Hydraulic fracturing(HF)has achieved significant commercial success in unconventional oil and gas development.However,it has the potential to induce fault slip.This study investigates the physical mechanisms underlyin...Hydraulic fracturing(HF)has achieved significant commercial success in unconventional oil and gas development.However,it has the potential to induce fault slip.This study investigates the physical mechanisms underlying potential fault slip triggered by HF operations under varying geological and operational constraints.First,we elucidate the relationship between the critical stress state and the elastic modulus of the fault,and refine a formula for the maximum crustal stress difference on critically stressed faults,including stress concentration,friction,and dip.Second,we compare the role of injected fluid in permeable faults with that in impermeable faults,and demonstrate that fault slips can be triggered by a combination of friction decrease and pore pressure increase,even after ceasing injection.Specifically,we reveal that friction decline dominates induced fault slip on high permeable and hydraulically connected fault.Third,based on experimental results and theoretical analysis,we quantify the influence region of stress transfer under different conditions of well location and injection pressure.The results reveal that the elastic modulus of the fault controls the stress concentration on the fault plane.The dip of the fault and the stress concentration jointly determine the maximum crustal stress difference required for failure in critically stressed reverse faults.Thus,our study is more accurate in estimating the proximity of the in-situ stress to the critical state,compared with traditional methods.For critical reverse faults,the risk of induced slip is positively correlated with both injection pressure and friction of fault plane.When the injection pressure(PI)is 100 MPa and the friction(μ)is 0.8,the safe distance from injection point to critically stressed faults along the direction of maximum principal stress and maximum principal stress(dH and dv)should exceed 25 and 18 times as the hydraulic fracture halflength.When PI is 100 MPa andμis 0.6,dH and dv are 23 and 17 times as the hydraulic fracture halflength,respectively.When PI is 60 MPa andμis 0.6,dH and dv are 18 and 13 times as the hydraulic fracture half-length,respectively.The works enhance our understanding of HF-induced fault slip and potentially guide designs of the shale gas well location and trajectory for safer production.展开更多
An approach for estimating ground surface rupture caused by strong earthquakes is presented in this paper, where the finite element （FE） method of continuous and discontinuous coalescent displacement fields is adopt...An approach for estimating ground surface rupture caused by strong earthquakes is presented in this paper, where the finite element （FE） method of continuous and discontinuous coalescent displacement fields is adopted. The onset condition of strain localization is introduced to detect the formation of the slippage line. In the analysis, the Drucker-Prager constitutive model is used for soils and the rate- and state-dependent friction law is used on the slippage line to simulate the evolution of the sliding. A simple application to evaluate the ground surface rupture induced by a reverse fault movement is provided, and the numerical simulation shows good agreement with failure characteristics observed in the field after strong earthquakes.展开更多
Severe faults have caused many earthquakes around the world throughout history.More recently,earthquakes have occurred in Taiwan,China(Chi-Chi fault),and elsewhere,causing loss of lives and destroying many buildings a...Severe faults have caused many earthquakes around the world throughout history.More recently,earthquakes have occurred in Taiwan,China(Chi-Chi fault),and elsewhere,causing loss of lives and destroying many buildings and structures.These tectonic movements have gained attention from engineers,and in the past 15 years,the focus has been on faulting mechanisms.In this study,a physical model(1 g)was fabricated and used to evaluate the impact of a reverse fault in a field with a tunnel.In the 1 g model,researchers installed additional gauges on the tunnel,so that all the displacements could be adjusted,and all the responses could be monitored during faulting.An experimental study of various soil properties(cohesion and friction angles)in reverse faults on the tunnel lining were carried out and are described herein.A comparison of results for different levels of soil cohesion revealed that it can dramatically reduce the displacement by as much as 40%,and that friction angles of 27ºcan record approximately 60%more displacements than at 37º.Furthermore,a comparison of fault angles of 30ºand 60ºindicates that the displacements can be different by more than 43%in cohesionless soil and about 64%for a friction angle of 27º.展开更多
Urban tunnels crossing faults are always at the risk of severe damages.In this paper,the efects of a reverse and a normal fault movement on a transversely crossing shallow shotcreted tunnel are investigated by 3D fini...Urban tunnels crossing faults are always at the risk of severe damages.In this paper,the efects of a reverse and a normal fault movement on a transversely crossing shallow shotcreted tunnel are investigated by 3D finite difference analysis.After verifying the accuracy of the numerical simulation predictions with the centrifuge physical model results,a parametric study is then conducted.That is,theleffects of various parameters such as the sprayed concrete thickness,the geo-mechanical properties of soil,the tunnel depth,and the fault plane dip angle are studied on the displacements of the ground surface and the tunnel structure,and on the plastic strains of the soil mass around tunnel.The results of each case of reverse and normal faulting are independently discussed and then compared with each other.It is obtained that deeper tunnels show greater displacements for both types of faulting.展开更多
