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Glacial Lake Outburst Flood (GLOF) events, particularly prevalent in Asia's High Mountain regions, pose a significant threat to downstream regions. However, limited understanding of triggering mechanisms and inadequate observations pose significant barriers for early warnings of impending GLOFs. The 2018 Nyalam GLOF event in southern Tibet offers a valuable opportunity for retrospective analysis. By combining optical and radar remote sensing images, meteorological data, and seismicity catalogs, we examined the spatiotemporal evolution, triggering factors, and the outburst mechanism of this event. Our analysis reveals a progressive retreat of 400–800 m for the parent glaciers between 1991 and 2018, increasing the runoff areas at glacier termini by 167% from 2015 to 2018 and contributing abundant meltwater to the glacial lake. In contrast, the lake size shrunk, potentially due to a weakening moraine dam confirmed by SAR interferometry, which detected continuous subsidence with a maximum line-of-sight (LOS) rate of ~120 mm/a over the preceding ~2.5 years. Additionally, temperature and precipitation in 2018 exceeded the prior decade's average. Notably, no major earthquakes preceded the event. Based on these observations, we propose a likely joint mechanism involving high temperatures, heavy precipitation, and dam instability. An elevated temperature and precipitation accelerated glacial melt, increasing lake water volume and seepage through the moraine dam. This ultimately compromised dam stability and led to its failure between 3 August 2018 and 6 August 2018. Our findings demonstrate the existence of precursory signs for impending GLOFs. By monitoring the spatiotemporal evolution of environmental factors and deformation, it is possible to evaluate glacial lake risk levels. This work contributes to a more comprehensive understanding of GLOF mechanisms and is of significant importance for future glacial lake risk assessments. [ABSTRACT FROM AUTHOR]

On 4 October 2023, a glacier lake outburst flood (GLOF) occurred at South Lhonak Lake in the northwest of Sikkim, India, posing a severe threat to downstream lives and property. Given the serious consequences of GLOFs, understanding their triggering factors is urgent. This paper conducts a comprehensive analysis of optical imagery and InSAR deformation results to study changes in the surrounding surface of the glacial lake before and after the GLOF event. To expedite the processing of massive InSAR data, an InSAR processing system based on the SBAS-InSAR data processing flow and the AI Earth cloud platform was developed. Sentinel-1 SAR images spanning from January 2021 to March 2024 were used to calculate surface deformation velocity. The evolution of the lake area and surface variations in the landslide area were observed using optical images. The results reveal a significant deformation area within the moraine encircling the lake before the GLOF, aligning with the area where the landslide ultimately occurred. Further research suggests a certain correlation between InSAR deformation results and multiple factors, such as rainfall, lake area, and slope. We speculate that heavy rainfall triggering landslides in the moraine may have contributed to breaching the moraine dam and causing the GLOF. Although the landslide region is relatively stable overall, the presence of a crack in the toparea of landslide raises concerns about potential secondary landslides. Our study may improve GLOF risk assessment and management, thereby mitigating or preventing their hazards. [ABSTRACT FROM AUTHOR]

Relevant studies have shown that methane gas has a close relationship with seismic activity. The concentration of methane released within a tectonic zone can reflect the intensity status of tectonic activities, which is important for seismic monitoring. In this study, the January 2020 Xinjiang Jiashi earthquake was taken as the research object, and the mature Robust Satellite Technique (RST) algorithm was used to characterize the L3-level methane product data from the hyperspectral sensor, Atmospheric Infrared Sounder (AIRS), installed on the Earth Observing System (EOS) AQUA satellite at the monthly scale, 8-day scale and daily scale. An analysis of the spatial and temporal distribution of methane was carried out for before and after the earthquake based on the 3D structural condition of the gas, and the 3D structural conditions of the 8-day scale were introduced. An 8-day scale 3D structural condition was introduced and migration validation was performed, and the results showed that (1) the seismic methane anomaly-extraction process proposed in this study is feasible; (2) the 3D contour features indicated that the methane anomalies that occurred before the Jiashi earthquake were caused by geogenic emissions; (3) the anomaly-extraction algorithm from this study did not extract the corresponding anomalies in the non-seismic year, which indicated that the anomaly-extraction algorithm of this study has some degree of feasibility; and (4) the migrated validation of the Wenchuan earthquake of May 2008 further suggested that methane anomalies at the time of the Wenchuan earthquake were caused by the earthquake. [ABSTRACT FROM AUTHOR]

