Active Tectonic Movement Research Articles

Dynamic Characteristics of the Long Runout Rock‐ice Avalanche at High Altitude—A Case from the Zelongnong Basin, Eastern Himalayan Syntaxis, China

AbstractRock‐ice avalanches have frequently occurred in the Eastern Himalayan Syntaxis region due to climate change and active tectonic movements. These events commonly trigger catastrophic geohazard chains, including debris flows, river blockages, and floods. This study focuses on the Zelongnong Basin, analyzing the geomorphic and dynamic characteristics of high‐altitude disasters. The basin exhibits typical vertical zonation, with disaster sources initiating at elevations exceeding 4000 m and runout distances reaching up to 10 km. The disaster chain movement involves complex dynamic effects, including impact disintegration, soil‐rock mixture arching, dynamic erosion, and debris deposition, enhancing understanding of the flow behavior and dynamic characteristics of rock‐ice avalanches. The presence of ice significantly increases mobility due to lubrication and frictional melting. In the disaster event of September 10, 2020, the maximum flow velocity and thickness reached 40 m/s and 43 m, respectively. Furthermore, continuous deformation of the Zelongnong glacier moraine was observed, with maximum cumulative deformations of 44.68 m in the distance direction and 25.96 m in the azimuth direction from March 25, 2022, to August 25, 2022. In the future, the risk of rock‐ice avalanches in the Eastern Himalayan Syntaxis region will remain extremely high, necessitating a focus on early warning and risk mitigation strategies for such basin disasters.

Tectonic ledges at the Ladoga Lake bottom

For the past few years, the Institute of Limnology of the Russian Academy of Sciences has been conducting geological and geomorphological studies of the bottom of Lake Ladoga. Starting from 2018, underwater photo and video cameras developed at the Institute began to be used in these studies. The use of this new research tool led to the discovery of a number of new facts about the structure of the bottom of Lake Ladoga. In particular, at the bottom of the northern part of Lake Ladoga, three subvertical ledges were found, composed of bedrock, up to 70–100 meters high. According to a number of features, such as the bedrock composition of rocks, morphology and spatial correspondence to known fault zones, these ledges can be recognized as morphological expressions of tectonic objects – faults of presumably fault type. The absence of visible traces of glacial processing on the bedrock blocks suggests the Holocene age of the formation of these ledges and, accordingly, the existence of modern active tectonic movements in the area of Lake Ladoga.

Study of Earthquake Landslide Hazard by Defining Potential Landslide Thickness Using Excess Topography: A Case Study of the 2014 Ludian Earthquake Area, China

Influenced by the combined effects of crustal uplift and river downcutting, rivers with significant potential energy are often found in high mountain and canyon areas. Due to the active tectonic movements that these areas have experienced or are currently experiencing, geological hazards frequently occur on the mountains flanking the rivers. Therefore, evaluating the susceptibility and risk of earthquake landslides in river segments of these high mountain and canyon areas is of great importance for disaster prevention and mitigation, as well as for the safe construction and operation of hydropower stations. Currently, a major challenge in the study of landslide susceptibility and hazard is determining the thickness of potential landslide bodies. The presence of excess topography reflects the instability of the disrupted slopes, which is also a fundamental cause of landslides. This study takes the example of the Ludian earthquake in 2014, focusing on the IX and VIII intensity zones, to extract the excess topography in the study area and analyze its correlation with seismic landslides. The correlation between the critical acceleration value and the excess topography was validated using the Spearman’s rank correlation coefficient, resulting in a correlation coefficient of −0.771. This indicates a strong negative correlation between the excess topography and critical acceleration, with significant relevance. The landslide susceptibility distribution obtained by setting the potential landslide thickness based on the excess topography and proportion coefficient showed an ROC curve analysis AUC value of 0.829. This is higher than the AUC value of 0.755 for the landslide susceptibility result using a uniform potential landslide thickness of 3 m, indicating the higher model evaluation accuracy of this approach. Earthquake landslide hazard predictions for rapid post-earthquake assessments and earthquake landslide hazard zoning for pre-earthquake planning were made using actual seismic ground motion and a 2% exceedance probability in 50 years, respectively. Comparing these with the 10,559 coseismic landslides triggered by the Ludian earthquake and evaluating the seismic landslide development rate, the results were found to be consistent with reality. The improved model better reflects the control of excess topography and rock mechanics properties on the development of earthquake landslide hazards on high steep slopes. Identifying high-risk seismic landslide areas through this method and taking corresponding preventive and protective measures can help plan and construct safer hydropower and other infrastructure, thereby enhancing their disaster resistance.

