonic belt.To identify the seismogenic fault and better understand the regional tectonic framework,we integrated high-resolution Digital Elevation Models(DEMs)derived from GF-7 stereo satellite and Unmanned Aerial Vehicle(UAV)photogrammetry,relocated aftershock sequences,and conducted detailed field investigations.Our results identify four Late Quaternary thrust faults(F1-1 to F1-4),among which the Zhaomuchuan fault(F1-3),a NE-dipping back-thrust,aligns closely with the main-shock and aftershock distribution and exhibits clear Holocene activity.Seismic relocation reveals a NEdipping seismogenic zone at depths of 5-12 km,consistent with a shallow reverse-faulting mechanism under WSW-ENE oblique compression.Structural analysis and cross-sectional profiles suggest that fault F1-3 propagates into a mid-crustal detachment surface,forming a foreland-vergent thrust-nappe system.Importantly,the rupture of this secondary fault,rather than the locked primary boundary fault F1-1,indicates stress transfer and localization within a critically tapered wedge,consistent with global analogs of back-thrust-dominated earthquakes.These findings underscore the seismotectonic complexity of the LJSFZ and highlight the significant seismic hazard posed by subsidiary structures in compressional settings.展开更多
The widespread variation of focal depths and fault plane solutions observed in the Hindukush region depicts continuous deformation along the Indian-Eurasian collision zone.For period of twelve years i.e.from 2010 to 2...The widespread variation of focal depths and fault plane solutions observed in the Hindukush region depicts continuous deformation along the Indian-Eurasian collision zone.For period of twelve years i.e.from 2010 to 2022,a total of 89 intermediate-depth earthquakes of magnitude(Mw)≥5.5 of the Hindukush Region were considered,relocated using both regional and tele seismic data with 90 per cent confidence limits of less than 20 km.Two distinct seismic activity clusters:First one at a deeper depth and second at a shallower depth having different P-axes were observed that verifies the internal structure and geometry of Hindukush zone as suggested in previous studies.Beneath the Hindukush collision zone,there exists a complex pattern of deformation,arising from a combination of compression,tension,shearing and necking states due to an unusual and a rare case of subduction that is not from oceanic plate.The Hindukush seismic zone extends from 70 to 300 km depth and mostly strikes east-west and then turns northeast.The relocated seismicity by merging data of seismic network close to Hindukush along with international data shows that the Hindukush zone may be divided vertically into upper and lower slabs separated by a gap at about 150 km depth at which strike and dip directions change sharply with significant structural changes.Seismicity rate is higher in the lower part of Hindukush,having large magnitude events in a small volume below 180 km forming complex pattern of source mechanisms.Contrary in upper part seismicity rate is lower and scattered.The Global CMT(Global Centroid-Moment-Tensor Project)source mechanisms of intermediate depth earthquakes have a systematic pattern of reverse faulting with the vertical T-axes,while shallow events do not have such pattern.The vertical T-axes of the intermediate-depth events may be attributed to negative buoyancy caused by subduction of the cold and denser slab.展开更多
As a crucial pivot for national strategic development,the university relocation project in Xiong’an New Area undertakes the mission of optimizing capital functions and promoting regional coordinated development.Takin...As a crucial pivot for national strategic development,the university relocation project in Xiong’an New Area undertakes the mission of optimizing capital functions and promoting regional coordinated development.Taking the Xi-ong’an Campus of China University of Geosciences(Beijing)as a case study,this paper explores the collaborative pa-thways between universities and cities in terms of functional complementarity,resource sharing,and ecological symbiosis from the perspective of campus functional layout and spatial optimization.By integrating four core concepts—green ecology,intelligent technology,cultural inheritance,and traffic optimization—it proposes a design strategy of“breaking boundaries and multi-dimensional linkage,”aiming to construct a new spatial paradigm of urban-university integration and provide theoretical support and practical references for the development of higher education and urbanization in Xiong’an New Area.展开更多
The epicenter of the Luxian M_(S)6.0 earthquake on September 16,2021,was located in the southern Sichuan Basin,which is a historically seismically quiescent area.In recent years,the frequency of earthquakes has increa...The epicenter of the Luxian M_(S)6.0 earthquake on September 16,2021,was located in the southern Sichuan Basin,which is a historically seismically quiescent area.In recent years,the frequency of earthquakes has increased with the large-scale exploitation of shale gas.No evident surface fractures or seismic faults were observed after the Luxian earthquake.Based on high-quality data recorded by a dense seismic array composed of 70 portable stations with an average spacing of 2-3 km,a highresolution seismic catalog was constructed for 7 days before and 36 days after the M_(S)6.0 earthquake using LOC-FLOW,an effective workflow of phase picking,phase association,and earthquake location.Based on the new earthquake catalog,four earthquake clusters that occurred within the Yujiasi Syncline