Objective. This study aims to evaluate the impact and predictive value of the preoperative NPRI on short-term complications and long-term prognosis in patients undergoing laparoscopic radical surgery for colorectal cCancer (CRC). Methods. A total of 302 eligible CRC patients were included, assessing five inflammation—and nutrition-related markers and various clinical features for their predictive impact on postoperative outcomes. Emphasis was on the novel indicator NPRI to elucidate its prognostic and predictive value for perioperative risks. Results. Multivariate logistic regression analysis identified a history of abdominal surgery, prolonged surgical duration, CEA levels ≥5 ng/mL, and NPRI ≥ 3.94 × 10−2 as independent risk factors for postoperative complications in CRC patients. The Clavien–-Dindo complication grading system highlighted the close association between preoperative NPRI and both common and severe complications. Multivariate analysis also identified a history of abdominal surgery, tumor diameter ≥5 cm, poorly differentiated or undifferentiated tumors, and NPRI ≥ 2.87 × 10−2 as independent risk factors for shortened overall survival (OS). Additionally, a history of abdominal surgery, tumor maximum diameter ≥5 cm, tumor differentiation as poor/undifferentiated, NPRI ≥ 2.87 × 10−2, and TNM Stage III were determined as independent risk factors for shortened disease-free survival (DFS). Survival curve results showed significantly higher 5-year OS and DFS in the low NPRI group compared to the high NPRI group. The incorporation of NPRI into nomograms for OS and DFS, validated through calibration and decision curve analyses, attested to the excellent accuracy and practicality of these models. Conclusion. Preoperative NPRI independently predicts short-term complications and long-term prognosis in patients undergoing laparoscopic colorectal cancer surgery, enhancing predictive accuracy when incorporated into nomograms for patient survival. [ABSTRACT FROM AUTHOR]

Interferometric synthetic aperture radar (InSAR) has been effectively used to monitor surface deformation in a mining area with millimeter-level accuracy. On March 27, 2022, a tailings dam failure occurred in Shanxi Province, China, causing significant damage to surrounding houses, woodland, and roads below the tailings pond. We obtained the surface deformation map of the tailings dam before the catastrophic failure using the InSAR time-series method with a full resolution of Sentinel-1 A. This paper employed a GPU-assisted InSAR processing method for 91 Sentinel-1 images in Interferometric Wide Swath (IW) mode acquired from January 8, 2019, to March 17, 2022. The InSAR results show that during the 25 months preceding the tailings dam failure, Dam-II experienced an average cumulative LOS deformation of nearly 80 mm, while Dam-I experienced a significant deformation of more than 140 mm in the LOS direction. The analysis combining the deformation and rainfall results shows that rainfall significantly affects tailings pond deformation. In general, the deformation evolution has a high correlation with the rainfall annually, but the maximum deformation rate occurs with a delay of about one month compared to the peak rainfall. InSAR technology can significantly improve the monitoring capability of tailings dam failure and other landslide disasters, but it is limited by the observation frequency of the satellite. Thus, improving the temporal resolution of SAR data may assist in predicting tailings dam failure times more accurately. [ABSTRACT FROM AUTHOR]

A Mw 6.6 earthquake struck Menyuan, Qinghai, China, on 7 January 2022. To determine the rupture parameters of this event, the coseismic InSAR deformation fields were mapped and further employed to estimate the focal mechanism. The best-fitting solution emphasized that the 2022 Menyuan earthquake ruptured at the junction of the Tuolaishan fault and the Lenglongling fault. Both rupturing faults were dominated by sinistral strike-slip, and the main slip was concentrated on the shallow part of the rupture plane. The latter was the main rupture segment with a strike of 106° and a dip of 86°. The slip mainly occurred at depths of 0–8 km, and the rupture was exposed at the surface. The maximum slip reached ~3.5 m, which occurred mainly at a depth of 4 km. Joint analysis of the optimal slip model, relocated aftershocks, Coulomb stress change, and field observation suggested that the strain energy in the Tuolaishan fault may not have been fully released and needs further attention. Moreover, the 2022 Mw6.6 Menyuan earthquake caused a significant stress loading effect on the western Tuolaishan fault and eastern Lenglongling fault, which implies that the 2022 event increased the seismic hazard in these regions. [ABSTRACT FROM AUTHOR]