Application of morphotectonic indices for assessing active tectonics: A case study of Acheron river basin

Rivers tend to alter the morphology of their bed and valley as a response to changes in their base level. The study of a drainage basin's tectonic activeness is very important. But especially in areas where rates of vertical tectonic movements are scarce, the morphometric analysis can be proved to be a very accurate method for assessing the effects of neotectonic movements on a drainage network. This method is easy to apply, as it does not require a lot of data. This study concerns the drainage basin of Acheron river in Epirus, Greece. In order to assess of river's response to active tectonic movements, a morphometric analysis was conducted, using a digital elevation model (DEM). Seven morphometric parametres and five geomorphic indices were calculated for the entire basin, as well as 9 sub-basins. Subsequently, each sub-basin was categorised into three categories regarding tectonic activeness (high-medium-low) for each index individually. The relative active tectonics index was also calculated, as the average of the aforementioned morphometric parametres and geomorphic indices. Based on that, each sub-basin was categorised into three categories regarding the overall tectonic activeness (low-medium-high). These results were compared with the drainage pattern and field observations, so as to gain insights on the tectonic activeness of the sub-basins and the entire basin of Acheron.

Mixed siliciclastic-carbonate-tuffaceous sedimentation in a rift lacustrine basin: A case study of the Lower Cretaceous Jiufotang Formation in the Luxi sag, Songliao basin

The Lower Cretaceous Jiufotang Formation lacustrine successions in the rift Luxi sag, Songliao Basin are characterized by mixed siliciclastic-carbonate-tuffaceous and organic-rich deposits. Ten facies were recognized and were formed in fan delta, delta, littoral-sublittoral lacustrine and deep lacustrine environments. A depositional sequence characterized by significant changes in facies and lake regime has been defined, and is divided into lowstand systems tract (LST), transgressive systems tract (TST), and highstand systems tract (HST) that are separated by sequence boundaries, initial flooding surfaces, and maximum flooding surfaces, respectively. During the LST, the delta and fan delta deposits covered the marginal area and extended into littoral-sublittoral lacustrine and deep lacustrine environments, respectively. During the TST, the areas of delta and fan delta decreased and lake areas increased, and the carbonate-dominated shoals and mixed siliciclastic-carbonate shorelines occupied the edge of the Majiapu highland belt. During the HST, the lake areas further expanded, and the fan delta deposits extended into deep lacustrine environments and formed deposits of underflows and turbidites. A depositional model in the rift lacustrine Luxi sag is proposed, incorporating the effects of tectonics and sediment supply, climate and carbonate production, hydrodynamic conditions, and lake-level fluctuations. During the LST, the active tectonic movement, high input of siliciclastic sediments, and subaerial volcanic eruptions resulted in the wide distribution of mixed siliciclastic-tuffaceous sedimentation. During the TST, the brackish lake water controlled by periodic dry and hot climate facilitated the carbonate deposition in shallow water, and tractional currents onto the lake shore carried sediments to form the mixed siliciclastic-carbonate-tuffaceous facies. During the HST, more humid climate and increased runoff allowed formation of widely distributed, mostly oil shale-rich deposits, and the gravity flows carried the sediments into the deeper part of basin to form the mixed siliciclastic-carbonate-tuffaceous facies. The depositional model of mixed deposits in this rift lacustrine basin has been proposed here in order to encourage comparison with other similar basins.