Tunnels extend in large stretches with continuous lengths of up to hundreds of kilometers which are vulnerable to faulting in earthquake-prone areas.Assessing the interaction of soil and tunnel at an intersection with...Tunnels extend in large stretches with continuous lengths of up to hundreds of kilometers which are vulnerable to faulting in earthquake-prone areas.Assessing the interaction of soil and tunnel at an intersection with an active fault during an earthquake can be a beneficial guideline for tunnel design engineers.Here,a series of 4 centrifuge tests are planned and tested on continuous tunnels.Dip-slip suface faulting in reverse mechanism of 60°is modeled by a fault simulator box in a quasi-static manner.Failure mechanism,progression and locations of damages to the tunnels are assessed through a gradual increase in Permanent Ground Displacement(PGD).The ground surface deformations and strains,fault surface trace,fault scarp and the sinkhole caused by fault movement are observed here.These ground surface deformations are major threats to stability,safety and serviceability of the structures.According to the observations,the modeled tunnels are vulnerable to reverse fault rupture and but the functionality loss is not abrupt,and the tunnel will be able to tolerate some fault displacements.By monitoring the progress of damage states by increasing PGD,the fragility curves corresponding to each damage state were plotted and interpreted in related figures.展开更多
Fault-related parameters are critical for studying tectonic evolution, deformation character- istics, active tectonism, and seismic hazards. A new method of calculating reverse-fault- related parameters has been devel...Fault-related parameters are critical for studying tectonic evolution, deformation character- istics, active tectonism, and seismic hazards. A new method of calculating reverse-fault- related parameters has been developed, which uses systematic analysis of the geometrical characteristics of normal and reverse scarps of reverse faults together with measurements of topographic profiles and fault bedding. The results show that the most suitable method of calculating fault parameters heavily relies on the specific type of fault scarp. For a reverse scarp, the size of the vertical displacement （VD） of the fault, the vertical separation （VS） of the hanging wall and the footwall, and the fault scarp height （SH）how the relationship VD ≥VS ≥ SH; conversely, for normal scarps, VD ≤ VS ≤ SH. The theoretical equations were used to study fault deformation in the Southwest Tianshan Mountain foreland basin. The results showed that, for every fault, VD ≥ VS ≥SH, which is consistent with our predicted relationship. This finding demonstrates that this method is suitable to explore structural information of reverse faults. In the study area, the vertical displacement is 1.4 times the horizontal displacement, suggesting that fiexural-slip faults may play an important role in transferring local deformation from horizontal shortening to vertical uplift. Therefore, one of the most important steps in correct calculation of reverse-fault-related parameters is selection of the proper equations by identifying the specific type of fault scarp and the corresponding calculation method.展开更多
The Anninghe fault is one of the significant earthquake-generating fault zones in the Southwest China. Local historical record shows that a M2≥7 strong earthquake occurred in the year of 1536. On the basis of the det...The Anninghe fault is one of the significant earthquake-generating fault zones in the Southwest China. Local historical record shows that a M2≥7 strong earthquake occurred in the year of 1536. On the basis of the detailed air-photographic interpretation and field investigation, we have acquired the following knowledge： ① The average sinistral strike-slip rate since the Late Pleistocene is about 3～7 mm/a; ② There is important reverse faulting along the fault zone besides the main left-lateral strike-slip motion, and the shortening rate across the Anninghe fault zone due to the reverse faulting is about 1.7-4.0 mm/a. If the Xianshuihe fault zone is simply partitioned into the Anninghe and Daliangshan faults, we can also get a slip rate of 3-7 mm/a along the Daliangshan fault zone, which is the same as that on the Anninghe fault zone. Moreover, on the basis of our field investigation and the latest knowledge concerning the active tectonics of Tibetan crust, we create a dynamic model for the Anninghe fault zone.展开更多
The role of authigenic clay growth in clay gouge is increasingly recognized as a key to understanding the mechanics of berittle faulting and fault zone processes,including creep and seismogenesis,and providing new ins...The role of authigenic clay growth in clay gouge is increasingly recognized as a key to understanding the mechanics of berittle faulting and fault zone processes,including creep and seismogenesis,and providing new insights into the ongoing debate about the frictional strength of brittle fault(Haines and van der Pluijm,2012).However,neither the conditions nor the processes which展开更多
