Through the statistical analysis of earthquake distribution along 51 strike-sli p active fault segments on the Chinese continent, we found that strong earthquak e distribution along the seismogenic fault segments is i...Through the statistical analysis of earthquake distribution along 51 strike-sli p active fault segments on the Chinese continent, we found that strong earthquak e distribution along the seismogenic fault segments is inhomogeneous and the dis tribution probability density p(K) can be stated as p(K)=1.1206e -3.947K in which K=S/(L/2), S refers to the distance from earthquake epicenter to the center of a fault segment, L is the length of the fault segment. The above model can be utilized to modify the probability density of earthquake occurrence of t he maximum magnitude interval in a potential earthquake source. Nevertheless, it is only suitable for those potential earthquake sources delineated along a sing le seismogenic fault. This inhomogeneous model has certain effects on seismic risk assessment, especia ll y for those potential earthquake sources with higher earthquake reoccurrence rat es of the maximum magnitude interval. In general, higher reoccurrence rate of th e maximum magnitude interval and lower exceeding probability level may bring lar ger difference of the results in seismic risk analysis by adopting the inhomogen eous model, the PGA values increase inner the potential earthquake source, but r educe near the vicinity and out of the potential earthquake source. Taking the T angyin potential earthquake source as an example, with exceeding probability of 10% and 2% in 50 years, the difference of the PGA values between inhomogeneous m odel and homogenous models can reach 12%.展开更多
By computing and classifying the data of gully offset obtained from field surveys along the Tianjingshan fault zone and estimating the ages of three types of gullies,the strike-slip rates along the fault zone are disc...By computing and classifying the data of gully offset obtained from field surveys along the Tianjingshan fault zone and estimating the ages of three types of gullies,the strike-slip rates along the fault zone are discussed in different time intervals and fault segments.The results suggest that the intensity of activity along the fault zone is not strong,but the differences between different time intervals and fault segments since the late Pleistocene have been obvious.The average rates range from 0.23 mm/a to 1.62 mm/a.The largest average rate is 1.40 mm/a,which occurred in the early and middle of late Pleistocene along the western segment of the fault zone.Since the late stage of the late Pleistocene,the center of faulting activity of the fault zone has shifted to the middle segment,and the average slip rates range have changed from 1.30 mm/a to 1.63 mm/a.展开更多
Mountain front faults form the boundary between mountains and adjacent plains.These faults can propagate toward the plains and escalate the risk of seismic hazard for near cities.The North Tehran Fault(NTF)is a mounta...Mountain front faults form the boundary between mountains and adjacent plains.These faults can propagate toward the plains and escalate the risk of seismic hazard for near cities.The North Tehran Fault(NTF)is a mountain front fault bordering the Central Alborz with Tehran and Karaj plains.Structural and morphotectonic data from interpreted aerial photographs,satellite images,airborne geomagnetic data as well as field surveying have been used for detailed segmentation and evolution of the North Tehran Fault.This resulted in identification of the fault segments as the Niknamdeh,Darband,Darakeh-Garmdarreh,and Karaj from east to west.Active kinematics of these segments includes both thrusting and left-lateral components;but the dominant component is different among the segments.The Niknamdeh segment is connected to the Mosha Fault with a hard linkage,while its connection with the Darband segment is a widespread deformation zone.The connection zone between the Darband and Darakeh-Garmdarreh segments has the highest density of minor faults along the North Tehran Fault.The boundary of the Darakeh-Garmdarreh and Karaj segments is controlled by the F-3 transverse fault that has offset the NTF for~3 km right-laterally.The NTF has inverted from normal to dextral oblique fault in Miocene.The fault kinematics has changed from dextral to sinistral in Pliocene-Quaternary.Further regional oblique convergence resulted in minor fault reactivation such as relay ramp breaching faults,propagation of several footwall branches and hangingwall bypasses geometrical change of alluvial fans,and transfer of deformation front southwardly to the Tehran and Karaj plains.The findings of this paper are also applicable to other active oblique converging mountain fronts,inverted mountain front faults and the transition of deformation from these structures to the foreland basin.展开更多
This article presents an interpretation of the seismic source mechanisms for 905 earthquakes with MS>2.0,occurring in the central and southern sections of the Tan-Lu Fault Zone and its adjacent areas from 1970 to 2...This article presents an interpretation of the seismic source mechanisms for 905 earthquakes with MS>2.0,occurring in the central and southern sections of the Tan-Lu Fault Zone and its adjacent areas from 1970 to 2023.Utilizing the damped stress tensor method,we have inverted the spatial characteristics of the stress field variations in this study area,at a resolution of 1.0°×1.0°.The results indicate that the maximum principal stress direction within the central and southern sections of the Tan-Lu Fault Zone exhibits a spatially continuous change,rotating counterclockwise from East-West(EW)to Northeast-East(NEE),albeit with local variations.When dividing along the Tan-Lu Fault Zone,it is observed that on its western side—the North China block—a near EW stress field predominates.In contrast,on its eastern side—the Ludong-Huanghai Block—stress fields primarily exhibit NEE and Northeast-East(NE)orientations,underscoring the role of the Tan-Lu Fault Zone as a significant boundary between tectonic blocks.In regions located between latitudes 30°-34°N and longitudes 113°-115°E on the western side of these fault zone sections,maximum principal stress follows a radial distribution pattern indicative of a complex stress field.Conversely,on the eastern side of this fault zone,maximum principal stress direction remains relatively consistent,primarily displaying NEE and NE distributions.This reflects the fact that this area is situated under a tectonic background characterized by near NEE-NE direction for the Ludong-Huanghai Block.However,within an area bounded by latitudes 30°-32°N and longitudes 120°-122°E on the eastern flank of the Tan-Lu Fault Zone,maximum principal stress direction appears more intricate,with radial distribution patterns suggesting influences not only from near EW-NEE movements associated with the North China Block,but also from westward subduction processes related to Philippine Sea plate dynamics.Through our analysis of historical earthquakes in this region,we conclude that the moderate to strong seismic activity within this area is significantly related to the tectonic stress environment,with regions of complex tectonic stress often being the most seismically active.展开更多