Interferometric synthetic aperture radar (InSAR) technology has the potential to reveal ground surface deformation at high temporal and spatial resolutions, and the InSAR image processing field is progressing toward big data analytics. In this era of big data, as InSAR is usually employed for natural hazard research, processing large InSAR images under time constraints is a fundamental challenge. Graphics processing units (GPUs) have been widely adopted for high-performance computing (HPC) due to their parallel computing capability and low power consumption. Accordingly, we explore the interconnection between InSAR time series processing and GPU hardware for parallel Sentinel-1 InSAR processing. We build a rapid GPU-assisted InSAR processing chain and apply this chain to accelerate the time-consuming optimization steps in Sentinel-1 InSAR processing. This processing chain plays a pivotal role in rapidly calculating InSAR deformation maps using large quantities of Sentinel-1 SAR data and thus can be used in practical applications. We also perform some experiments to demonstrate that the processing chain is appropriate for the deformation monitoring of various natural disasters and is suitable for emergency monitoring and wide-area investigations of potential hazards involving geological disasters. [ABSTRACT FROM AUTHOR]

Although the atmospheric compensation models developed to date have been generally robust and effective for InSAR, how to choose the right atmospheric correction method for ground-based InSAR is worth studying. This paper uses different methods for atmospheric phase screen (APS) compensation based on studies of ground-based radar (GBR) to zero-baseline acquisitions over the Woda landslide in Sichuan, China. This landslide has a steep topography, thick fog, turbulent rivers and strong rains. Data were acquired at the Ku-band using a GAMMA Portable Radar Interferometer II (GPRI-II) in multiple campaigns (4 July 2019–13 July 2019). In 2019, the Miyun open-pit mine was also studied; the maximum deformation reached 4.03 mm/hour. The collected data were processed within one unit based on the small baseline set (SBAS) approach. The experimental results show the following (1) For long-distance monitoring with complex atmospheric disturbances, range- and/or height-dependent models fail. (2) The iterative decomposition (ITD) method can effectively address complex atmospheric disturbances. (3) If the threshold of wavelength is set to be large, the ITD method becomes a stratified model. [ABSTRACT FROM AUTHOR]

Detecting the slow motions of high and distant landslides in remote mountain areas has always been a problem. This paper takes the Woda landslide along the Jinsha River as an example to monitor landslide movement. Although some parts of the landslide body have been found to have moved in recent years, the timing and magnitude of motion have not been systematically monitored or interpreted. Here, we apply the SBAS time series strategy using 65-scene Sentinel-1A/B satellite InSAR images and study the spatial distribution and temporal behaviour of landslide movements between July 4, 2018, and August 29, 2020. Our research results show that the cumulative deformation on the left side of the landslide body with concentrated deformation was approximately 200 mm during the 2-year observation period. By calculating the relationship between the InSAR time series and the precipitation around the landslide, it is found that the landslide deformation is closely related to rainfall. GNSS technology is also deployed on the landslide mass and effectively complements InSAR technology. Simultaneously, based on the results of field surveys and hydrological data analysing the landslide's spatial deformation characteristics and deformation factors, the landslide deformation can also be inferred to be related to precipitation. The method used in this paper can be used for early recognition and early warning of high and remote landslides. [ABSTRACT FROM AUTHOR]

The Lenglongling Fault Zone (LLLFZ) is an important left‐lateral strike‐slip tectonic belt in the northeastern Tibetan Plateau (NETP), and the tectonic deformation and seismic activity of the LLLFZ reflect tectonic adjustments of the Qilian‐Haiyuan tectonic zone to the NETP. Although historical records of large earthquakes along the LLLFZ are not available, offset landforms reveal that large earthquakes have occurred. Therefore, offset landforms are used to study the seismic slip distribution to determine a fault slip model and earthquake recurrence behaviour based on an analysis of high‐resolution remote sensing images. Geomorphic markers associated with 316 systematically sinistrally deflected landforms were measured and analysed. The cumulative offset probability densities were analysed according to slip distributions measured along two segments of the fault. Offset density peaks in the eastern section of the fault decay exponentially with increasing offset size, suggesting that approximately seven palaeoearthquakes with an average slip of approximately 8 m occurred during the Holocene. The cumulative slips in the western segment increase gradually from west to east, with single‐event slips of approximately 2–3 m in the western part of the western segment and approximately 5–7 m in the eastern part. The seismic slip distributions of the LLLFZ indicate that the fault conforms to a quasi‐characteristic slip model. Both the eastern and western segments present typical left‐lateral strike‐slip movement. A magnitude of 8.0 was estimated for the LLLFZ palaeoearthquakes that occurred during the Holocene according to empirical relations. This study is helpful for understanding the tectonic deformation of the NETP. [ABSTRACT FROM AUTHOR]