during this period were identified.Among them,the M_(S)6.0 main earthquake sequence had a NW-SE trend and inclined towards the SW,with a length of approximately 8 km and width of 5 km.The M_(S)6.0 earthquake sequence only appeared after the mainshock.The other three clusters were located in the northeast direction of the M_(S)6.0 earthquake sequence,all of which were NE-SW trending strips and had no evident direct correlation with the M_(S)6.0 mainshock.The focal depth was concentrated in the range of 2-7 km.Based on the seismic sequence profile and structural background,the M_(S)6.0 seismic structure may be a blind buried fault zone with a NW strike composed of multiple small conjugate faults with NE and SW dip.The fault was not exposed on the surface and was related to the detachment structure in the deep part of the Sichuan Basin.展开更多
Stepping into Donglong Group’s intelligent factory in the Yangtze River Delta,the automated production lines is transforming fluffy down into premium home textiles export to Europe and America.At a pivotal moment of ...Stepping into Donglong Group’s intelligent factory in the Yangtze River Delta,the automated production lines is transforming fluffy down into premium home textiles export to Europe and America.At a pivotal moment of global supply chain restructuring,this homegrown textile and apparel exporter is answering a critical question:How can Chinese textile companies sustain their competitive edge amid tariff barriers and supply chain relocation?展开更多
A new method, named relocation, was proposed to reduce the impact of sensor errors systematically, especially whenavailable data of sensors are abundant. The procedure includes evaluating the reliability of every sens...A new method, named relocation, was proposed to reduce the impact of sensor errors systematically, especially whenavailable data of sensors are abundant. The procedure includes evaluating the reliability of every sensors datum, processing the initiallocation by the credible data, and selecting a set of equations with optimal noise tolerance according to the relative relationshipbetween the initial location and sensors location, then calculating the final location by k-mean voting. The results obtained in thisresearch include comparing traditional location method with the presented method in both simulation and field experiment. In thefield experiment, the location error of relocation method reduced 41.8% compared with traditional location method. The resultssuggested that relocation method can improve the fault-tolerant performance significantly.展开更多
By investigating present relocation residential districts for peasants whose houses are removed for the unified planning of rural areas in north Jiangsu Province, as well as residents' feelings about the environme...By investigating present relocation residential districts for peasants whose houses are removed for the unified planning of rural areas in north Jiangsu Province, as well as residents' feelings about the environment of residential district, main architectural structures and energy consumption conditions, the indoor thermal environment, use of main heating and cooling facilities, residents' satisfaction on the acoustical and luminous environment, major space-enclosing structures and calculation of energy-saving designs are analyzed, and suggestions are given for the architectural design of relocation residential districts in the study area. It is stressed that the relationship between energy conservation and architectural layout, orientation, lighting, ventilation, selection of enclosing-structure materials, facade, color and style should be properly handled in the planning, and the focus is to control building orientation and shape coefficient, on the basis of which energy-saving designs of windows, exterior walls and roofs can be done. Energy consumption of present residential buildings is calculated and analyzed to bring forth new ideas to the energy-saving designs for relocation residential districts in north Jiangsu Province, and establish an architectural energy-saving system suitable for climatic and natural conditions of north Jiangsu to instruct the energy-saving designs of relocation residential districts in the study area.展开更多
Locating an earthquakes focal depth is always a key project in seismology. Precise focal depth is of critical importance for evaluating seismic hazards, deciphering dynamic mechanisms of earthquake generating,estima...Locating an earthquakes focal depth is always a key project in seismology. Precise focal depth is of critical importance for evaluating seismic hazards, deciphering dynamic mechanisms of earthquake generating,estimating aftershock evolutions and risk,as well as monitoring nuclear tests. However,how we determine an accurate focal depth is always a challenge in seismological studies. Aiming to solve these problems, we analyzed and summarized the present status and the future development of earthquake focal depth locating. In this paper we first reviewed the present status of focal depth locating in the world,and summarized the frequently-used relocating methods and ideas at present,and introduced two types of focal depth relocating ideas: arrival time relocating and waveform modeling methods. For these ideas,we systematically described the S-P and the Pn-Pg methods that belong to arrival time method,and polarization focal depth locating and amplitude focal depth locating that belongs to waveform modeling,and further analyzed the advantages and limitations of these methods. Since the depth phase methods are highly sensitive to focal depth,and are relatively free from the uncertainties of crustal models,we mainly reviewed the depth phases of s Pm P,s PL,s Pn,and s Sn,and quantitatively evaluated their availabilities and characteristics. Second,we also discussed the effects of crustal velocity models on the reliability of focal depth locating,and reviewed the advancements of seismic tomography techniques over recent years. Finally,based on the present status of the progress on the focal depth locating,and studies of seismic velocity structures,we proposed an idea of combining multiple datasets and relocating methods,jointly utilizing seismologic and geodetic techniques to relocate focal depth,which should be the major research field in investigating focal depth and source parameters in the near future.展开更多