Software fault positioning is one of the most effective activities in program debugging. In this paper, we propose a model-based fault positioning method to detect the faults of embedded program without source code. T...Software fault positioning is one of the most effective activities in program debugging. In this paper, we propose a model-based fault positioning method to detect the faults of embedded program without source code. The system takes the machine code of embedded software as input and translates the code into high-level language C with the software reverse engineering program. Then, the static analysis on the high-level program is taken to obtain a control flow graph（CFG）, which is denoted as a node-tree and each node is a basic block. According to the faults found by the field testing, we construct a fault model by extracting the features of the faulty code obtained by ranking the Ochiai coefficient of basic blocks. The model can be effectively used to locate the faults of the embedded program. Our method is evaluated on ST chips of the smart meter with the corresponding source code. The experiment shows that the proposed method has an effectiveness about 87% on the fault detection.展开更多
The MohroCoulomb criterion has been widely used to explain formation of fractures. However, it fails to explain large strain deformation that widely occurs in nature. There is presently a new theory, the MEMC, which i...The MohroCoulomb criterion has been widely used to explain formation of fractures. However, it fails to explain large strain deformation that widely occurs in nature. There is presently a new theory, the MEMC, which is mathematically expressed as Meff = （（σ1-σ3） L.sin 2α sin α）/2, where σ1-σ3 represents the yield strength of the related rock, L is a unit length and a is the angle between σ1 and deformation bands. This criterion demonstrates that the maximum value appears at angles of ±54.7° to σ1 and there is a slight difference in the moment in the range of 55°±10°. The range covers the whole observations available from nature and experiments. Its major implications include： （1） it can be used to determine the stress state when the related deformation features formed; （2） it provides a new approach to determine the Wk of the related ductile shear zone if only the ratio of the vorticity and strain rate remains fixed; （3） It can be used to explain （a） the obtuse angle in the contraction direction of conjugate kink-bands and extensional crenulation cleavages, （b） formation of low-angle normal faults and high-angle reverse faults, （c） lozenge ductile shear zones in basement terranes, （d） some crocodile structures in seismic profiles and （e） detachment folds in foreland basins.展开更多
Based on a large amount of seismic, drilling and core data, the characteristics of the early- middle Miocene submarine fans in the Baiyun Sag, northern South China Sea are investigated. By analyzing the sedimentary pr...Based on a large amount of seismic, drilling and core data, the characteristics of the early- middle Miocene submarine fans in the Baiyun Sag, northern South China Sea are investigated. By analyzing the sedimentary processes of submarine fans in SQ21 （SQ21 refers to the 3rd-order sequence with its bottom boundary 21 Ma）, a sedimentary model of the sand-rich fans is established and the main factors controlling fan deposition are detailed. The results indicate that from early to middle Miocene the Pearl River Mouth Basin developed seven 3rd-order sequences in all, with each lowstand systems tract （LST） of the sequence corresponding to submarine fans. However, only the fans in SQ13.8 and SQ21 are sand-rich fans, the others being mud-rich fans. The cores reveal that the submarine fans in the Pearl River Mouth Basin developed five lithofacies： （1） mud clast-bearing sandstone, interpreted as channel deposits; （2） typical turbidite sandstones, also interpreted as channel deposits; （3） thin-bedded sandstone and mudstone, interpreted as channel-levee complex deposits; （4） massive sandstones, interpreted as lobe deposits; （5） massive mudstone, interpreted as hemipelagic mud. The sand-rich submarine fans in the Pearl River Mouth Basin mainly developed in LST, and in LST reverse faults were active, which led to the formation of accommodation on the shelf. Different from the theory of classic sequence stratigraphy, the accommodation on the shelf captures terrigenous debris transported by the Pearl River, and the uplift at the edge of shelf serves as a ＂Linear Source＂ for the deep water area instead of the Pearl River. Therefore, the fans mainly derived from the eroded debris from the uplift. Factors controlling fan deposition include the basin＇s tectonic framework, the evolution of the slope break, relative sea-level changes as well as the evolution of the fault system, and the fans are formed under the combination of the above factors.展开更多
On January 1, 2024 at 16:10:09 JST, an M_(j) 7.6 earthquake struck the Noto Peninsula in the southern part of the Sea of Japan. This location has been experiencing an earthquake swarm for more than three years. Here, ...On January 1, 2024 at 16:10:09 JST, an M_(j) 7.6 earthquake struck the Noto Peninsula in the southern part of the Sea of Japan. This location has been experiencing an earthquake swarm for more than three years. Here, we provide an overview of this earthquake, focusing on the slip distribution of the mainshock and its relationship with the preceding swarm. We also reexamined the source areas of other large earthquakes that occurred around the Sea of Japan in the past and compared them with the Matsushiro earthquake swarm in central Japan from1964 to 1968. The difference between the Matsushiro earthquake swarm and the Noto earthquake swarm is the surrounding stress field. The Matsushiro earthquake swarm was a strike-slip stress field, so the cracks in the crust were oriented vertically. This allowed fluids seeped from the depths to rise and flow out to the surface. On the other hand, the Noto area was a reverse fault stress field. Therefore, the cracks in the earth's crust were oriented horizontally. Fluids flowing underground in deep areas could not rise and spread over a wide area in the horizontal plane. This may have caused a large amount of fluid to accumulate underground, triggering a large earthquake. Although our proposed mechanism does not take into account other complex geological conditions into consideration, it may provide a simple way to explain why the Noto swarm is followed by a large earthquake while other swarms are not.展开更多