For prediction of urban remote sensing surface temperature, cloud, cloud shadow and snow contamination lead to the failure of surface temperature inversion and vegetation‐related index calculation. A time series prediction framework of urban surface temperature under cloud interference is proposed in this paper. This is helpful to solve the problem of the impact of data loss on surface temperature prediction. Spatial and temporal variation trends of surface temperature and vegetation index are analyzed using Landsat 7/8 remote sensing data of 2010 to 2019 from Beijing. The geographically weighed regression (GWR) method is used to realize the simulation of surface temperature based on the current date. The deep learning prediction network based on convolution and long short‐term memory (LSTM) networks was constructed to predict the spatial distribution of surface temperature on the next observation date. The time series analysis shows that the NDBI is less than −0.2, which indicates that there may be cloud contamination. The land surface temperature (LST) modeling results show that the precision of estimation using GWR method on impervious surface and water bodies is superior compared to the vegetation area. For LST prediction using deep learning methods, the result of the prediction on surface temperature space distribution was relatively good. The purpose of this study is to make up for the missing data affected by cloud, snow, and other interference factors, and to be applied to the prediction of the spatial and temporal distributions of LST. This article is categorized under:Technologies > Machine Learning [ABSTRACT FROM AUTHOR]

In this study, multitemporal satellite images, unmanned aerial vehicle (UAV) photogrammetry and ground-based radar were utilized to investigate the formation mechanism and disaster features of different phases of the Xuyong landslide disaster that occurred in Sichuan Province on December 9, 2018. Field survey indicates that the estimated landslide volume is approximately 35000 m3. The landslide is a typical dualistic soil-rock structural landslide with bedding planes. The sliding surface is located in a thin layer of limestone which is characterized by the X-shaped conjugate joint planes. The steep slope has been cut and transformed by human disturbances, which have influenced the slope stability and the drainage of precipitation along the slope. Many factors, including the regional geological structure, stratum lithology, slope topography, landform morphology, and precipitation, have contributed to the Xuyong landslide during the pre-disaster phase. Post-disaster emergency observation revealed that subsequent deformation was located mainly along the back edge of the landslide, where the maximum surficial deformation reached only 18 mm/day over a small area, reflecting the low probability of a secondary landslide hazard. Our research provides significant guidelines for investigating potential landslide dangers in similar environments and for post-disaster emergency response using multiple remote sensing (RS) platforms. [ABSTRACT FROM AUTHOR]

The Tan-Lu fault zone (TLFZ) is one of the most important active faults in the eastern Chinese mainland, and the seismic activity of the Su-Lu segment is most prominent. The fault structures of the Su-Lu section are very complex and intersect with many other NW-striking and NE-striking fault zones, resulting in the extreme complexity of the crustal structure in this area. In this study, Bouguer gravity and aeromagnetic data are used to invert the crustal structures surrounding the Su-Lu segment and to construct a three-dimensional model. Our results indicate that the TLFZ presents obvious high anomalies in gravity and aeromagnetic fields, cuts through the Moho interface and acts as an upwelling passage for high-density materials from the uppermost mantle and asthenosphere. The gravity and aeromagnetic anomalies are greatly influenced by the crustal structures. Both the Moho and Curie interfaces are characterized by substantial undulations. The NW-striking and NE-striking faults intersect the TLFZ with different relations—for example, the Wuxi-Suqian fault and Cangshan-Nishan fault cut off the TLFZ with distinct gravity and aeromagnetic anomalies, and the Xintai-Mengyin fault and Mengshan piedmont fault cut off the western part of the TLFZ. In addition, most faults cut to the middle crust, and the lower crust is ductilely deformed because of magmatic underplating, reforming, remelting and thinning of the eastern North China block. Most earthquakes occur in the northern part of the Su-Lu segment, where magmatic activity is intense. [ABSTRACT FROM AUTHOR]