No earthquake of magnitude six or greater has been recorded historically in the southern segment of the Red River Fault(RRF).This absence constitutes a significant seismic gap, suggesting a risk of future strong earth...No earthquake of magnitude six or greater has been recorded historically in the southern segment of the Red River Fault(RRF).This absence constitutes a significant seismic gap, suggesting a risk of future strong earthquakes. The China Earthquake Science Experimental Site intends to conduct drilling exploration in this area, which necessitates improved knowledge of the fault zone's geometric distribution characteristics and deep structure. We obtained and analyzed audio and broadband magnetotelluric(MT) data collected at one of the alternative drilling stations(in the Dazhai Village of Honghe County). We have used these data to obtain a highresolution 3-D electrical model of this study area's subsurface to a depth of 5 km. We report that the electrical structure from the surface to 0.5 km is relatively complex, characterized by alternating high and low resistivity;below 0.5 km, the electrical structure becomes more simplified. The RRF extends northwest-southeast orientation along the high and low resistivity boundary, dipping northeastward. The electrical structure of the Red River Valley, which the fault zone traverses, reveals low resistivity characteristics with a lateral width of up to2 km. This study offers critical electromagnetic constraints that enhance our understanding of the tectonic characteristics of the RRF. The findings will inform and aid in the design of drilling plans for the southern segment of the RRF region.展开更多
Seismic data plays a pivotal role in fault detection,offering critical insights into subsurface structures and seismic hazards.Understanding fault detection from seismic data is essential for mitigating seismic risks ...Seismic data plays a pivotal role in fault detection,offering critical insights into subsurface structures and seismic hazards.Understanding fault detection from seismic data is essential for mitigating seismic risks and guiding land-use plans.This paper presents a comprehensive review of existing methodologies for fault detection,focusing on the application of Machine Learning(ML)and Deep Learning(DL)techniques to enhance accuracy and efficiency.Various ML and DL approaches are analyzed with respect to fault segmentation,adaptive learning,and fault detection models.These techniques,benchmarked against established seismic datasets,reveal significant improvements over classical methods in terms of accuracy and computational efficiency.Additionally,this review highlights emerging trends,including hybrid model applications and the integration of real-time data processing for seismic fault detection.By providing a detailed comparative analysis of current methodologies,this review aims to guide future research and foster advancements in the effectiveness and reliability of seismic studies.Ultimately,the study seeks to bridge the gap between theoretical investigations and practical implementations in fault detection.展开更多
On September 5,2022,the Luding M6.8 earthquake occurred in the Moxi-Shimian segment of the Xianshuihe fault,coinciding with the historical ruptured zone of the 1786 Moxi earthquake.Its seis-mogenic environment provide...On September 5,2022,the Luding M6.8 earthquake occurred in the Moxi-Shimian segment of the Xianshuihe fault,coinciding with the historical ruptured zone of the 1786 Moxi earthquake.Its seis-mogenic environment provides a foundation for comprehending the mechanism of the earthquake and its future hazard.In the Moxi-Shimian segment,we establish a series of near-field Global Navigation Satellite Systems(GNsS)stations to enhance the spatial resolution of observational data for the inversion of the interseismic kinematic parameters.In this study,with an elastic screw dislocation model con-strained by GNsS observations,the slip rate of the Moxi-Shimian segment is estimated to be 10.9±1.0 mm/yr,while the locking depth is 15.7±6.2 km.Additionally,we utilize a block-dislocation model to invert the interseismic fault coupling along the Kangding-Moxi-Shimian segment.The result indicates a gradual deepening of the locking depth along the section from Kangding to Shimian.The coseismic rupture of the 2022 event occurred within the high coupling regions in the Kangding-Moxi-Shimian segment,which indicates that the rupture kinematics in this event might be controlled by the interseismic deformation.The seismic moment accumulated within the ruptured zone of the Luding earthquake since 1786 ranges in[1.42-3.40]×10^(19) N-m,which is significantly greater than the seismic moment released during the 2022 event.As a result,we infer that the Luding earthquake released only a portion of the accumulated energy within the original rupture zone since 1786,indicating that the 2022 event has not caused a complete rupture in the Moxi-Shimian segment.Consequently,there remains a substantial seismic hazard in this area.展开更多
The western Liaodong （辽东） Bay subbasin displays examples of segment, linkage of extensional fault, and fault-related folds. The Liaoxi （辽西） extensional fault system consists of a series of NNE- and NE-trending...The western Liaodong （辽东） Bay subbasin displays examples of segment, linkage of extensional fault, and fault-related folds. The Liaoxi （辽西） extensional fault system consists of a series of NNE- and NE-trending segments that were linked through relay ramps. The fault hanging walls are characterized by a series of en echelon synclines with axial traces sub-parallel to the faults. The synclines are doubly plunging located on the hanging wall of normal faults, with the strata dip sub-parallel to the fault. These folds result from along-strike displacement variations of the individual fault segments, as well as from extensional fault-related folding. In the study area, the synclines are separated by transverse intra-basin highs and relay ramps that formed where segment linkage occurred. These hanging wall synclines and their relation to fault displacement variations indicate that they are formed by extensional fault-related fold.展开更多
Strong earthquakes generally rupture along active faults,and associated ground motion can cause earthquake disasters,property losses,and casualties from kilometers to tens of kilometers away.Therefore,one of the most ...Strong earthquakes generally rupture along active faults,and associated ground motion can cause earthquake disasters,property losses,and casualties from kilometers to tens of kilometers away.Therefore,one of the most effective ways to find earthquake’s dangerous parts of faults is to study the seismic hazards on fault segments.After that,we can also evaluate the probabilities of landslides hazard,property losses,and casualties.In this study,using fault slip rates and magnitude-frequency relationship as constraints,we calculated the earthquake occurrence rates for the segments along the Xianshuihe-Xiaojiang fault zone.We obtained 11 sites of single-segment or multi-segment rupturing risk.We also provided these potential events conditional probabilities in the next 30 years.For the 11 potential earthquakes,we calculated the property loss of residential buildings in the ground motion field.The most significant property loss is CNY 7.65 billion caused by the single-segment rupturing of the F19 segment on the Anninghe fault.We applied the deep learning neural network method in predicting the number of casualties for the potential earthquakes,showing that the most significant event is the multi-segment rupturing of the F29 and F30 segments on the Anninghe fault with the predicted death number of 279-317.We also evaluated the probabilities of earthquake landslides after the potential earthquakes.The results show that areas with intense compressional tectonic stress are highly unstable and prone to earthquake induced landslides,including the southern section of the Yuke fault,the southern section of the Xianshuihe fault,and the conjugated area between the southern section of the Daliangshan fault and the Lianfeng fault.These areas have a considerable number of earthquake landslides with probabilities>10%.The methodology and results will give us a new effective way of applying active fault data in earthquake hazard and risk analysis and provide a scientific path for earthquake prevention,disaster reduction,and emergency rescue preparation.展开更多