Buried hill is an important exploration field in Dawangzhuang block. Because Dawangzhuang buried hill has experienced multi-stage tectonic movement, the complexity of tectonic movement determines the diversity of buri...Buried hill is an important exploration field in Dawangzhuang block. Because Dawangzhuang buried hill has experienced multi-stage tectonic movement, the complexity of tectonic movement determines the diversity of buried hill morphology, and the diversity of buried hill structural morphology determines its reservoir forming characteristics. Therefore, the research on the structural style and reservoir forming characteristics of Dawangzhuang buried hill is of great significance in the process of oil and gas exploration at this stage. This paper summarizes the structural style of Dawangzhuang buried hill. On this basis, 67 small fault blocks divided in the study area are classified and counted. Further, according to the seismic profile and logging data, the well data and reservoir profile of characteristic wells are counted and compared, and the reservoir forming characteristics and main controlling factors of Dawangzhuang buried hill are found. The above understanding has certain guiding significance for the further exploration of Dawangzhuang buried hill.展开更多
3D geological modeling is an inevitable choice for coal exploration to adapt to the transformation of coal mining for green, fine, transparent and Intelligent mining. In the traditional Coalfield exploration geologica...3D geological modeling is an inevitable choice for coal exploration to adapt to the transformation of coal mining for green, fine, transparent and Intelligent mining. In the traditional Coalfield exploration geological reports, the spatial expression form for the coal seams and their surrounding rocks are 2D maps. These 2D maps are excellent data sources for constructing 3D geological models of coal field exploration areas. How to construct 3D models from these 2D maps has been studying in coal exploration industry for a long time, and still no breakthrough has been achieved so far. This paper discusses the principle, method and software design idea of constructing 3D geological model of an exploration area with 2D maps made by AutoCAD/MapGIS. At first, the paper analyzes 3D geological surface expression mode in 3D geological modeling software. It is pointed out that although contour method has unique advantages in coal field exploration, TIN (Triangular Irregular Network) is still the standard configuration of 3D modeling software for coal field. Then, the paper discusses the method of 2D line features obtaining elevation and upgrading 2D curve to 3D curve. Next, the method of semi-automatic partition is introduced to build the boundary ring of the surface patch, that is, the user clicks and selects the line feature to build the outer boundary ring of the surface patch. Then, Auto-process method for fault line inside of the outer boundary ring is discussed, it including construction of fault ring, determining fault ring being normal fault ring or reverse fault ring and an algorithm of dealing with normal fault ring. An algorithm of dealing with reverse fault ring is discussed detailly, the method of expanding reverse fault ring and dividing the duplicate area in reverse fault into two portions is introduced. The paper also discusses the method of extraction ridge line/valley line, the construction of fault plane, the construction of stratum and coal body. The above ideas and methods have been initially implemented in the “3D modeling platform for coal field exploration” software, and applied to the 3D modeling practice of data from several coal field exploration areas in Ningxia, Shanxi, Qinghai, etc.展开更多
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
The Cenozoic structural architecture and geodynamic mechanism of the Longmen Shan structural belt are essential for understanding the tectonic evolution of the eastern Tibetan Plateau,but remain controversial.Models o...The Cenozoic structural architecture and geodynamic mechanism of the Longmen Shan structural belt are essential for understanding the tectonic evolution of the eastern Tibetan Plateau,but remain controversial.Models of different manners of deformation in different lithospheric levels have been proposed.For example,the crustal extrusion model suggests that Late Cenozoic deformation of the Longmen Shan was dominated by crustal shortening,whereas the channel flow model proposes lower crustal thickening and flow,accommodated by frontal shortening and hinterland extension.This study compiles previously published low-temperature thermochronology data from the Longmen Shan to constrain spatial changes in rock exhumation and test previous geodynamic models.The results show that exhumation increases abruptly across the Yingxiu-Beichuan fault,suggesting the fault