Active faults studies in Delhi and national capital region (NCR): Inferences from satellite data and field investigations

In recent years, the National Capital Region (NCR) of Delhi has experienced several earthquakes ranging in magnitude from 1.0 to 6.7. According to the last 50 years of earthquake data, the majority of earthquakes in the NCR have occurred near the Mahendragarh Dehradun Fault (MDF) and the Sohna Fault (SF). The region is bounded by a number of subsurface Ridges, Faults, and Lineaments, which are also influenced by the active plate boundary of the Indian and Eurasian plates. Active fault mapping is critical for the precise identification and marking of active fault traces in the NCR area for a precise seismic hazard assessment. We used high resolution Cartosat-1 stereopair data obtained from NRSC, Hyderabad, and Anaglyph (A 3D representation of the surface) and DEM prepared with ENVI software to map the active faults. We identified 12 sites in the NCR region based on satellite data interpretation, primarily along the MDF and Sohna Fault and their extensions. The presence of tectono-geomorphic markers along the MDF and Sohna Fault, such as warped surfaces indicative of fault scarps, stream offsets, gully erosion, and sag ponds, suggests active tectonic movement along these faults, most likely in the recent geological past. We believe the MDF is a right-lateral strike-slip fault with a compressional component on the western side and an extensional component on the eastern side. It acts as a segment boundary between compressional and extensional boundaries. We also identified the right lateral Nuh-Jhirka fault (NJF), which can be the Sohna Fault’s southern extension from Nuh to Jhirka. The western limb of the Delhi Mega fold has also seen a few right-lateral strike-slip movements that have extended up to the eastern bank of the Yamuna River, where the river reflects the base-level change and tight meandering on its upward side and a straight pattern on its downward side. This fault is known as the Delhi Fault (DF). The findings are preliminary, and further research would be required to create a detailed active fault map of the Delhi-NCR region to conduct a precise Seismic Hazard Assessment (SHA) of the region.

Critical area identification and dynamic process simulation for landslide hazard chain formation in the upstream Jinsha River

The upper reaches of the Jinsha River, with their complex terrain and active tectonic movements, are vulnerable to landslide-induced hazard chain events, which endanger the safety of residents and infrastructure construction. Based on the analysis of the development background of the hazard chain in the upstream area of the Jinsha River, five factors, including the lithology, distance to faults, distance to rivers, peak ground acceleration, and slope degree, were selected to identify the critical landslide-prone areas. Principal component and grey correlation analyses were then conducted to determine the contributions of these different factors. Based on ArcGIS, the study zone was categorized into five classes of landslide susceptibility: very high, high, moderate, low, and very low. The identification of the critical target areas for landslide hazard chain formation showed satisfactory accuracy. The very high- and high-susceptibility areas are concentrated along the Jinsha River. The dynamic process of a typical landslide in a very high-susceptibility area was numerically simulated using OpenLISEM. The high-precision Baige landslide data of the study area were used to calibrate the practicality of the input mass parameters, including cohesion, internal friction angle, D50, and D90. The movement and accumulation processes of a typical landslide were then numerically simulated with the verified data. The entire landslide accumulation covers an area of 0.45 km2, with a length of 1,600 m and a width of 270 m. Thus, the OpenLISEM model, which combines mass, topography, and landcover parameters, is feasible for the numerical simulation of landslide dynamic processes. The prediction of the dynamic processes and accumulation morphology of landslides can provide a reference for the formation processes and mechanisms of the landslide-induced hazard chain in the upper Jinsha River.

Design of offshore gas pipelines against active tectonic fault movement

Active tectonic faults impose permanent ground actions on offshore gas pipelines that threaten their safety and service life. The seismic fault movement deforms the pipeline and causes excess strains due to bending, along with axial compressive or tensile forces depending on the fault type. This may lead to buckling, severe cross-sectional distortion and even rupture. The assessment of an offshore pipeline crossing active faults considers the estimation of the potential fault displacement, the structural response of the pipeline, and the limit-state capacity. This paper explores the design options for improving the capacity of partially embedded offshore pipelines to tolerate fault differential displacement using equations that are fitted to the results of finite element simulations and allow the prediction of the critical co-seismic fault displacement, i.e. the value of fault displacement that leads to various forms of pipeline failure. Considering all the types of faults, the influence of the parameters affecting the performance of an offshore pipeline subjected to active seismic fault rupture is quantified and discussed. The proposed equations could be used as guidance in the preliminary route design of future medium-diameter offshore pipelines and in the assessment of the vulnerability of existing ones. An illustrative example is also presented to demonstrate the application of the proposed equations.