Based on the construction property of rolled compacted concrete, three-dimensional finite element relocating mesh method was developed in simulating construction process and computing temperature and stress field. Usi...Based on the construction property of rolled compacted concrete, three-dimensional finite element relocating mesh method was developed in simulating construction process and computing temperature and stress field. Using this method, the temperature and the thermal stress fields developed in the RCC gravity dam of the Longtan project with or without a longitudinal joint during construction and operation are calculated so as to simulate the construction process. The computation results show that the value of the thermal stresses developed in the dam even, without any longitudinal joint, could meet the design criteria provided the placement temperature is adequately controlled.展开更多
According to the construction characteristic of RCC dam cast by layers, three-dimensional finite element relocating mesh method is developed to simulate construction process and compute temperature field. The computat...According to the construction characteristic of RCC dam cast by layers, three-dimensional finite element relocating mesh method is developed to simulate construction process and compute temperature field. The computation model of relocating mesh method is expatiated in detail; based on the thermodynamic properties of RCC materials, the feasibility and error of relocating mesh method are analyzed and demonstrated; The computation results in this article are verified by means of the temperature observation data of certain RCC gravity dam. The results show that the temperature field computed by three-dimensional finite element relocating mesh method can not only ensure the computation precision, but also improve the calculation efficiency greatly. This provides an effective method for simulating construction process and computing temperature field of RCC dam.展开更多
In this paper, regarding the actual conditions of a roller compacted concrete dam, three-dimensional finite element relocating mesh method is utilized to simulate and calculate the temperature field of the RCC dam dur...In this paper, regarding the actual conditions of a roller compacted concrete dam, three-dimensional finite element relocating mesh method is utilized to simulate and calculate the temperature field of the RCC dam during the construction stage and operating period. The calculation is well consistent with the actual construction process, the thin-layer pouring process the pouring temperature and all kinds of external loads involved being taken into account, By comparing and analyzing of the impact of the cold wave on the dam stress, important references are provided for the RCCD design and the temperature control during construction.展开更多
This paper analyses the impact of the poverty alleviation relocation(PAR)program on rural household income and evaluates the heterogeneous income effects of various relocation modes,based on a panel dataset of relocat...This paper analyses the impact of the poverty alleviation relocation(PAR)program on rural household income and evaluates the heterogeneous income effects of various relocation modes,based on a panel dataset of relocated households from 16 counties in eight Chinese provinces.The results show that participation in the PAR increases the income of both rural and urban resettlers.More specifically,it has a significant positive effect on agricultural and wage income for rural and urban resettlers,respectively.Further analyses show that the income increase for rural resettlers was mainly due to agricultural technology training and that the income increase for town resettlers was attributed to medical security.For the village resettlers,policies should focus on strengthening the development of local industries and training of agricultural technologies.For the urban resettlers,non-agricultural employment and public services in the urban resettlement areas should be promoted.展开更多
An earthquake with Ms5.8 occurred on 10 March 2011 in Yingjiang county, western Yunnan, China. This earthquake caused 25 deaths and over 250 injuries. In order to better understand the seismotectonics in the region, w...An earthquake with Ms5.8 occurred on 10 March 2011 in Yingjiang county, western Yunnan, China. This earthquake caused 25 deaths and over 250 injuries. In order to better understand the seismotectonics in the region, we collected the arrival time data from the Yunnan seismic observational bulletins during 1 January to 25 March 2011, and precisely hand-picked the arrival times from high-quality seismograms that were recorded by the temporary seismic stations deployed by our Institute of Crustal Dynamics, China Earthquake Administration. Using these arrival times, we relocated all the earthquakes including the Yingjiang mainshock and its aftershocks using the double-difference relocation algorithm. Our results show that the relocated earthquakes dominantly occurred along the ENE direction and formed an upside-down bow-shaped structure in depth. It is also observed that after the Yingjiang mainshock, some aftershocks extended toward the SSE over about 10 km. These results may indicate that the Yingjiang mainshock ruptured a conjugate fault system consisting of the ENE trending Da Yingjiang fault and a SSE trending blind fault. Such structural features could contribute to severely seismic hazards during the moderate-size Yingjiang earthquake.展开更多