is the main thrust boundary between the Longmen Shan and the Sichuan Basin to the east.Further,younger Late Cenozoic cooling ages and faster exhumation are observed on the hinterland Wenchuan-Maowen fault,where a dichotomy of ages on the hanging wall versus footwall suggests Late Cenozoic thrust activity.In addition,towards the hinterland to the west,exhumation rates decrease threefold over a distance of about 80 km.Such an exhumation pattern indicates a westward decrease of tectonic uplift,providing the regional topography reached a steady-state,whereby exhumation is in balance with tectonic uplift.The observed spatial changes in exhumation support a listric crustal configuration where reverse faults in the Longmen Shan merge gradually into a gentle detachment seated at depth.Results of this study support a revised upper crustal shortening model,where the triangular Songpan-Ganzi terrane,bounded by two left-lateral strike-slip faults(Ganzi-Xianshuihe fault to the south and eastern Kunlun fault to the north),might have extruded eastward towards the western margin of the Sichuan Basin along the listric Longmen Shan faults.展开更多
基金supported by the National Natural Science Foundation of China(No.:52274175)。
文摘Hydraulic fracturing(HF)has achieved significant commercial success in unconventional oil and gas development.However,it has the potential to induce fault slip.This study investigates the physical mechanisms underlying potential fault slip triggered by HF operations under varying geological and operational constraints.First,we elucidate the relationship between the critical stress state and the elastic modulus of the fault,and refine a formula for the maximum crustal stress difference on critically stressed faults,including stress concentration,friction,and dip.Second,we compare the role of injected fluid in permeable faults with that in impermeable faults,and demonstrate that fault slips can be triggered by a combination of friction decrease and pore pressure increase,even after ceasing injection.Specifically,we reveal that friction decline dominates induced fault slip on high permeable and hydraulically connected fault.Third,based on experimental results and theoretical analysis,we quantify the influence region of stress transfer under different conditions of well location and injection pressure.The results reveal that the elastic modulus of the fault controls the stress concentration on the fault plane.The dip of the fault and the stress concentration jointly determine the maximum crustal stress difference required for failure in critically stressed reverse faults.Thus,our study is more accurate in estimating the proximity of the in-situ stress to the critical state,compared with traditional methods.For critical reverse faults,the risk of induced slip is positively correlated with both injection pressure and friction of fault plane.When the injection pressure(PI)is 100 MPa and the friction(μ)is 0.8,the safe distance from injection point to critically stressed faults along the direction of maximum principal stress and maximum principal stress(dH and dv)should exceed 25 and 18 times as the hydraulic fracture halflength.When PI is 100 MPa andμis 0.6,dH and dv are 23 and 17 times as the hydraulic fracture halflength,respectively.When PI is 60 MPa andμis 0.6,dH and dv are 18 and 13 times as the hydraulic fracture half-length,respectively.The works enhance our understanding of HF-induced fault slip and potentially guide designs of the shale gas well location and trajectory for safer production.
基金National Science Foundation Council State KeyLaboratory of Frozen Soil Engineering (SKLFSE200504)State Commonweal Research Project (2002DIB30076)
文摘An approach for estimating ground surface rupture caused by strong earthquakes is presented in this paper, where the finite element （FE） method of continuous and discontinuous coalescent displacement fields is adopted. The onset condition of strain localization is introduced to detect the formation of the slippage line. In the analysis, the Drucker-Prager constitutive model is used for soils and the rate- and state-dependent friction law is used on the slippage line to simulate the evolution of the sliding. A simple application to evaluate the ground surface rupture induced by a reverse fault movement is provided, and the numerical simulation shows good agreement with failure characteristics observed in the field after strong earthquakes.
文摘Severe faults have caused many earthquakes around the world throughout history.More recently,earthquakes have occurred in Taiwan,China(Chi-Chi fault),and elsewhere,causing loss of lives and destroying many buildings and structures.These tectonic movements have gained attention from engineers,and in the past 15 years,the focus has been on faulting mechanisms.In this study,a physical model(1 g)was fabricated and used to evaluate the impact of a reverse fault in a field with a tunnel.In the 1 g model,researchers installed additional gauges on the tunnel,so that all the displacements could be adjusted,and all the responses could be monitored during faulting.An experimental study of various soil properties(cohesion and friction angles)in reverse faults on the tunnel lining were carried out and are described herein.A comparison of results for different levels of soil cohesion revealed that it can dramatically reduce the displacement by as much as 40%,and that friction angles of 27ºcan record approximately 60%more displacements than at 37º.Furthermore,a comparison of fault angles of 30ºand 60ºindicates that the displacements can be different by more than 43%in cohesionless soil and about 64%for a friction angle of 27º.