Areas with sharp spatial changes in crustal structure are usually considered prone to strong earthquakes, especially late Cenozoic structural zones. However, quantitative relationships have not been established between the occurrence of earthquakes and the extent to which the crustal structure changes. The crustal structure can be reflected by gravity anomalies. In this study, we investigate the crustal structure variation in the eastern Tibetan Plateau based on the gravity data acquired by the Gravity field and steady‐state Ocean Circulation Explorer satellite. The multiscales wavelet decomposition and power spectrum methods are used to analyze the spatial variation of crustal structure at different depths. Based on a fourth‐order wavelet map, four variable factors are constructed to represent the spatial variations of the crustal structure, and their statistical relationship with earthquakes is studied. The results show that the changing rate of the gravity anomalies is significantly positively correlated with the occurrence of earthquakes. Areas of high earthquake hazards are places where the gravity field changes dramatically, usually with a value of 11°–18° for the SLP (slope) index. The assessment efficiency of the SLP increases with the earthquake magnitude. According to the SLP index, several regions are assessed to have a high level of risk for strong earthquakes in the eastern Tibetan Plateau, including the Longmenshan Fault belt, where a Ms8.0 earthquake occurred in 2008, thus demonstrating the promising implications of our method in the earthquake susceptibility assessment. Plain Language Summary: The distribution of earthquake epicenters is uneven in space. At present, it is generally believed that locations with crustal material changes are prone to earthquakes. However, not all earthquakes are distributed in these locations. To answer the questions of how many earthquakes are distributed in these locations and whether these characteristics can be used to predict the locations of earthquakes, we construct some factors based on gravity data and active faults and conduct statistical analyses in this paper. The results show that the greater is the variation in the gravity field, the higher is the frequency of earthquakes. The assessment efficiency of these characteristics increases with the earthquake magnitude. Key Points: Based on the fourth‐order wavelet detail map of gravity, we constructed four quantitative indexes to express the spatial changes in the crustEarthquakes are concentrated in the high‐value region of the slope (SLP) factor, approximately 11°‐18°The earthquake risk assessment efficiency of the SLP increases with the earthquake magnitude [ABSTRACT FROM AUTHOR]

Estrogen receptors (ERs) are significant protein targets that can alter normal homeostatic transcription and signaling pathways. And the development of selective ER ligands is involved in the pharmacology of anticancer drugs, leading to the synthesis of numerous ER selective ligands. In the present work, three dimensional quantitative structure–activity relationship (3D-QSAR) models, including comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) in combination with molecular docking were performed on a series of ER ligands to investigate the potential relationship between the structural features of the compounds and its activity and selectivity. Good statistical significance was achieved for the CoMFA (ERα: R2cv = 0.676, R2pred = 0.631. ERβ: R2cv = 0.578, R2pred = 0.5341) and CoMISA (ERα: R2cv = 0.693, R2pred = 0.5758. ERβ: R2cv = 0.653, R2pred = 0.615) models. In addition, molecular docking results confirmed that the substituents at ring A, ring D and ring E were crucial for interacting with receptors ERα and ERβ, respectively, which were in agreement with the QSAR results. The substituents in ring A and ring F for ERα and residues Thr347/Ala302, Met388/Leu343, Leu391/Arg346, Met421/Ile376, Gly521/Leu476 for ERα and ERβ, respectively, contribute the most to the subtype selectivity. These results obtained from this work provide valuable information for the design of novel selective ER ligands with enhanced activity. [ABSTRACT FROM AUTHOR]

On March 20, 2019, a landslide (named Yagu landslide) occurred in eastern Tibetan Plateau. It produced a 10-m-high dam, resulting in a lake on the Songmai River, a tributary of the Jinsha River. This paper describes this slope failure and analyzes the process and cause of the landsliding based on the combination of Google Earth images, PlanetScope satellite optical images, field photography and geologic data. It is speculated that this event was likely induced by local human activity, such as quarrying rather than natural factors. This example raises a challenging issue whether the ongoing projects along the Jinsha River can induce landslides. In addition, the emergency responses of the government and the effort for risk removal of the dammed lake are presented. [ABSTRACT FROM AUTHOR]