From the results of researches of active faults in resent years, a correlation analysis between segments of the faults according to surface ruptures in nine historical strong earthquakes occurring in downfaulted syste...From the results of researches of active faults in resent years, a correlation analysis between segments of the faults according to surface ruptures in nine historical strong earthquakes occurring in downfaulted system and active structures around Ordos block is conducted in paper. The result shows that there is a good correlation between them, except few individual data that have more uncertain parameters. It shows that intensity and segments of surface ruptures in these strong earthquakes are intrinsically related with the active structures. These strong earthquakes produced stable and unstable rupture boundaries of characteristic-earthquake type and successive occurrence of strong earthquakes on the different boundary faults in the same tectonic unit.展开更多
On the basis of the recent geological surveys and the relevant studies of the Xianshuihe fault zone, this paper analyzes the seismogenic mechanism of some faults and characteristic morphology on the fault zone by the ...On the basis of the recent geological surveys and the relevant studies of the Xianshuihe fault zone, this paper analyzes the seismogenic mechanism of some faults and characteristic morphology on the fault zone by the boundary element method and discusses the fault segmentation and the related distribution of the earthquake ruptures. The main conclusions are: For the first order segmentation, the Xianshuihe fault zone can be divided into three major segments (the northwestern Luhuo-Qianning segment, the middle linking fracture region and the southeastern Kangding segment). Among them, the differences are not only in geometry and structure, but also in mechanical property and dynamics. Some of the characteristic morphologies on the Xianshuihe fault zone reflect the effects in cumulative deformation due to long-term fault movement, and reveal the fault segmentation in different orders. Such morphologies control, to some extent, the developments and the distributions of the earthquake ruptures on the fault zone.展开更多
Segmentation of the thrust fault zone is a basic problem for earthquake hazard evaluation. The Yingjing-Mabian-Yanjin thrust fault zone is an important seismic belt NW-trending in the southeast margin of the Qinghal-X...Segmentation of the thrust fault zone is a basic problem for earthquake hazard evaluation. The Yingjing-Mabian-Yanjin thrust fault zone is an important seismic belt NW-trending in the southeast margin of the Qinghal-Xizang （Tibet） plateau. The longitudinal faults in the thrust zone are mainly of the thrust slipping type. The late Quaternary motion modes and displacement rates are quite different from north to south. Investigation on valleys across the fault shows that the transverse faults are mainly of dextral strike-slipping type with a bit dip displacement. Based on their connections with the longitudinal faults, three types of transverse faults are generalized, namely： the separate fault, the transform fault and the tear fault, and their functions in the segmentation of the thrust fault zone are compared. As the result, the Yingjing-Mabian-Yanjin thrust fault zone is divided into three segments, and earthquakes occurring in these three segments are compared. The tri-section of the Yingjing-Mabian-Yanjin thrust fault zone identified by transverse fault types reflects, on the one hand, the differences in slip rate, earthquake magnitude and pace from each segment, and the coherence of earthquake rupturing pace on the other hand. It demonstrates that the transverse faults control the segmentation to a certain degree, and each type of the transverse faults plays a different role.展开更多
To investigate the recurrence behaviors of segment-rupturing eathquakes on active faults of the Chinese mainland, thispaper analyzes quantitatively earthquake history of 19 fault segments based on earthquake dam of mu...To investigate the recurrence behaviors of segment-rupturing eathquakes on active faults of the Chinese mainland, thispaper analyzes quantitatively earthquake history of 19 fault segments based on earthquake dam of multi-cyclerecurrences. The result shows that, for these fault segments, eanhquake recurring at previous locations is mainlycharacterized by both quasi-periodic (in a ratio of about) and time-predictable (in a ratio of about) behaviors.For the first behavior. intrinsic uncertainty of recurrence interval accounts for 0. 15-0.40 of the average interval, andmagnitudes of event vary from cycle to cycle within the range of the mean magnitUde t0.5. For the second behavior,intrinsic uncertainty of recurrence interval ranges mostly from 0. 19 to 0.40 of the average interval, and for successivetwo cycles the maximum change of event magnitudes is as much as 1.7 magnitude-units. In addition, for a few casesthe first behavior coexists along with either the second or the slip-predictable behaviors.展开更多
As one of the longest strike-slip fault in Asia,the Altyn Tagh Fault（ATF）defines the northern boundary of the Tibetan Plateau and plays a significant role inaccommodating the deformation resulting from the IndiaAsia...As one of the longest strike-slip fault in Asia,the Altyn Tagh Fault（ATF）defines the northern boundary of the Tibetan Plateau and plays a significant role inaccommodating the deformation resulting from the IndiaAsia convergence.展开更多
By systemic processing, comprehensive analysis, and interpretation of gravity data, we confirmed the existence of the west segment of the coastal fault zone(west of Yangjiang to Beibu Bay) in the coastal region of Sou...By systemic processing, comprehensive analysis, and interpretation of gravity data, we confirmed the existence of the west segment of the coastal fault zone(west of Yangjiang to Beibu Bay) in the coastal region of South China. This showed an apparent high gravity gradient in the NEE direction, and worse linearity and less compactness than that in the Pearl River month. This also revealed a relatively large curvature and a complicated gravity structure. In the finding images processed by the gravity data system, each fault was well reflected and primarily characterized by isolines or thick black stripes with a cutting depth greater than 30 km. Though mutually cut by NW-trending and NE-trending faults, the apparent NEE stripe-shaped structure of the west segment of the coastal fault zone remained unchanged,with good continuity and an activity strength higher than that of NW and NE-trending faults. Moreover,we determined that the west segment of the coastal fault zone is the major seismogenic structure responsible for strong earthquakes in the coastal region in the border area of Guangdong, Guangxi, and Hainan.展开更多