Developmental Mechanism of Rainfall-Induced Ground Fissures in the Kenya Rift Valley

Active tectonic movement and frequent ground fissure disasters occur in the Kenya Rift Valley. Ground fissures are often exposed to the ground surface after rainfall, resulting in disasters and huge economic losses. We conducted a field geological survey and exploratory trenching in order to identify the developmental characteristics of ground fissures in the Kenya Rift Valley. The ground fissures were found to be connected with concealed bedrock fissures, which is a typical characteristic of tectonic ground fissures. From the perspective of regional tectonic stress and plate movement, we investigated the causes of hidden bedrock cracks and conducted a finite element numerical simulation to study the rainfall infiltration process in the presence of hidden bedrock fractures. The results showed that the fractures in the concealed bedrock are controlled by regional tectonic stress and a northwest-trending basement tectonic shear zone. The most intense rainfall infiltration erosion occurs in concealed cracks, where the settlement induced by rainfall is also greatest. Therefore, rainfall erosion is an important factor driving the expansion of ground fissures towards surface fractures. The results of this study provide a theoretical scientific basis for disaster reduction and the prevention of ground fissures in the Kenya Rift Valley.

On the Issues of Spatial Modeling of Non-Standard Profiles by the Example of Electromagnetic Emission Measurement Data

This paper examines the possibility of the spatial modelling of the Earth’s natural pulsed-electromagnetic-field measured values, which form a closed profile without the data inside. This geophysical method allows us to map active tectonic movement which breaches the integrity of pipes. During the experiment, 4.5 km of profiles were measured in the Admiralteysky district of St. Petersburg, Russia. Regular electromotive force (EMF) values and anomalous EMF values were obtained, ranging from 0 to 900 µV and above 900 µV, respectively. The anomalous values are associated with tectonic faults in the bedrock. The data obtained are characterized by complex spatial anisotropy associated with the development of two groups of tectonic faults of different orientations. The authors have considered the problems of the spatial modeling of the data obtained. The main problems, the solutions to which should allow the obtaining of adequate models, have been identified. Based on the analysis of the measurement results, geological features of the studied areas, as well as variography, the following possible solutions were proposed: changing the measurement technique; dividing the data array according to the main directions of anisotropy; the need to introduce additional correction coefficients. The problem revealed in this article requires further research on the basis of the obtained results, which will reduce the cost and timing of such studies, and, as a result, give an opportunity to take into account active tectonic disturbances during the construction and scheduled maintenance of underground utilities, which is especially important within the framework of the concept of sustainable development.

Permian and Triassic paleosols in the fluvial-lacustrine record of the central Pyrenees Basin, Spain: A stratigraphic tool for interpreting syn-tectonic sedimentary evolution and paleoclimate

Paleosols as stratigraphic tools are an established approach in the study of continental basins and offer information on the complex interplay between the factors that control the filling of basins, as the accommodation, deposition, erosion, and climate, which exerts a great influence on the supply rate of sediment and water from the sources to the basin. They are also useful to describe alternating phases of active tectonic movements and quiescence. In highly deformed basins, the differentiation between lithostratigraphic units with very similar facies but different ages may be problematic. In these cases, paleosols are a good distinguishing criterion because they are very sensitive to both climatic and topographic changes and distinct types of paleosols are expected in units deposited under different conditions. On the southern border of the Pyrenees, early Permian terrestrial red-beds were deposited under a transtensive-extensive tectonic context in isolated strike-slip sub-basins affected by syn-sedimentary tectonic activity, which generated internal unconformities of different orders. A generalized extensive tectonics was developed from middle Permian onwards, allowing the incursion of the first Tethys transgression in the Pyrenean Basin during the Middle Triassic. Subsequent Alpine tectonic inversion greatly affected the configuration of the basins, adding to their complexity. In this work, the paleosols observed in the field are described, classified, and interpreted in order to study the link between pedogenesis and the evolution of the landscape under changing tectonic and palaeoclimatic conditions. Grouped into palaeocatenas, the lateral variation of pedotypes across the landscape is used to interpret topography and water table variations, which was explained by variations in climate, available accommodation space, and sedimentary supply. The study of hydrological and climatic conditions was complemented by the identification of the mineralogical composition of the parent material and δ13 C and δ18 O isotopic signatures from the inorganic pedogenic carbonate of paleosols and lacustrine limestones. These continental basins of the Pyrenees were strongly disconnected during the Permian and characterized by several periods of non-deposition and erosion. The results provided herein improve our knowledge of the tectonic and palaeoclimatic conditions of this near equator area of the westernmost peri-Tethys domain during the first stages of the Pangea break-up.