This study investigates the 3 July 2015 (Mw=6.4) earthquake that affected Pishan County in Xinjiang, China. Using Synthetic Aperture Radar interferometry (InSAR), we mapped the near-field surface displacement of this event to better characterize the seismic source parameters. The inverted results suggest that a conjugate fault system could produce very similar deformation patterns as those observed in both ascending and descending InSAR observations, and the south-dipping fault is selected as the optimal fault responsible for the event. The selected fault was concentrated on a thrust fault with a strike of 112°, a dip of 25° and an average rake angle of 89°. The InSAR analysis reveals a fragmentation of the Western Kunlun north margin fault, and the overall deformation of the seismogenic fault is characterized by thrust motion, which is consistent with the transpressional tectonic characteristics of the major faults in this region. [ABSTRACT FROM AUTHOR]

The Yishu fault zone (YSFZ) is the most active fault in eastern China, and it is the location of an M 8.5 earthquake that occurred in 1668. However, topography and landforms in this area have been greatly altered by human activity during the previous three to four decades, which makes assessment of past earthquakes difficult. We therefore used a set of remote sensing images captured in the 1960s to evaluate the single-event and multievent cumulative offsets of streams along the fault. The local landforms have preserved the Holocene seismic offsets well despite the moderately humid climate in which the local landforms have evolved rapidly. Geomorphic markers associated with 401 systematically dextrally offset streams were analyzed and measured. These offset markers are considered to record seismic rupture processes. Cumulative offset probability densities were analyzed according to slip distributions along various subsections of the YSFZ. Four strong paleoearthquakes in addition to the 1668 earthquake were revealed by offset density peaks within the YSFZ, a finding that differs from those of previous studies. The average offset of the 1668 event is approximately 9 m. The cumulative offsets of the other four paleoseismic events are essentially multiples of the latest event. A single event ruptured more than 200 km of discontinuous fault traces. The similarity of the previous five earthquakes implies that rupturing of the YSFZ has followed a characteristic slip model during the Holocene, with a right-lateral slip rate of 2.2-2.6 mm/yr. We expect that the YSFZ is not due for another large earthquake for several thousand years. [ABSTRACT FROM AUTHOR]

The M 6.4 Menyuan earthquake occurred on the northern side of the Lenglongling fault (LLLF) in the mid-western of the Qilian-Haiyuan fault zone on January 21, 2016. The earthquake epicenter was distant from the Minle-Damaying and Huangcheng-Shuangta faults, eastern of the Northern Qilian Shan fault zone. A near northwest-striking rupture plane intersects the two faults at a certain angle. The focal mechanism solution shows that this was a thrust-type earthquake, slightly different from the strike-slip movement with a thrust component of the LLLF. Field geological mapping, tectonic geomorphology analysis, trench excavation and C dating reveal that (1) the LLLF has been obviously active since the Holocene, and may behave with characteristic slip behavior and produce M 7.3-7.5 earthquakes; (2) the LLLF appears as a flower structure in terms of structure style, and dips NNE at a steep angle; and (3) the most recent earthquake event occurred after 1815-1065 a BP. An associated fault, the Northern Lenglongling fault (NLLLF), is located at the northwestern end of the LLLF. Consequently, the NLLLF was continually subject to tectonic pushing effects from the left-lateral shear at the end of the LLLF, and, accordingly, it bent and rotated outward tectonically. Subsequently, the fault deviated from the dominant rupture azimuth and activity weakened. In the late Quaternary, it behaved as a thrust fault with no obvious deformation at the surface. This is indicated by the arc shape, with a micro-protrusion northeastward, and no geologic or geomorphic signs of surface rupturing since the late Quaternary. However, such faults could still rupture at depth, producing moderate-strong earthquakes. The geometric and kinematic properties of the NLLLF are in good agreement with the occurrence and kinematic properties of nodal plane 2, and with the distribution characteristics of the aftershocks and seismic intensity. Therefore, the NLLLF is a more suitable seismogenic structure for the M 6.4 Menyuan earthquake. In addition, the thrust movement of the NLLLF accommodates subsequent movement of the LLLF. During the historical evolution of the NLLLF, the LLLF and the NLLLF have affected the local topography through tectonic uplift. [ABSTRACT FROM AUTHOR]