文摘Urban tunnels crossing faults are always at the risk of severe damages.In this paper,the efects of a reverse and a normal fault movement on a transversely crossing shallow shotcreted tunnel are investigated by 3D finite difference analysis.After verifying the accuracy of the numerical simulation predictions with the centrifuge physical model results,a parametric study is then conducted.That is,theleffects of various parameters such as the sprayed concrete thickness,the geo-mechanical properties of soil,the tunnel depth,and the fault plane dip angle are studied on the displacements of the ground surface and the tunnel structure,and on the plastic strains of the soil mass around tunnel.The results of each case of reverse and normal faulting are independently discussed and then compared with each other.It is obtained that deeper tunnels show greater displacements for both types of faulting.
文摘Tunnels extend in large stretches with continuous lengths of up to hundreds of kilometers which are vulnerable to faulting in earthquake-prone areas.Assessing the interaction of soil and tunnel at an intersection with an active fault during an earthquake can be a beneficial guideline for tunnel design engineers.Here,a series of 4 centrifuge tests are planned and tested on continuous tunnels.Dip-slip suface faulting in reverse mechanism of 60°is modeled by a fault simulator box in a quasi-static manner.Failure mechanism,progression and locations of damages to the tunnels are assessed through a gradual increase in Permanent Ground Displacement(PGD).The ground surface deformations and strains,fault surface trace,fault scarp and the sinkhole caused by fault movement are observed here.These ground surface deformations are major threats to stability,safety and serviceability of the structures.According to the observations,the modeled tunnels are vulnerable to reverse fault rupture and but the functionality loss is not abrupt,and the tunnel will be able to tolerate some fault displacements.By monitoring the progress of damage states by increasing PGD,the fragility curves corresponding to each damage state were plotted and interpreted in related figures.
基金supported by the Science and Technology Program of Shanxi Province(2014KJXX-18)the Spark Programs of Earthquake Sciences(XH14069)
文摘Fault-related parameters are critical for studying tectonic evolution, deformation character- istics, active tectonism, and seismic hazards. A new method of calculating reverse-fault- related parameters has been developed, which uses systematic analysis of the geometrical characteristics of normal and reverse scarps of reverse faults together with measurements of topographic profiles and fault bedding. The results show that the most suitable method of calculating fault parameters heavily relies on the specific type of fault scarp. For a reverse scarp, the size of the vertical displacement （VD） of the fault, the vertical separation （VS） of the hanging wall and the footwall, and the fault scarp height （SH）how the relationship VD ≥VS ≥ SH; conversely, for normal scarps, VD ≤ VS ≤ SH. The theoretical equations were used to study fault deformation in the Southwest Tianshan Mountain foreland basin. The results showed that, for every fault, VD ≥ VS ≥SH, which is consistent with our predicted relationship. This finding demonstrates that this method is suitable to explore structural information of reverse faults. In the study area, the vertical displacement is 1.4 times the horizontal displacement, suggesting that fiexural-slip faults may play an important role in transferring local deformation from horizontal shortening to vertical uplift. Therefore, one of the most important steps in correct calculation of reverse-fault-related parameters is selection of the proper equations by identifying the specific type of fault scarp and the corresponding calculation method.
基金Joint Seismological Science Foundation of China (105066)National Natural Science Foundation of China (40472109)the SASAKAWA Scientific Grant from the Japan Science Society.
文摘The Anninghe fault is one of the significant earthquake-generating fault zones in the Southwest China. Local historical record shows that a M2≥7 strong earthquake occurred in the year of 1536. On the basis of the detailed air-photographic interpretation and field investigation, we have acquired the following knowledge： ① The average sinistral strike-slip rate since the Late Pleistocene is about 3～7 mm/a; ② There is important reverse faulting along the fault zone besides the main left-lateral strike-slip motion, and the shortening rate across the Anninghe fault zone due to the reverse faulting is about 1.7-4.0 mm/a. If the Xianshuihe fault zone is simply partitioned into the Anninghe and Daliangshan faults, we can also get a slip rate of 3-7 mm/a along the Daliangshan fault zone, which is the same as that on the Anninghe fault zone. Moreover, on the basis of our field investigation and the latest knowledge concerning the active tectonics of Tibetan crust, we create a dynamic model for the Anninghe fault zone.
基金financed by the National Youth Sciences Foundation of China (No. 41502044)
文摘The role of authigenic clay growth in clay gouge is increasingly recognized as a key to understanding the mechanics of berittle faulting and fault zone processes,including creep and seismogenesis,and providing new insights into the ongoing debate about the frictional strength of brittle fault(Haines and van der Pluijm,2012).However,neither the conditions nor the processes which
基金Supported by the National Natural Science Foundation of China(61303214)the Science and Technology Project of China State Grid Corp(KJ15-1-32)
文摘Software fault positioning is one of the most effective activities in program debugging. In this paper, we propose a model-based fault positioning method to detect the faults of embedded program without source code. The system takes the machine code of embedded software as input and translates the code into high-level language C with the software reverse engineering program. Then, the static analysis on the high-level program is taken to obtain a control flow graph（CFG）, which is denoted as a node-tree and each node is a basic block. According to the faults found by the field testing, we construct a fault model by extracting the features of the faulty code obtained by ranking the Ochiai coefficient of basic blocks. The model can be effectively used to locate the faults of the embedded program. Our method is evaluated on ST chips of the smart meter with the corresponding source code. The experiment shows that the proposed method has an effectiveness about 87% on the fault detection.