RISK ANALYSIS OF MAJOR ENGINEERING GEOLOGICAL HAZARDS FOR SICHUAN-TIBET RAILWAY IN THE PHASE OF FEASIBILITY STUDY

The Sichuan-Tibet Railway is the most challenging railway project ever in the world. The project region is characterized by various adverse geological conditions including active tectonic movement, intensive mega faults, abrupt topographic relief and frequent geological disasters. Therefore, the construction of this project is challenged by complex geological disaster risks from both ground surface and underground. This study comprehensively and quantitatively analyzes the ground surface and underground geological risks along the Sichuan-Tibet Railway, and further evaluates their consequential influences on the project so as to support its feasibility study. The risk analysis utilizes abundant spatial-temporal data, and various approaches including three-dimensional structure modeling, numerical modeling, statistical modeling, dynamic modeling, time series modeling and spatial distribution modeling. The results show that there are three areas concentrated with high ground surface geological hazards risk along the Sichuan-Tibet railway, namely the Xianshuihe fault zone, the Jinshajiang fault zone and the eastern Himalayan syntaxis area. However, ground surface engineering risks of this project are significantly reduced, because its underground tunnels are over 80% of the total railway line length. The universal quantitative risk assessment models are developed for major underground engineering geological risks, including fault activities, rock bursts and large deformations. For several major tunnels such as the Yigong tunnel, risks of typical individual underground geological hazards(e.g. rock burst and large deformation) as well as the integrated risk, are quantitatively evaluated. The results show that both surface and subsurface engineering risks are significant and can threaten the safety of project. This study provides a scientific and technical support for the feasibility study of the Sichuan-Tibet Railway, and is also expected to be a reference for major engineering geological risk control for similar line engineering projects around the world.

China starts the world’s hardest “Sky-High Road” project: Challenges and countermeasures for Sichuan-Tibet railway

Abstract The Sichuan-Tibet railway of China starts from the western Sichuan basin and subsequently runs across the “Roof of the World”-Tibet plateau, which is dubbed “Sky-high road”. However, several challenges, including the world's most remarkable topographic relief, active tectonic movement, frequent mountain hazards and vulnerable ecological environment, exert significant effects on railway construction and operation. This epic railway project, thus, has always been the world’s toughest problem. Here, we provide an overview of the existing challenges and discuss the relevant countermeasures. We highlight that an intelligent monitoring and early warning system is the top priority for eliminating the high hazard risks threatening the railway. Also, new materials and building structures are indispensable for railway surviving from active fault dislocation and earthquakes. For protecting the ecological environment, we are head for realizing humankind-nature-railway harmonious intergrowth. Completing the Sichuan-Tibet railway will promote the scientific and technological development of China and even the world.

Evaluating the seismic hazard in the Kachchh Region, western India using the river gradient length anomaly technique

In the present study, we assess seismic hazard potential and surface deformation pattern along and across the strike of major active faults in the intra-plate Kachchh Rift Basin (KRB). Towards this, we adopted river Gradient Length Anomaly (GLA) technique, which detects recent tectonic deformation along a river profile on local and regional scales. The major deviations along the river profile can be correlated with exogenic (erosion/sedimentation/anthropogenic) and endogenic (active tectonic movement) processes. We analysed 130 river profiles for GL anomalies, over an area of ~26,700 km2 in the KRB to identify possible locations that have undergone active tectonic deformation associated with the fault movement. The acquired results show that the higher magnitude negative GL anomalies (uplift) are observed proximal to the fault zones. Our estimates reveal that, around 13% of the study area falls under high tectonically active zone, around 27% of the area falls under moderately active zone, while 60% of the area shows very low or negligible tectonic activity. The estimated results of the GL anomalies are compared with the existing double-difference tomograms, to understand the role of subsurface fault dynamics on the GL anomalies. Furthermore, the results of GLA are correlated with the existing results of the peak ground acceleration (PGA) values of the basin, in order to obtain the precise information regarding surface deformation and site-specific ground acceleration for accurate assessment of seismic hazard.