By means of differentiation of remote sensing image, field seismo-geological survey, analysis on drilling explora- tion materials, sampling and dating of rock samples, combined with seismicity and microscopic tectoni...By means of differentiation of remote sensing image, field seismo-geological survey, analysis on drilling explora- tion materials, sampling and dating of rock samples, combined with seismicity and microscopic tectonic analysis, this paper studies the recent activity of Chihe segment of the Tanlu fault zone. The result indicates that the Chihe fault segment undergoes the deformation alternately in the mode of stick slip and creep during Late Quaternary, and its recent activity is mainly creep.展开更多
This study＇s objective was to investigate the Guguan-Xiangong Fault, which lies in the southern Liupanshan area, through satellite image interpretation and field observations. Guguan- Xiangong Fault is divided into f...This study＇s objective was to investigate the Guguan-Xiangong Fault, which lies in the southern Liupanshan area, through satellite image interpretation and field observations. Guguan- Xiangong Fault is divided into five subsegments; among these, the Badu-Longwei segment has been the most recently active. The geomorphic features of the Badu-Longwei segment are clearly displayed, including multiple high fault scarps with fresh bedrock free faces. There is significant evidence for Holocene activity of the three fault sections, located in Renhuashu, Tianjiagou, and Xinjiecun respectively. The three sections feature distinct episodic deposition and fault scratches. Based on 14C- dating and field observations on the three fault sections, two or more paleoearthquakes across the Badu-Longwei fault segment are ascertained, between 5874±116 and 5430±140 a BP, and after 2037±83 a BP respectively. The Badu-Longwei segment of the Guguan-Xiangong Fault is preliminarily extrapolated as the seismogenic structure of the 600 A.D. Qin-Long earthquake.展开更多
Objective The uplift process and uplift mechanism of the Tibetan Plateau has been a research focus among geologists in recent years. This work put emphasis on the Cenozoic exhumation histories of the blocks bounded by...Objective The uplift process and uplift mechanism of the Tibetan Plateau has been a research focus among geologists in recent years. This work put emphasis on the Cenozoic exhumation histories of the blocks bounded by the major faults at the central segment of the Longmenshan thrust belt, and the vertical faulting history, including the starting time and the total vertical displacement, of the major faults. Then we quantitatively established a complete active process for the central segment of the Longmenshan thrust belt, combining with the previous geophysical data in the deep and geologcial data. This study is critical for deeply and completely understanding the Cenozoic uplift history of the Longmenshan, and also provides thermochronology constraints to the different models for the uplift of the eastern margin of the Tibetan Plateau.展开更多
In this study, Landsat 5 Thematic Mapper (TM) and SPOT HRV Panchromatic data were analysed to determine the geometry of an active fault segment (the Ganos segment) in Gazikoy-Saros region, west of Marmara Sea, Turkey....In this study, Landsat 5 Thematic Mapper (TM) and SPOT HRV Panchromatic data were analysed to determine the geometry of an active fault segment (the Ganos segment) in Gazikoy-Saros region, west of Marmara Sea, Turkey. Gazikoy-Saros/Ganos segment is a part of North Anatolian Fault Zone (NAFZ). North-Anatolian fault is considered to be one of the most important active strike-slip faults in the world. Thus far in relevant researches based on Gazikoy-Saros segment a single straight fault line representation is used on the fault descriptive geological maps. This study, with the aid of enhanced remotely sensed data aims to reveal the linear details of the NAFZ fault segment, which subsequently were superposed with a Digital Elevation Model (DEM) data. Respectively, using these data the surface geometry expression of Gazikoy-Saros fault segment was detailed and remapped. According to the results of the analysis two small releasing steps were identified on this segment. The first one is situated between Mürseli and Güzelkoy villages, and the second one is between Mürseli and Yorguc villages. In addition to this, it is found that the fault strike bends approximately 7° further to in south-eastern (SE) direction between Yenikoy and Sofular villages. This angular change was defined with the advantage of multi-angular viewing capability of the multi-satellite sensors and DEM data. The newly generated surface geometry expression of Ganos segment was compared with Global Positioning System (GPS) velocity vectors.展开更多
In order to obtain deformation parameters in the south segment of Longmenshan fault zone,Euler datum transformation and the least square collocation for data interpolation and smoothing are used to process GPS displac...In order to obtain deformation parameters in the south segment of Longmenshan fault zone,Euler datum transformation and the least square collocation for data interpolation and smoothing are used to process GPS displacement time series data in the south segment of Longmenshan fault zone,and the rigid and elastic-plastic block motion model is used to calculate the strain parameters in each subarea. Conjoint analysis of displacement,velocity of each station and strain parameters of each subarea reveals that the influence of the Wenchuan earthquake on the south segment of Longmenshan fault zone increases from southeast to northwest,causing a highest deformation rate 6 times the background value and heightening the influence of the hidden faults on the difference of the earth surface along its two sides,which leads to the seismic risk of the southern segment increasing from north to south. The comparison of seismic risk among subareas based on the tectonic and seismicity background indicates that the most dangerous area is on the southeast of Longmenshan faults,and the background strain accumulation and the promoting effect of the Wenchuan earthquake advanced the occurrence of Lushan earthquake and the sinistral strike-slip on the rupture plane. The Wenchuan earthquake also caused a slight two-year long continuous strain release in the south segment of Xianshuihe fault,but the influence is far less than the effect of the compressive strain caused by the Sichuan-Yunnan block.展开更多
文摘Through the statistical analysis of earthquake distribution along 51 strike-sli p active fault segments on the Chinese continent, we found that strong earthquak e distribution along the seismogenic fault segments is inhomogeneous and the dis tribution probability density p(K) can be stated as p(K)=1.1206e -3.947K in which K=S/(L/2), S refers to the distance from earthquake epicenter to the center of a fault segment, L is the length of the fault segment. The above model can be utilized to modify the probability density of earthquake occurrence of t he maximum magnitude interval in a potential earthquake source. Nevertheless, it is only suitable for those potential earthquake sources delineated along a sing le seismogenic fault. This inhomogeneous model has certain effects on seismic risk assessment, especia ll y for those potential earthquake sources with higher earthquake reoccurrence rat es of the maximum magnitude interval. In general, higher reoccurrence rate of th e maximum magnitude interval and lower exceeding probability level may bring lar ger difference of the results in seismic risk analysis by adopting the inhomogen eous model, the PGA values increase inner the potential earthquake source, but r educe near the vicinity and out of the potential earthquake source. Taking the T angyin potential earthquake source as an example, with exceeding probability of 10% and 2% in 50 years, the difference of the PGA values between inhomogeneous m odel and homogenous models can reach 12%.