To reveal the geometry of the seismogenic structure of the Aug. 8, 2017 M_S 7.0 Jiuzhaigou earthquake in northern Sichuan,data from the regional seismic network from the time of the main event to Oct. 31, 2017 were us...To reveal the geometry of the seismogenic structure of the Aug. 8, 2017 M_S 7.0 Jiuzhaigou earthquake in northern Sichuan,data from the regional seismic network from the time of the main event to Oct. 31, 2017 were used to relocate the earthquake sequence by the tomoDD program, and the focal mechanism solutions and centroid depths of the M_L ≥ 3.5 events in the sequence were determined using the CAP waveform inversion method. Further, the segmental tectonic deformation characteristics of the seismogenic faults were analyzed preliminarily by using strain rosettes and areal strains(As). The results indicate:(1) The relocated M_S 7.0 Jiuzhaigou earthquake sequence displays a narrow ～ 38 km long NNW-SSE-trending zone between the NW-striking Tazang Fault and the nearly NSstriking Minjiang Fault, two branches of the East Kunlun Fault Zone. The spatial distribution of the sequence is narrow and deep for the southern segment, and relatively wide and shallow for the northern segment. The initial rupture depth of the mainshock is 12.5 km, the dominant depth range of the aftershock sequence is between 0 and 10 km with an average depth of 6.7 km. The mainshock epicenter is located in the middle of the aftershock region, showing a bilateral rupture behavior. The centroid depths of 32 M_L ≥ 3.5 events range from 3 to 12 km with a mean of about 7.3 km, consistent with the predominant focal depth of the whole sequence.(2) The geometric structure of the seismogenic fault on the southern section of the aftershock area(south of the mainshock) is relatively simple, with overall strike of ～150° and dip angle ～75°, but the dip angle and dip-orientation exhibit some variation along the segment. The seismogenic structure on the northern segment is more complicated; several faults, including the Minjiang Fault, may be responsible for the aftershock activities. The overall strike of this section is ～159° and dip angle is ～59°, illustrating a certain clockwise rotation and a smaller dip angle than the southern segment. The differences between the two segments demonstrate variation of the geometric structure along the seismogenic faults.(3) The focal mechanism solutions of 32 M_L ≥ 3.5 events in the earthquake sequence have obvious segmental characteristics. Strike-slip earthquakes are dominant on the southern segment, while 50% of events on the northern segment are thrusting and oblique thrusting earthquakes, revealing significant differences in the kinematic features of the seismogenic faults between the two segments.(4) The strain rosettes for the mainshock and the entire sequence of 31 M_L ≥ 3.5 aftershocks correspond to strike-slip type with NWW-SEE compressional white lobes and NNE-SSW extensional black lobes of nearly similar size. The strain rosette and As value of the entire sequence of 22 M_L ≥ 3.5 events on the southern segment are the same as those of the M_S 7.0 mainshock,indicating that the tectonic deformation here is strike-slip. However, the strain rosette of the entire sequence of 10 M_L ≥ 3.5 events on the northern segment show prominent white compressional lobes and small black extensional lobes, and the related As value is up to 0.52,indicating that the tectonic deformation of this segment is oblique thrusting with a certain strike-slip component. Differences between the two segments all reveal distinctly obvious segmental characteristics of the tectonic deformation of the seismogenic faults for the Jiuzhaigou earthquake sequence.展开更多
文摘The yangtze River Three Gorges Project is the largest water-conservancy project in the world. After its completion in 2009, its total installed capacity Will be 18.25 million kW With an annual power generation of 84. 7 billion kWh. The total storage capacity will be 39.3 billion cubic meters, and the anti-flood storage capacity Will be 22. 15 billion cubic meters. The project will effectively control flooding along the Y8ngtZe River protect 1.53 million hectares of land, protect the life and property of 15 million people in the middle and lower reaches of the Yangtze River and improve the river’s transportation capacity Many are concerned about the inhabitants in the reservoir area who have to be relocated. According to statistics, over the 17-year construction period, 1.038 million Chongqing people will be relocated, comprising 85 percent of the total number of people who have to be relocated. Such grand scale relocation has rarely been seen in the history of China and the world. To gain a better understanding of the relocation process, staff reporter Wang Xin visited some relocated settlements and interviewed Gan Yuping, vice mayor of Chongqing Municipality and head of the relocation project.