Late Paleozoic Tectonic Evolution of the Paleo‐Asian Ocean in the Northern Alxa Block (NW China)

AbstractThe northern Alxa Block occupies a key position in the southern margin of the Central Asian Orogenic Belt (CAOB) and records late Paleozoic subduction and closure processes of the Paleo‐Asian Ocean (PAO). However, there are still controversies regarding the timing and location of the final closure of the PAO. This study presents structural deformation data and geochronological and geochemical data for Permian volcanic rocks, as well as detrital zircon provenance analysis of Permian sedimentary rocks along the Nuoergong‐Langshan Zone (NLZ) in the northern Alxa Block. During the early to middle Permian, the PAO lithospheric slab subducted beneath the northern Alxa Block, rendering a continental volcanic arc in the NLZ and also giving rise to extensive folding, thrusting, and crustal thickening. The crustal thickening in the NLZ may trigger the early Permian magmatic flare‐up that constructed much of the continental arc plutons. In the middle to late Permian, a retroarc foreland basin was formed, within which the Dahongshan Formation deposited. Significant active tectonic movements led to regional unconformity occurring during this period. A large‐scale dextral ductile shear deformation in the NLZ resulting from the lateral extrusion of the thickened crust after the terminal amalgamation of the southern CAOB was constrained between 272 and 249 Ma, suggesting a late Permian tectonic transition from compression to transpression. Combining these findings with published data, we suggest that the final consumption of the PAO occurred in the late Permian, probably along the Enger Us suture zone in the northern margin Alxa Block.

Quantitative Geomorphic Approach for Identifying Active Deformation in the Foreland Region of Central Indo-Nepal Himalaya

Globally the remote sensing and geomorphometric analysis are frequently used for the assessment of tectonic activity. We used satellite-driven DEM data to analyze regional scale fluvial landform development in the parts of the central section of the Indo-Nepal Himalayan mountain chain, which is attributed the active deformation along the strike of major thrust. This deformation is accompanied by coexisting river incision and base-level fall along the longitudinal river course. These anomalies are obtained through conventional geomorphic parameters namely, stream-gradient index (SL), and steepness index (Ks) along with a new method called river Gradient Length Anomaly (GLA) analysis. GLA is a lied to deduct surface uplift and subsidence at the intersection between drainage basin and active thrusts. The deviations (offset) occurred along the river course are attributed to long-term active tectonic movement along thrust/fault or because of erosion/sedimentation processes. We analyzed 16 south-flowing rivers (e.g. Sarda, Kauriala, Girwa, and Babai), across the major Himalayan thrusts such as Main Boundary Thrust (MBT), Ramgarh Thrust (RT) and Himalayan Frontal Fault (HFT). The computed values of SL along the longitudinal course of these rivers range between 0.9‒4153 and Ks ranges from 0.1 to 173. The anomalous rise of SL and Ks values close to the major thrust points toward ongoing tectonics in the basin. The estimated results of fault parameters show that the horizontal shortening is higher than the vertical uplift. The empirical relationship of slip rate along the fault segments is estimated as 1.21, 2.65 and 1.084 mm/y respectively. Based on fault parameter, and abnormal GLA, SL and Ks analysis, and slip rate, a new E‒W oriented active fault structure have been inferred, which passes through the Beldandi, Bilsan, Bachua, Nandgaon, Dhagadhi Surat Nagar, and Bhagwanpur locations. The combined results of the present investigation can be used for evaluation of seismic hazard in the central section of Indo‒Nepal Himalayan front.

The background noise level of vertical pendulum tiltmeter in China

By using the observation data of the vertical pendulum tiltmeter in China, the influence of different sampling rates on the results of power spectral density is studied, and the background noise level of the seismic frequency band (200–600 s) of different stations and different types of instruments is emphatically analyzed. The conclusions are as follows: 1. The results of both single station and national statistics show that the noise levels of the two types of pendulum tiltmeter equal in the seismic frequency band; 2. There is no obvious regularity in the regional distribution, due to the influence of ocean and active tectonic movement, the noise levels of some stations in coastal areas are relatively high; 3. The curves of high noise level instrument are generally not smooth and burr-prone. Except for some stations affected by the ocean, they are mostly caused by the observation environment or the instrument itself.