基金This project was sponsored by the State Seismological Bureau (85-02-3-3), China
文摘By computing and classifying the data of gully offset obtained from field surveys along the Tianjingshan fault zone and estimating the ages of three types of gullies,the strike-slip rates along the fault zone are discussed in different time intervals and fault segments.The results suggest that the intensity of activity along the fault zone is not strong,but the differences between different time intervals and fault segments since the late Pleistocene have been obvious.The average rates range from 0.23 mm/a to 1.62 mm/a.The largest average rate is 1.40 mm/a,which occurred in the early and middle of late Pleistocene along the western segment of the fault zone.Since the late stage of the late Pleistocene,the center of faulting activity of the fault zone has shifted to the middle segment,and the average slip rates range have changed from 1.30 mm/a to 1.63 mm/a.
文摘Mountain front faults form the boundary between mountains and adjacent plains.These faults can propagate toward the plains and escalate the risk of seismic hazard for near cities.The North Tehran Fault(NTF)is a mountain front fault bordering the Central Alborz with Tehran and Karaj plains.Structural and morphotectonic data from interpreted aerial photographs,satellite images,airborne geomagnetic data as well as field surveying have been used for detailed segmentation and evolution of the North Tehran Fault.This resulted in identification of the fault segments as the Niknamdeh,Darband,Darakeh-Garmdarreh,and Karaj from east to west.Active kinematics of these segments includes both thrusting and left-lateral components;but the dominant component is different among the segments.The Niknamdeh segment is connected to the Mosha Fault with a hard linkage,while its connection with the Darband segment is a widespread deformation zone.The connection zone between the Darband and Darakeh-Garmdarreh segments has the highest density of minor faults along the North Tehran Fault.The boundary of the Darakeh-Garmdarreh and Karaj segments is controlled by the F-3 transverse fault that has offset the NTF for~3 km right-laterally.The NTF has inverted from normal to dextral oblique fault in Miocene.The fault kinematics has changed from dextral to sinistral in Pliocene-Quaternary.Further regional oblique convergence resulted in minor fault reactivation such as relay ramp breaching faults,propagation of several footwall branches and hangingwall bypasses geometrical change of alluvial fans,and transfer of deformation front southwardly to the Tehran and Karaj plains.The findings of this paper are also applicable to other active oblique converging mountain fronts,inverted mountain front faults and the transition of deformation from these structures to the foreland basin.
基金supported by the National Natural Science Foundation of China(Grant Nos.41802224)Science for Earthquake Resilience of China Earthquake Administration(Grant Nos.XH23019YC and Nos.XH24021C)+2 种基金Joint Open Fund of Mengcheng National Geophysical Observatory(Grant Nos.MENGO-202306)Key R&D and Achievement Transformation Projects of the Science and Technology Program in Wuhu City,Anhui Province(2023yf007)Open Fund of Wuhan,Gravitation and Solid Earth Tides,National Observation and Research Station(Grant Nos.WHYWZ202209).
文摘This article presents an interpretation of the seismic source mechanisms for 905 earthquakes with MS>2.0,occurring in the central and southern sections of the Tan-Lu Fault Zone and its adjacent areas from 1970 to 2023.Utilizing the damped stress tensor method,we have inverted the spatial characteristics of the stress field variations in this study area,at a resolution of 1.0°×1.0°.The results indicate that the maximum principal stress direction within the central and southern sections of the Tan-Lu Fault Zone exhibits a spatially continuous change,rotating counterclockwise from East-West(EW)to Northeast-East(NEE),albeit with local variations.When dividing along the Tan-Lu Fault Zone,it is observed that on its western side—the North China block—a near EW stress field predominates.In contrast,on its eastern side—the Ludong-Huanghai Block—stress fields primarily exhibit NEE and Northeast-East(NE)orientations,underscoring the role of the Tan-Lu Fault Zone as a significant boundary between tectonic blocks.In regions located between latitudes 30°-34°N and longitudes 113°-115°E on the western side of these fault zone sections,maximum principal stress follows a radial distribution pattern indicative of a complex stress field.Conversely,on the eastern side of this fault zone,maximum principal stress direction remains relatively consistent,primarily displaying NEE and NE distributions.This reflects the fact that this area is situated under a tectonic background characterized by near NEE-NE direction for the Ludong-Huanghai Block.However,within an area bounded by latitudes 30°-32°N and longitudes 120°-122°E on the eastern flank of the Tan-Lu Fault Zone,maximum principal stress direction appears more intricate,with radial distribution patterns suggesting influences not only from near EW-NEE movements associated with the North China Block,but also from westward subduction processes related to Philippine Sea plate dynamics.Through our analysis of historical earthquakes in this region,we conclude that the moderate to strong seismic activity within this area is significantly related to the tectonic stress environment,with regions of complex tectonic stress often being the most seismically active.