基金financial support from the National Key R&D Program of China (No. 2021YFC3000600)National Natural Science Foundation of China (No. 41872206)National Nonprofit Fundamental Research Grant of China, Institute of Geology, China, Earthquake Administration (No. IGCEA2010)
文摘The three-dimensional(3D)geometry of a fault is a critical control on earthquake nucleation,dynamic rupture,stress triggering,and related seismic hazards.Therefore,a 3D model of an active fault can significantly improve our understanding of seismogenesis and our ability to evaluate seismic hazards.Utilising the SKUA GoCAD software,we constructed detailed seismic fault models for the 2021 M_(S)6.4 Yangbi earthquake in Yunnan,China,using two sets of relocated earthquake catalogs and focal mechanism solutions following a convenient 3D fault modeling workflow.Our analysis revealed a NW-striking main fault with a high-angle SW dip,accompanied by two branch faults.Interpretation of one dataset revealed a single NNW-striking branch fault SW of the main fault,whereas the other dataset indicated four steep NNE-striking segments with a left-echelon pattern.Additionally,a third ENE-striking short fault was identified NE of the main fault.In combination with the spatial distribution of pre-existing faults,our 3D fault models indicate that the Yangbi earthquake reactivated pre-existing NW-and NE-striking fault directions rather than the surface-exposed Weixi-Qiaohou-Weishan Fault zone.The occurrence of the Yangbi earthquake demonstrates that the reactivation of pre-existing faults away from active fault zones,through either cascade or conjugate rupture modes,can cause unexpected moderate-large earthquakes and severe disasters,necessitating attention in regions like southeast Xizang,which have complex fault systems.
基金funded by the National Natural Science Foundation of China(Grant No.42304072)。
文摘On December 18,2023,an M_(s)6.2 earthquake jolted Jishishan County in the Linxia Hui Autonomous Prefecture in Northwest China's Gansu Province,causing substantial casualties and building collapses.The earthquake occurred in the Qilian Block on the northeastern border of the Qinghai-Tibet Plateau,where faults are highly active and the geological structure is complex.In this study,we utilized methods such as relocation,focal mechanism solutions,and earthquake rupture processes to describe seismogenic faults.The results indicated that the majority of aftershocks occurred at a depth of 12 km.The centroid depth of the main shock and the depth of the maximum rupture point during the rupture process were also 12 km.Various geophysical methods exhibited a high degree of consistency in depth exploration.Aftershocks were distributed mainly to the west and north of the main shock and extended in the NNW direction,primarily through unilateral rupture.The main shock was a reverse thrust event with a small dextral strike-slip component.In this study,more regional data,such as previous GPS observations,field geological observations,and the distributions of the primary stress states in the region,were also incorporated.We inferred that the main shock was triggered by the main fault at the northern margin of the Lajishan Fault and that the movement of the main fault also activated some secondary faults.The compressive forces on both sides of the Lajishan Fault Zone led to the uplift of mountain areas,accompanied by some landslides,leading to this catastrophic earthquake event.In this article,the activity relationships among the 2022 M_(s)6.9 Menyuan earthquake,the 2019 M_(s)5.7 Xiahe earthquake,and the Jishishan earthquake under the action of regional stress are also discussed.This study provides additional evidence and new ideas for exploring the seismogenic process of the Lajishan Fault Zone and has implications for future in-depth research on underground activity in this region.
基金supported by the National Natural Science Foundation of China(Grant No.42277152,42041006)the Fundamental Research Funds for the Central Universities,Chang'an University(300102262910)+2 种基金supported by the International Science and Technology Cooperation Program of China(202406560140)Shaanxi Province Science and Technology Innovation Team(Ref.2021TD-51)the innovation team of Shaanxi Provincial Tri-Qin Scholars with Geoscience Big Data and Geohazard Prevention(2022)。
文摘The December 18,2023,M_(S)6.2 Jishishan earthquake occurred along the northeastern margin of the Qinghai-Xizang Plateau within the Laji-Jishi Shan Fault Zone(LJSFZ),a complex thrust-dominated tectonic belt.To identify the seismogenic fault and better understand the regional tectonic framework,we integrated high-resolution Digital Elevation Models(DEMs)derived from GF-7 stereo satellite and Unmanned Aerial Vehicle(UAV)photogrammetry,relocated aftershock sequences,and conducted detailed field investigations.Our results identify four Late Quaternary thrust faults(F1-1 to F1-4),among which the Zhaomuchuan fault(F1-3),a NE-dipping back-thrust,aligns closely with the main-shock and aftershock distribution and exhibits clear Holocene activity.Seismic relocation reveals a NEdipping seismogenic zone at depths of 5-12 km,consistent with a shallow reverse-faulting mechanism under WSW-ENE oblique compression.Structural analysis and cross-sectional profiles suggest that fault F1-3 propagates into a mid-crustal detachment surface,forming a foreland-vergent thrust-nappe system.Importantly,the rupture of this secondary fault,rather than the locked primary boundary fault F1-1,indicates stress transfer and localization within a critically tapered wedge,consistent with global analogs of back-thrust-dominated earthquakes.These findings underscore the seismotectonic complexity of the LJSFZ and highlight the significant seismic hazard posed by subsidiary structures in compressional settings.