基金This work is financed by the grants of the National Natural Science Foundation of China （Grant No 40272084, 40472101 and 40572123）.
文摘The MohroCoulomb criterion has been widely used to explain formation of fractures. However, it fails to explain large strain deformation that widely occurs in nature. There is presently a new theory, the MEMC, which is mathematically expressed as Meff = （（σ1-σ3） L.sin 2α sin α）/2, where σ1-σ3 represents the yield strength of the related rock, L is a unit length and a is the angle between σ1 and deformation bands. This criterion demonstrates that the maximum value appears at angles of ±54.7° to σ1 and there is a slight difference in the moment in the range of 55°±10°. The range covers the whole observations available from nature and experiments. Its major implications include： （1） it can be used to determine the stress state when the related deformation features formed; （2） it provides a new approach to determine the Wk of the related ductile shear zone if only the ratio of the vorticity and strain rate remains fixed; （3） It can be used to explain （a） the obtuse angle in the contraction direction of conjugate kink-bands and extensional crenulation cleavages, （b） formation of low-angle normal faults and high-angle reverse faults, （c） lozenge ductile shear zones in basement terranes, （d） some crocodile structures in seismic profiles and （e） detachment folds in foreland basins.
基金sponsored by the National Key Projects of Basic Research (Grant No. 2009CB219407)the Natural Science Foundation (Grant No. 40572067)
文摘Based on a large amount of seismic, drilling and core data, the characteristics of the early- middle Miocene submarine fans in the Baiyun Sag, northern South China Sea are investigated. By analyzing the sedimentary processes of submarine fans in SQ21 （SQ21 refers to the 3rd-order sequence with its bottom boundary 21 Ma）, a sedimentary model of the sand-rich fans is established and the main factors controlling fan deposition are detailed. The results indicate that from early to middle Miocene the Pearl River Mouth Basin developed seven 3rd-order sequences in all, with each lowstand systems tract （LST） of the sequence corresponding to submarine fans. However, only the fans in SQ13.8 and SQ21 are sand-rich fans, the others being mud-rich fans. The cores reveal that the submarine fans in the Pearl River Mouth Basin developed five lithofacies： （1） mud clast-bearing sandstone, interpreted as channel deposits; （2） typical turbidite sandstones, also interpreted as channel deposits; （3） thin-bedded sandstone and mudstone, interpreted as channel-levee complex deposits; （4） massive sandstones, interpreted as lobe deposits; （5） massive mudstone, interpreted as hemipelagic mud. The sand-rich submarine fans in the Pearl River Mouth Basin mainly developed in LST, and in LST reverse faults were active, which led to the formation of accommodation on the shelf. Different from the theory of classic sequence stratigraphy, the accommodation on the shelf captures terrigenous debris transported by the Pearl River, and the uplift at the edge of shelf serves as a ＂Linear Source＂ for the deep water area instead of the Pearl River. Therefore, the fans mainly derived from the eroded debris from the uplift. Factors controlling fan deposition include the basin＇s tectonic framework, the evolution of the slope break, relative sea-level changes as well as the evolution of the fault system, and the fans are formed under the combination of the above factors.
基金supported by the National Nature Science Foundation of China (No. 42130312)。
文摘On January 1, 2024 at 16:10:09 JST, an M_(j) 7.6 earthquake struck the Noto Peninsula in the southern part of the Sea of Japan. This location has been experiencing an earthquake swarm for more than three years. Here, we provide an overview of this earthquake, focusing on the slip distribution of the mainshock and its relationship with the preceding swarm. We also reexamined the source areas of other large earthquakes that occurred around the Sea of Japan in the past and compared them with the Matsushiro earthquake swarm in central Japan from1964 to 1968. The difference between the Matsushiro earthquake swarm and the Noto earthquake swarm is the surrounding stress field. The Matsushiro earthquake swarm was a strike-slip stress field, so the cracks in the crust were oriented vertically. This allowed fluids seeped from the depths to rise and flow out to the surface. On the other hand, the Noto area was a reverse fault stress field. Therefore, the cracks in the earth's crust were oriented horizontally. Fluids flowing underground in deep areas could not rise and spread over a wide area in the horizontal plane. This may have caused a large amount of fluid to accumulate underground, triggering a large earthquake. Although our proposed mechanism does not take into account other complex geological conditions into consideration, it may provide a simple way to explain why the Noto swarm is followed by a large earthquake while other swarms are not.