基金supported by research grants from the National Institute of Natural Hazards, MEMC (ZDJ2020-13)the Innovation Team Project from National Institute of Natural Hazards, MEMC (2023-JBKY-59)the National Natural Science Foundation of China (42174093)。
文摘No earthquake of magnitude six or greater has been recorded historically in the southern segment of the Red River Fault(RRF).This absence constitutes a significant seismic gap, suggesting a risk of future strong earthquakes. The China Earthquake Science Experimental Site intends to conduct drilling exploration in this area, which necessitates improved knowledge of the fault zone's geometric distribution characteristics and deep structure. We obtained and analyzed audio and broadband magnetotelluric(MT) data collected at one of the alternative drilling stations(in the Dazhai Village of Honghe County). We have used these data to obtain a highresolution 3-D electrical model of this study area's subsurface to a depth of 5 km. We report that the electrical structure from the surface to 0.5 km is relatively complex, characterized by alternating high and low resistivity;below 0.5 km, the electrical structure becomes more simplified. The RRF extends northwest-southeast orientation along the high and low resistivity boundary, dipping northeastward. The electrical structure of the Red River Valley, which the fault zone traverses, reveals low resistivity characteristics with a lateral width of up to2 km. This study offers critical electromagnetic constraints that enhance our understanding of the tectonic characteristics of the RRF. The findings will inform and aid in the design of drilling plans for the southern segment of the RRF region.
文摘Seismic data plays a pivotal role in fault detection,offering critical insights into subsurface structures and seismic hazards.Understanding fault detection from seismic data is essential for mitigating seismic risks and guiding land-use plans.This paper presents a comprehensive review of existing methodologies for fault detection,focusing on the application of Machine Learning(ML)and Deep Learning(DL)techniques to enhance accuracy and efficiency.Various ML and DL approaches are analyzed with respect to fault segmentation,adaptive learning,and fault detection models.These techniques,benchmarked against established seismic datasets,reveal significant improvements over classical methods in terms of accuracy and computational efficiency.Additionally,this review highlights emerging trends,including hybrid model applications and the integration of real-time data processing for seismic fault detection.By providing a detailed comparative analysis of current methodologies,this review aims to guide future research and foster advancements in the effectiveness and reliability of seismic studies.Ultimately,the study seeks to bridge the gap between theoretical investigations and practical implementations in fault detection.
基金supported by Open Fund of Wuhan,Gravitation and Solid Earth Tides,National Observation and Research Station(WHYWZ202301)Scientific Research Fund from Institute of Seismology,CEA and National Institute of Natural Hazards,Ministry of Emergency Management of China grants IS202216316 and IS202226318+1 种基金State Key Laboratory of Geodesy and Earth's Dynamics,Innovation Academy for Precision Measurement Science and Technology,CAS SKLGED2023-2-5Science for Earthquake Resilience grant XH20038,and NSFC grant 42074015.
文摘On September 5,2022,the Luding M6.8 earthquake occurred in the Moxi-Shimian segment of the Xianshuihe fault,coinciding with the historical ruptured zone of the 1786 Moxi earthquake.Its seis-mogenic environment provides a foundation for comprehending the mechanism of the earthquake and its future hazard.In the Moxi-Shimian segment,we establish a series of near-field Global Navigation Satellite Systems(GNsS)stations to enhance the spatial resolution of observational data for the inversion of the interseismic kinematic parameters.In this study,with an elastic screw dislocation model con-strained by GNsS observations,the slip rate of the Moxi-Shimian segment is estimated to be 10.9±1.0 mm/yr,while the locking depth is 15.7±6.2 km.Additionally,we utilize a block-dislocation model to invert the interseismic fault coupling along the Kangding-Moxi-Shimian segment.The result indicates a gradual deepening of the locking depth along the section from Kangding to Shimian.The coseismic rupture of the 2022 event occurred within the high coupling regions in the Kangding-Moxi-Shimian segment,which indicates that the rupture kinematics in this event might be controlled by the interseismic deformation.The seismic moment accumulated within the ruptured zone of the Luding earthquake since 1786 ranges in[1.42-3.40]×10^(19) N-m,which is significantly greater than the seismic moment released during the 2022 event.As a result,we infer that the Luding earthquake released only a portion of the accumulated energy within the original rupture zone since 1786,indicating that the 2022 event has not caused a complete rupture in the Moxi-Shimian segment.Consequently,there remains a substantial seismic hazard in this area.
基金supported by the project of the State Key Labo-ratory of Petroleum Resource and Prospecting and Tianjin Oil Company, CNOOC Limited (No. SC06TJ-TQL-004)
文摘The western Liaodong （辽东） Bay subbasin displays examples of segment, linkage of extensional fault, and fault-related folds. The Liaoxi （辽西） extensional fault system consists of a series of NNE- and NE-trending segments that were linked through relay ramps. The fault hanging walls are characterized by a series of en echelon synclines with axial traces sub-parallel to the faults. The synclines are doubly plunging located on the hanging wall of normal faults, with the strata dip sub-parallel to the fault. These folds result from along-strike displacement variations of the individual fault segments, as well as from extensional fault-related folding. In the study area, the synclines are separated by transverse intra-basin highs and relay ramps that formed where segment linkage occurred. These hanging wall synclines and their relation to fault displacement variations indicate that they are formed by extensional fault-related fold.
基金supported by the National Natural Science Foundation of China(Grant Nos.41941016,42074064,and U2039201)the National Institute of Natural Hazards,Ministry of Emergency Management of China(Grant No.ZDJ2020-14).