文摘The widespread variation of focal depths and fault plane solutions observed in the Hindukush region depicts continuous deformation along the Indian-Eurasian collision zone.For period of twelve years i.e.from 2010 to 2022,a total of 89 intermediate-depth earthquakes of magnitude(Mw)≥5.5 of the Hindukush Region were considered,relocated using both regional and tele seismic data with 90 per cent confidence limits of less than 20 km.Two distinct seismic activity clusters:First one at a deeper depth and second at a shallower depth having different P-axes were observed that verifies the internal structure and geometry of Hindukush zone as suggested in previous studies.Beneath the Hindukush collision zone,there exists a complex pattern of deformation,arising from a combination of compression,tension,shearing and necking states due to an unusual and a rare case of subduction that is not from oceanic plate.The Hindukush seismic zone extends from 70 to 300 km depth and mostly strikes east-west and then turns northeast.The relocated seismicity by merging data of seismic network close to Hindukush along with international data shows that the Hindukush zone may be divided vertically into upper and lower slabs separated by a gap at about 150 km depth at which strike and dip directions change sharply with significant structural changes.Seismicity rate is higher in the lower part of Hindukush,having large magnitude events in a small volume below 180 km forming complex pattern of source mechanisms.Contrary in upper part seismicity rate is lower and scattered.The Global CMT(Global Centroid-Moment-Tensor Project)source mechanisms of intermediate depth earthquakes have a systematic pattern of reverse faulting with the vertical T-axes,while shallow events do not have such pattern.The vertical T-axes of the intermediate-depth events may be attributed to negative buoyancy caused by subduction of the cold and denser slab.
文摘As a crucial pivot for national strategic development,the university relocation project in Xiong’an New Area undertakes the mission of optimizing capital functions and promoting regional coordinated development.Taking the Xi-ong’an Campus of China University of Geosciences(Beijing)as a case study,this paper explores the collaborative pa-thways between universities and cities in terms of functional complementarity,resource sharing,and ecological symbiosis from the perspective of campus functional layout and spatial optimization.By integrating four core concepts—green ecology,intelligent technology,cultural inheritance,and traffic optimization—it proposes a design strategy of“breaking boundaries and multi-dimensional linkage,”aiming to construct a new spatial paradigm of urban-university integration and provide theoretical support and practical references for the development of higher education and urbanization in Xiong’an New Area.
基金supported by Fundamental Research Funds from the Institute of Geophysics,China Earthquake Administration(Nos.DQJB22B26 and DQJB22B19)the National Key Research and Development Program of China(No.2020YFA0710603-02).
文摘The epicenter of the Luxian M_(S)6.0 earthquake on September 16,2021,was located in the southern Sichuan Basin,which is a historically seismically quiescent area.In recent years,the frequency of earthquakes has increased with the large-scale exploitation of shale gas.No evident surface fractures or seismic faults were observed after the Luxian earthquake.Based on high-quality data recorded by a dense seismic array composed of 70 portable stations with an average spacing of 2-3 km,a highresolution seismic catalog was constructed for 7 days before and 36 days after the M_(S)6.0 earthquake using LOC-FLOW,an effective workflow of phase picking,phase association,and earthquake location.Based on the new earthquake catalog,four earthquake clusters that occurred within the Yujiasi Syncline during this period were identified.Among them,the M_(S)6.0 main earthquake sequence had a NW-SE trend and inclined towards the SW,with a length of approximately 8 km and width of 5 km.The M_(S)6.0 earthquake sequence only appeared after the mainshock.The other three clusters were located in the northeast direction of the M_(S)6.0 earthquake sequence,all of which were NE-SW trending strips and had no evident direct correlation with the M_(S)6.0 mainshock.The focal depth was concentrated in the range of 2-7 km.Based on the seismic sequence profile and structural background,the M_(S)6.0 seismic structure may be a blind buried fault zone with a NW strike composed of multiple small conjugate faults with NE and SW dip.The fault was not exposed on the surface and was related to the detachment structure in the deep part of the Sichuan Basin.
文摘Stepping into Donglong Group’s intelligent factory in the Yangtze River Delta,the automated production lines is transforming fluffy down into premium home textiles export to Europe and America.At a pivotal moment of global supply chain restructuring,this homegrown textile and apparel exporter is answering a critical question:How can Chinese textile companies sustain their competitive edge amid tariff barriers and supply chain relocation?
基金Projects(11472311,41272304,51504288)supported by the National Natural Science Foundation of China
文摘A new method, named relocation, was proposed to reduce the impact of sensor errors systematically, especially whenavailable data of sensors are abundant. The procedure includes evaluating the reliability of every sensors datum, processing the initiallocation by the credible data, and selecting a set of equations with optimal noise tolerance according to the relative relationshipbetween the initial location and sensors location, then calculating the final location by k-mean voting. The results obtained in thisresearch include comparing traditional location method with the presented method in both simulation and field experiment. In thefield experiment, the location error of relocation method reduced 41.8% compared with traditional location method. The resultssuggested that relocation method can improve the fault-tolerant performance significantly.