The global and local robustness analysis in geodetic networks

The geodetic networks should be able to detect the possible earth crust movements caused by active tectonic movements in Turkey. Geodetic networks should also be able to determine the crust movements accurately as well as provide precision and reliability requests. The capacity of geodetic networks to determine the crustal movements can be determined by sensitivity analysis. Robustness analysis consists of strengthening internal reliability analysis with strain techniques. Robustness is defined as the deformation strength induced by the maximum undetectable errors with the internal reliability analysis. The robustness of a geodetic network is determined by the global initial condition, which aims at minimizing the total displacement value in the network. In this study, the local initial condition that aims to minimize the total displacement value at the uniform polyhedron, which consists of observations from each station points. The displacement values obtained according to the local and the global initial conditions are compared with threshold values. The results have also been interpreted.

Interpreting deformation results of geodetic network points using the strain models based on different estimation methods

Geodetic Networks designed as Deformation Networks or Continuous Networks are observed in different epochs/ sessions and evaluated as a function of time. Those can be design as global GNSS networks for aim monitoring active tectonic movements or as regional densification geodetic and deformation networks for monitoring local earthquakes and surface movements. The areas covered geodetic networks are assumed as any surface on ellipsoid or sphere. Characteristics of surfaces are analyzed with Geometric Strain Models using deformation data on surface points. In this case, effect rates on geodetic network area are determined from local surface movements or regional active earthquakes and interpreted as experimental. On the other hand, undetermined outliers by model hypothesis test affect coordinate unknowns separately. Outliers cause deformations in certain magnitude on networks points. Therefore, network points strain in different rates and directions. Query of maximum affects caused by these strain rates is a referenced reliability method called "Robustness Analysis in Geodetic Networks”. Mentioned strain rates are modelled by various estimation methods. Thus, deformation results could be interpreted together by the obtained strain components and deformation vector. In this paper, possible strain components belonging to network points are determined with methods of L1 Norm, Least Median Squares (LMS) and Least Squares Estimation (LSE). These estimation methods are tested on KOUSAGA (Kocaeli University Permanent GPS Network). Strain components are estimated by use polyhedrons covered by network points. Obtained results are compared and analyzed according to weakness and strengths of proposed estimation methods.

Influence of tectonic uplift of the Qinling Mountains on the paleoclimatic environment of surrounding areas: Insights from loess–paleosol sequences, Weihe Basin, central China

The southern edge of the Chinese Loess Plateau affected by the stepwise uplift of the Qinling Mountains is a transitional climatic area between the different climatic environments and sedimentary characteristics to the north and south sides of the Qinling Mountains. The study of different Quaternary loess deposits in this region is conducive to improving our understanding of the micro-scale climatic effects of tectonic developments. Here, we use a series of experimental methods on a well-preserved loess–paleosol sequence in the South Jingyang Plateau to obtain proxy data, including grain-size, magnetic susceptibility, loss on ignition, and geochemical elemental. Changes in grain-size, magnetic susceptibility and loss on ignition indicate that the East Asian monsoon has undergone significant changes due to the continued global cooling and mid-Pleistocene climate transition during the deposition process of XSD loess, i.e., the intensities of the winter and summer monsoons were simultaneously enhanced. Elemental correlations and factor analysis indicate the sedimentary environment and provenance of the deposits, while elemental enrichment and element ratios, including Si/Ti, Al/Ti, Rb/Sr and Zr/Rb, are consistent with changes in the intensity of pedogenic and of the East Asian monsoon as reflected by climate proxies, illustrating that XRF core scanning analysis technology has great potential in the field of Quaternary environmental changes of loess. Furthermore, the stepwise uplift of the Qinling Mountains, which has blocked the winter and summer monsoons to a certain extent, has had a significant impact on the relative degree of loess accumulation and pedogenic in the northern piedmont, southern piedmont and intermontane basin of the Qinling Mountains and also appears to have promoted settlement by early humans. Hence, the study of paleoclimate in areas of active tectonic movement has the potential to promote our understanding of micro-scale climate change in this region in the future.