文摘Strong earthquakes generally rupture along active faults,and associated ground motion can cause earthquake disasters,property losses,and casualties from kilometers to tens of kilometers away.Therefore,one of the most effective ways to find earthquake’s dangerous parts of faults is to study the seismic hazards on fault segments.After that,we can also evaluate the probabilities of landslides hazard,property losses,and casualties.In this study,using fault slip rates and magnitude-frequency relationship as constraints,we calculated the earthquake occurrence rates for the segments along the Xianshuihe-Xiaojiang fault zone.We obtained 11 sites of single-segment or multi-segment rupturing risk.We also provided these potential events conditional probabilities in the next 30 years.For the 11 potential earthquakes,we calculated the property loss of residential buildings in the ground motion field.The most significant property loss is CNY 7.65 billion caused by the single-segment rupturing of the F19 segment on the Anninghe fault.We applied the deep learning neural network method in predicting the number of casualties for the potential earthquakes,showing that the most significant event is the multi-segment rupturing of the F29 and F30 segments on the Anninghe fault with the predicted death number of 279-317.We also evaluated the probabilities of earthquake landslides after the potential earthquakes.The results show that areas with intense compressional tectonic stress are highly unstable and prone to earthquake induced landslides,including the southern section of the Yuke fault,the southern section of the Xianshuihe fault,and the conjugated area between the southern section of the Daliangshan fault and the Lianfeng fault.These areas have a considerable number of earthquake landslides with probabilities>10%.The methodology and results will give us a new effective way of applying active fault data in earthquake hazard and risk analysis and provide a scientific path for earthquake prevention,disaster reduction,and emergency rescue preparation.
基金Chinese Joint Seismological Science Foundation.Contribution! No. 2000A005Institute of Crustal Dynamics, China Seismological
文摘From the results of researches of active faults in resent years, a correlation analysis between segments of the faults according to surface ruptures in nine historical strong earthquakes occurring in downfaulted system and active structures around Ordos block is conducted in paper. The result shows that there is a good correlation between them, except few individual data that have more uncertain parameters. It shows that intensity and segments of surface ruptures in these strong earthquakes are intrinsically related with the active structures. These strong earthquakes produced stable and unstable rupture boundaries of characteristic-earthquake type and successive occurrence of strong earthquakes on the different boundary faults in the same tectonic unit.
文摘On the basis of the recent geological surveys and the relevant studies of the Xianshuihe fault zone, this paper analyzes the seismogenic mechanism of some faults and characteristic morphology on the fault zone by the boundary element method and discusses the fault segmentation and the related distribution of the earthquake ruptures. The main conclusions are: For the first order segmentation, the Xianshuihe fault zone can be divided into three major segments (the northwestern Luhuo-Qianning segment, the middle linking fracture region and the southeastern Kangding segment). Among them, the differences are not only in geometry and structure, but also in mechanical property and dynamics. Some of the characteristic morphologies on the Xianshuihe fault zone reflect the effects in cumulative deformation due to long-term fault movement, and reveal the fault segmentation in different orders. Such morphologies control, to some extent, the developments and the distributions of the earthquake ruptures on the fault zone.
基金The research was sponsored bythe keyresearch project entitled"Seismic Safety Evaluation and Structural Earthquake Resistance"under the 10th Five-Year Program of the ChinaEarthquake Administration the Joint Earthquake Science Foundation of China (0101302) Contribution number :2005A001 ,the Institute of Crustal Dynamics ,CEA.
文摘Segmentation of the thrust fault zone is a basic problem for earthquake hazard evaluation. The Yingjing-Mabian-Yanjin thrust fault zone is an important seismic belt NW-trending in the southeast margin of the Qinghal-Xizang （Tibet） plateau. The longitudinal faults in the thrust zone are mainly of the thrust slipping type. The late Quaternary motion modes and displacement rates are quite different from north to south. Investigation on valleys across the fault shows that the transverse faults are mainly of dextral strike-slipping type with a bit dip displacement. Based on their connections with the longitudinal faults, three types of transverse faults are generalized, namely： the separate fault, the transform fault and the tear fault, and their functions in the segmentation of the thrust fault zone are compared. As the result, the Yingjing-Mabian-Yanjin thrust fault zone is divided into three segments, and earthquakes occurring in these three segments are compared. The tri-section of the Yingjing-Mabian-Yanjin thrust fault zone identified by transverse fault types reflects, on the one hand, the differences in slip rate, earthquake magnitude and pace from each segment, and the coherence of earthquake rupturing pace on the other hand. It demonstrates that the transverse faults control the segmentation to a certain degree, and each type of the transverse faults plays a different role.
文摘To investigate the recurrence behaviors of segment-rupturing eathquakes on active faults of the Chinese mainland, thispaper analyzes quantitatively earthquake history of 19 fault segments based on earthquake dam of multi-cyclerecurrences. The result shows that, for these fault segments, eanhquake recurring at previous locations is mainlycharacterized by both quasi-periodic (in a ratio of about) and time-predictable (in a ratio of about) behaviors.For the first behavior. intrinsic uncertainty of recurrence interval accounts for 0. 15-0.40 of the average interval, andmagnitudes of event vary from cycle to cycle within the range of the mean magnitUde t0.5. For the second behavior,intrinsic uncertainty of recurrence interval ranges mostly from 0. 19 to 0.40 of the average interval, and for successivetwo cycles the maximum change of event magnitudes is as much as 1.7 magnitude-units. In addition, for a few casesthe first behavior coexists along with either the second or the slip-predictable behaviors.
基金supported by the National Natural Sciences Foundation of China(Grants No.41202156 and 41330211)China Geological Survey(Grants No.12120115026901 and 12120115027001)the Institute of Geology,CAGS(Grant No.J1520)
文摘As one of the longest strike-slip fault in Asia,the Altyn Tagh Fault（ATF）defines the northern boundary of the Tibetan Plateau and plays a significant role inaccommodating the deformation resulting from the IndiaAsia convergence.