基金Supported by Talent-Introduction Scientific Research Program of Yancheng Institute of Technology(XKR2011078)~~
文摘By investigating present relocation residential districts for peasants whose houses are removed for the unified planning of rural areas in north Jiangsu Province, as well as residents' feelings about the environment of residential district, main architectural structures and energy consumption conditions, the indoor thermal environment, use of main heating and cooling facilities, residents' satisfaction on the acoustical and luminous environment, major space-enclosing structures and calculation of energy-saving designs are analyzed, and suggestions are given for the architectural design of relocation residential districts in the study area. It is stressed that the relationship between energy conservation and architectural layout, orientation, lighting, ventilation, selection of enclosing-structure materials, facade, color and style should be properly handled in the planning, and the focus is to control building orientation and shape coefficient, on the basis of which energy-saving designs of windows, exterior walls and roofs can be done. Energy consumption of present residential buildings is calculated and analyzed to bring forth new ideas to the energy-saving designs for relocation residential districts in north Jiangsu Province, and establish an architectural energy-saving system suitable for climatic and natural conditions of north Jiangsu to instruct the energy-saving designs of relocation residential districts in the study area.
基金supported by a grant from the National Earthquake Predicting Field in Sichuan and Yunnan(No.2016CESE0204).
文摘Locating an earthquakes focal depth is always a key project in seismology. Precise focal depth is of critical importance for evaluating seismic hazards, deciphering dynamic mechanisms of earthquake generating,estimating aftershock evolutions and risk,as well as monitoring nuclear tests. However,how we determine an accurate focal depth is always a challenge in seismological studies. Aiming to solve these problems, we analyzed and summarized the present status and the future development of earthquake focal depth locating. In this paper we first reviewed the present status of focal depth locating in the world,and summarized the frequently-used relocating methods and ideas at present,and introduced two types of focal depth relocating ideas: arrival time relocating and waveform modeling methods. For these ideas,we systematically described the S-P and the Pn-Pg methods that belong to arrival time method,and polarization focal depth locating and amplitude focal depth locating that belongs to waveform modeling,and further analyzed the advantages and limitations of these methods. Since the depth phase methods are highly sensitive to focal depth,and are relatively free from the uncertainties of crustal models,we mainly reviewed the depth phases of s Pm P,s PL,s Pn,and s Sn,and quantitatively evaluated their availabilities and characteristics. Second,we also discussed the effects of crustal velocity models on the reliability of focal depth locating,and reviewed the advancements of seismic tomography techniques over recent years. Finally,based on the present status of the progress on the focal depth locating,and studies of seismic velocity structures,we proposed an idea of combining multiple datasets and relocating methods,jointly utilizing seismologic and geodetic techniques to relocate focal depth,which should be the major research field in investigating focal depth and source parameters in the near future.
文摘Based on the construction property of rolled compacted concrete, three-dimensional finite element relocating mesh method was developed in simulating construction process and computing temperature and stress field. Using this method, the temperature and the thermal stress fields developed in the RCC gravity dam of the Longtan project with or without a longitudinal joint during construction and operation are calculated so as to simulate the construction process. The computation results show that the value of the thermal stresses developed in the dam even, without any longitudinal joint, could meet the design criteria provided the placement temperature is adequately controlled.
文摘According to the construction characteristic of RCC dam cast by layers, three-dimensional finite element relocating mesh method is developed to simulate construction process and compute temperature field. The computation model of relocating mesh method is expatiated in detail; based on the thermodynamic properties of RCC materials, the feasibility and error of relocating mesh method are analyzed and demonstrated; The computation results in this article are verified by means of the temperature observation data of certain RCC gravity dam. The results show that the temperature field computed by three-dimensional finite element relocating mesh method can not only ensure the computation precision, but also improve the calculation efficiency greatly. This provides an effective method for simulating construction process and computing temperature field of RCC dam.
文摘In this paper, regarding the actual conditions of a roller compacted concrete dam, three-dimensional finite element relocating mesh method is utilized to simulate and calculate the temperature field of the RCC dam during the construction stage and operating period. The calculation is well consistent with the actual construction process, the thin-layer pouring process the pouring temperature and all kinds of external loads involved being taken into account, By comparing and analyzing of the impact of the cold wave on the dam stress, important references are provided for the RCCD design and the temperature control during construction.
基金supported by the National Natural Science Foundation of China(71861147002 and 71761147004)supported by the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(20XHN086)。
文摘This paper analyses the impact of the poverty alleviation relocation(PAR)program on rural household income and evaluates the heterogeneous income effects of various relocation modes,based on a panel dataset of relocated households from 16 counties in eight Chinese provinces.The results show that participation in the PAR increases the income of both rural and urban resettlers.More specifically,it has a significant positive effect on agricultural and wage income for rural and urban resettlers,respectively.Further analyses show that the income increase for rural resettlers was mainly due to agricultural technology training and that the income increase for town resettlers was attributed to medical security.For the village resettlers,policies should focus on strengthening the development of local industries and training of agricultural technologies.For the urban resettlers,non-agricultural employment and public services in the urban resettlement areas should be promoted.