文摘Buried hill is an important exploration field in Dawangzhuang block. Because Dawangzhuang buried hill has experienced multi-stage tectonic movement, the complexity of tectonic movement determines the diversity of buried hill morphology, and the diversity of buried hill structural morphology determines its reservoir forming characteristics. Therefore, the research on the structural style and reservoir forming characteristics of Dawangzhuang buried hill is of great significance in the process of oil and gas exploration at this stage. This paper summarizes the structural style of Dawangzhuang buried hill. On this basis, 67 small fault blocks divided in the study area are classified and counted. Further, according to the seismic profile and logging data, the well data and reservoir profile of characteristic wells are counted and compared, and the reservoir forming characteristics and main controlling factors of Dawangzhuang buried hill are found. The above understanding has certain guiding significance for the further exploration of Dawangzhuang buried hill.
文摘3D geological modeling is an inevitable choice for coal exploration to adapt to the transformation of coal mining for green, fine, transparent and Intelligent mining. In the traditional Coalfield exploration geological reports, the spatial expression form for the coal seams and their surrounding rocks are 2D maps. These 2D maps are excellent data sources for constructing 3D geological models of coal field exploration areas. How to construct 3D models from these 2D maps has been studying in coal exploration industry for a long time, and still no breakthrough has been achieved so far. This paper discusses the principle, method and software design idea of constructing 3D geological model of an exploration area with 2D maps made by AutoCAD/MapGIS. At first, the paper analyzes 3D geological surface expression mode in 3D geological modeling software. It is pointed out that although contour method has unique advantages in coal field exploration, TIN (Triangular Irregular Network) is still the standard configuration of 3D modeling software for coal field. Then, the paper discusses the method of 2D line features obtaining elevation and upgrading 2D curve to 3D curve. Next, the method of semi-automatic partition is introduced to build the boundary ring of the surface patch, that is, the user clicks and selects the line feature to build the outer boundary ring of the surface patch. Then, Auto-process method for fault line inside of the outer boundary ring is discussed, it including construction of fault ring, determining fault ring being normal fault ring or reverse fault ring and an algorithm of dealing with normal fault ring. An algorithm of dealing with reverse fault ring is discussed detailly, the method of expanding reverse fault ring and dividing the duplicate area in reverse fault into two portions is introduced. The paper also discusses the method of extraction ridge line/valley line, the construction of fault plane, the construction of stratum and coal body. The above ideas and methods have been initially implemented in the “3D modeling platform for coal field exploration” software, and applied to the 3D modeling practice of data from several coal field exploration areas in Ningxia, Shanxi, Qinghai, etc.
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supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2021SP315)the National Natural Science Foundation of China(Grant No.42172229)。
文摘The Cenozoic structural architecture and geodynamic mechanism of the Longmen Shan structural belt are essential for understanding the tectonic evolution of the eastern Tibetan Plateau,but remain controversial.Models of different manners of deformation in different lithospheric levels have been proposed.For example,the crustal extrusion model suggests that Late Cenozoic deformation of the Longmen Shan was dominated by crustal shortening,whereas the channel flow model proposes lower crustal thickening and flow,accommodated by frontal shortening and hinterland extension.This study compiles previously published low-temperature thermochronology data from the Longmen Shan to constrain spatial changes in rock exhumation and test previous geodynamic models.The results show that exhumation increases abruptly across the Yingxiu-Beichuan fault,suggesting the fault is the main thrust boundary between the Longmen Shan and the Sichuan Basin to the east.Further,younger Late Cenozoic cooling ages and faster exhumation are observed on the hinterland Wenchuan-Maowen fault,where a dichotomy of ages on the hanging wall versus footwall suggests Late Cenozoic thrust activity.In addition,towards the hinterland to the west,exhumation rates decrease threefold over a distance of about 80 km.Such an exhumation pattern indicates a westward decrease of tectonic uplift,providing the regional topography reached a steady-state,whereby exhumation is in balance with tectonic uplift.The observed spatial changes in exhumation support a listric crustal configuration where reverse faults in the Longmen Shan merge gradually into a gentle detachment seated at depth.Results of this study support a revised upper crustal shortening model,where the triangular Songpan-Ganzi terrane,bounded by two left-lateral strike-slip faults(Ganzi-Xianshuihe fault to the south and eastern Kunlun fault to the north),might have extruded eastward towards the western margin of the Sichuan Basin along the listric Longmen Shan faults.