基金financially supported by Guangdong Provincial Science and Technology Plan Projects(20178030314082)General Project of National Natural Science Foundation of China (41676057)National Science and Technology Support Program (2015BAK18B01)
文摘By systemic processing, comprehensive analysis, and interpretation of gravity data, we confirmed the existence of the west segment of the coastal fault zone(west of Yangjiang to Beibu Bay) in the coastal region of South China. This showed an apparent high gravity gradient in the NEE direction, and worse linearity and less compactness than that in the Pearl River month. This also revealed a relatively large curvature and a complicated gravity structure. In the finding images processed by the gravity data system, each fault was well reflected and primarily characterized by isolines or thick black stripes with a cutting depth greater than 30 km. Though mutually cut by NW-trending and NE-trending faults, the apparent NEE stripe-shaped structure of the west segment of the coastal fault zone remained unchanged,with good continuity and an activity strength higher than that of NW and NE-trending faults. Moreover,we determined that the west segment of the coastal fault zone is the major seismogenic structure responsible for strong earthquakes in the coastal region in the border area of Guangdong, Guangxi, and Hainan.
基金Natural Science Foundation of Anhui Province (01045403) and Joint Seismological Science Foundation of China (102038).
文摘By means of differentiation of remote sensing image, field seismo-geological survey, analysis on drilling explora- tion materials, sampling and dating of rock samples, combined with seismicity and microscopic tectonic analysis, this paper studies the recent activity of Chihe segment of the Tanlu fault zone. The result indicates that the Chihe fault segment undergoes the deformation alternately in the mode of stick slip and creep during Late Quaternary, and its recent activity is mainly creep.
基金supported by the Chinese Geological Survey (CGS) (Grant No.1212011120181 & Grant No.1212011120115)a key project of the Natural Science Foundation of China (Grant No.41030317)
文摘This study＇s objective was to investigate the Guguan-Xiangong Fault, which lies in the southern Liupanshan area, through satellite image interpretation and field observations. Guguan- Xiangong Fault is divided into five subsegments; among these, the Badu-Longwei segment has been the most recently active. The geomorphic features of the Badu-Longwei segment are clearly displayed, including multiple high fault scarps with fresh bedrock free faces. There is significant evidence for Holocene activity of the three fault sections, located in Renhuashu, Tianjiagou, and Xinjiecun respectively. The three sections feature distinct episodic deposition and fault scratches. Based on 14C- dating and field observations on the three fault sections, two or more paleoearthquakes across the Badu-Longwei fault segment are ascertained, between 5874±116 and 5430±140 a BP, and after 2037±83 a BP respectively. The Badu-Longwei segment of the Guguan-Xiangong Fault is preliminarily extrapolated as the seismogenic structure of the 600 A.D. Qin-Long earthquake.
基金supported by the National Natural Science Foundation of China(grant No.41302159)
文摘Objective The uplift process and uplift mechanism of the Tibetan Plateau has been a research focus among geologists in recent years. This work put emphasis on the Cenozoic exhumation histories of the blocks bounded by the major faults at the central segment of the Longmenshan thrust belt, and the vertical faulting history, including the starting time and the total vertical displacement, of the major faults. Then we quantitatively established a complete active process for the central segment of the Longmenshan thrust belt, combining with the previous geophysical data in the deep and geologcial data. This study is critical for deeply and completely understanding the Cenozoic uplift history of the Longmenshan, and also provides thermochronology constraints to the different models for the uplift of the eastern margin of the Tibetan Plateau.
文摘In this study, Landsat 5 Thematic Mapper (TM) and SPOT HRV Panchromatic data were analysed to determine the geometry of an active fault segment (the Ganos segment) in Gazikoy-Saros region, west of Marmara Sea, Turkey. Gazikoy-Saros/Ganos segment is a part of North Anatolian Fault Zone (NAFZ). North-Anatolian fault is considered to be one of the most important active strike-slip faults in the world. Thus far in relevant researches based on Gazikoy-Saros segment a single straight fault line representation is used on the fault descriptive geological maps. This study, with the aid of enhanced remotely sensed data aims to reveal the linear details of the NAFZ fault segment, which subsequently were superposed with a Digital Elevation Model (DEM) data. Respectively, using these data the surface geometry expression of Gazikoy-Saros fault segment was detailed and remapped. According to the results of the analysis two small releasing steps were identified on this segment. The first one is situated between Mürseli and Güzelkoy villages, and the second one is between Mürseli and Yorguc villages. In addition to this, it is found that the fault strike bends approximately 7° further to in south-eastern (SE) direction between Yenikoy and Sofular villages. This angular change was defined with the advantage of multi-angular viewing capability of the multi-satellite sensors and DEM data. The newly generated surface geometry expression of Ganos segment was compared with Global Positioning System (GPS) velocity vectors.
基金sponsored by the Director Fund of Institute of Seismology,China Earthquake Administration(IS201526240)Data Sharing Special Project of the Ministry of Science and Technology,the People's Republic of China(IS20135065)
文摘In order to obtain deformation parameters in the south segment of Longmenshan fault zone,Euler datum transformation and the least square collocation for data interpolation and smoothing are used to process GPS displacement time series data in the south segment of Longmenshan fault zone,and the rigid and elastic-plastic block motion model is used to calculate the strain parameters in each subarea. Conjoint analysis of displacement,velocity of each station and strain parameters of each subarea reveals that the influence of the Wenchuan earthquake on the south segment of Longmenshan fault zone increases from southeast to northwest,causing a highest deformation rate 6 times the background value and heightening the influence of the hidden faults on the difference of the earth surface along its two sides,which leads to the seismic risk of the southern segment increasing from north to south. The comparison of seismic risk among subareas based on the tectonic and seismicity background indicates that the most dangerous area is on the southeast of Longmenshan faults,and the background strain accumulation and the promoting effect of the Wenchuan earthquake advanced the occurrence of Lushan earthquake and the sinistral strike-slip on the rupture plane. The Wenchuan earthquake also caused a slight two-year long continuous strain release in the south segment of Xianshuihe fault,but the influence is far less than the effect of the compressive strain caused by the Sichuan-Yunnan block.