基金supported by National Natural Science Foundation of China(Nos.40974201 and 40774044)to J.Lei
文摘An earthquake with Ms5.8 occurred on 10 March 2011 in Yingjiang county, western Yunnan, China. This earthquake caused 25 deaths and over 250 injuries. In order to better understand the seismotectonics in the region, we collected the arrival time data from the Yunnan seismic observational bulletins during 1 January to 25 March 2011, and precisely hand-picked the arrival times from high-quality seismograms that were recorded by the temporary seismic stations deployed by our Institute of Crustal Dynamics, China Earthquake Administration. Using these arrival times, we relocated all the earthquakes including the Yingjiang mainshock and its aftershocks using the double-difference relocation algorithm. Our results show that the relocated earthquakes dominantly occurred along the ENE direction and formed an upside-down bow-shaped structure in depth. It is also observed that after the Yingjiang mainshock, some aftershocks extended toward the SSE over about 10 km. These results may indicate that the Yingjiang mainshock ruptured a conjugate fault system consisting of the ENE trending Da Yingjiang fault and a SSE trending blind fault. Such structural features could contribute to severely seismic hazards during the moderate-size Yingjiang earthquake.
基金supported by National Science Foundation of China(41574047)National Key R&D Program of China(2018YFC150330501)
文摘To reveal the geometry of the seismogenic structure of the Aug. 8, 2017 M_S 7.0 Jiuzhaigou earthquake in northern Sichuan,data from the regional seismic network from the time of the main event to Oct. 31, 2017 were used to relocate the earthquake sequence by the tomoDD program, and the focal mechanism solutions and centroid depths of the M_L ≥ 3.5 events in the sequence were determined using the CAP waveform inversion method. Further, the segmental tectonic deformation characteristics of the seismogenic faults were analyzed preliminarily by using strain rosettes and areal strains(As). The results indicate:(1) The relocated M_S 7.0 Jiuzhaigou earthquake sequence displays a narrow ～ 38 km long NNW-SSE-trending zone between the NW-striking Tazang Fault and the nearly NSstriking Minjiang Fault, two branches of the East Kunlun Fault Zone. The spatial distribution of the sequence is narrow and deep for the southern segment, and relatively wide and shallow for the northern segment. The initial rupture depth of the mainshock is 12.5 km, the dominant depth range of the aftershock sequence is between 0 and 10 km with an average depth of 6.7 km. The mainshock epicenter is located in the middle of the aftershock region, showing a bilateral rupture behavior. The centroid depths of 32 M_L ≥ 3.5 events range from 3 to 12 km with a mean of about 7.3 km, consistent with the predominant focal depth of the whole sequence.(2) The geometric structure of the seismogenic fault on the southern section of the aftershock area(south of the mainshock) is relatively simple, with overall strike of ～150° and dip angle ～75°, but the dip angle and dip-orientation exhibit some variation along the segment. The seismogenic structure on the northern segment is more complicated; several faults, including the Minjiang Fault, may be responsible for the aftershock activities. The overall strike of this section is ～159° and dip angle is ～59°, illustrating a certain clockwise rotation and a smaller dip angle than the southern segment. The differences between the two segments demonstrate variation of the geometric structure along the seismogenic faults.(3) The focal mechanism solutions of 32 M_L ≥ 3.5 events in the earthquake sequence have obvious segmental characteristics. Strike-slip earthquakes are dominant on the southern segment, while 50% of events on the northern segment are thrusting and oblique thrusting earthquakes, revealing significant differences in the kinematic features of the seismogenic faults between the two segments.(4) The strain rosettes for the mainshock and the entire sequence of 31 M_L ≥ 3.5 aftershocks correspond to strike-slip type with NWW-SEE compressional white lobes and NNE-SSW extensional black lobes of nearly similar size. The strain rosette and As value of the entire sequence of 22 M_L ≥ 3.5 events on the southern segment are the same as those of the M_S 7.0 mainshock,indicating that the tectonic deformation here is strike-slip. However, the strain rosette of the entire sequence of 10 M_L ≥ 3.5 events on the northern segment show prominent white compressional lobes and small black extensional lobes, and the related As value is up to 0.52,indicating that the tectonic deformation of this segment is oblique thrusting with a certain strike-slip component. Differences between the two segments all reveal distinctly obvious segmental characteristics of the tectonic deformation of the seismogenic faults for the Jiuzhaigou earthquake sequence.