The Damxung-Yangbajain rift is one of the most active north-south trending rifts in the south Tibetan Plateau, and it has been playing an important role in accommodating the east-west extension of the Tibetan Plateau. Both stream profiles on the Nyainqentanglha Range adjacent to the northwest part of the Damxung-Yangbajain rift and tectonic geomorphology in the north of the rift are analyzed to assess the spatial pattern and intensity of rock uplift which is related to neotectonic activity. A total of 85 stream profiles across the Nyainqentanglha Range are analyzed, and 111 knickpoints are interpreted. Most of these stream profiles are characterized by prominent convexities with two or more knickpoints, many of which are formed due to the strong rock uplift evidenced by abnormal concavity and extremely high steepness indices during the Quaternary. Neotectonic activity in this region is well replicated in the stream profile indices and offset landforms. Tectono-geomorphic analysis shows that the concavity and steepness indices correlate with the fault movements at many places. The Damxung-Yangbajain rift is characterized by left-lateral strike-slip in the north of Damxung and by normal movement in middle and southern parts. The middle and southern parts have been undergoing higher uplift than has the northern area. It is most likely that the strong uplift is related to the heat flow under the crust. Earthquakes occurring in the Damxung-Yangbajain rift, including a M8 in 1411 and M6.6 in 2008, are thought to be related to heat flow activity. All of the stream profile indices and tectonic geomorphology show that the Damxung-Yangbajain rift is not in a stable state. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Yangbajain contains the largest geothermal energy power station in China. Geothermal explorations in Yangbajain first started in 1976, and two plants were subsequently built in 1981 and 1986. A large amount of geothermal fluids have been extracted since then, leading to considerable surface subsidence around the geothermal fields. In this paper, InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR images. In the case of the TerraSAR-X data, most orbital fringes were removed using precise orbits during the interferometric processing. However, residual orbital ramps remain in some interferograms due to the uncertainties in the TerraSAR-X orbits. To remove the residual orbital ramps, we estimated a best-fit ‘twisted plane’ for each epoch interferogram using quadratic polynomial models based on a network approach. This method removes most of the long-wavelength signals, including orbit ramps and atmospheric effects. The vertically stratified component (Topography Correlated Atmospheric Delay, TCAD) was also removed using a network approach. If the influence of seasonal frozen ground (SFG) is not taken into consideration, our results show that the subsidence rate around power plant I (the south plant) is approximately 20 mm/yr with a peak of 30 mm/yr. The subsidence rate around power plant II (the north plant) is approximately 10 mm/yr, when accounting for the influence of SFG on the power plant and its surrounding ground surface. Our results show that ground motion is caused by seasonal frozen ground and is strongly related to the temperature change. [ABSTRACT FROM PUBLISHER]

Using the Bam earthquake as an example, we apply the multiple-aperture interferometry (MAI) algorithm to measure the azimuth (AZI) displacement with multiple mode synthetic aperture radar (SAR) images (ScanSAR and image modes) and further on produce the 3-D coseismic displacement maps using well-known models: multiple independent interferometric SAR (InSAR) with different viewing angles and combining MAI with conventional InSAR. The 3-D displacement maps show that, besides accuracy of SAR observation, inversion model is another major perturbing factor limiting the accuracy of 3-D component reconstruction. That is, in the former model, the smaller the difference of incidence angles is, the more easily influenced by ill-conditioned systems the estimated parameters are. Based on characteristics of error sources of SAR observations, we classify observation errors into random error, systematic error, and gross error. Moreover, their characteristics of error propagation are analyzed in the two models, respectively. Error propagation analysis indicates that random errors only affect variability of inversion result, while systematic error and gross error cause not only variability but also bias or uncertainty in estimated parameters. The presented error analysis method provides a more comprehensive understanding of bias or uncertainty of 3-D estimated components, which will be a useful tool for evaluating errors in displacement fields obtained from SAR observations. In this letter, we also group multiple InSAR and MAI observations to estimate 3-D components using weighted least squares whose weights are given by the Förstner posterior variance estimation, which may avoid an ill-conditioned system, reducing line-of-sight and AZI random noises and improving accuracies of estimated 3-D components. [ABSTRACT FROM PUBLISHER]

Due to temporal and spatial decorrelation and other noise, the integer-cycle jumps always appear in the unwrapped phase. It is well known that phase unwrapping errors represent one of the major limitations of Interferometric SAR (InSAR). A phase closure method is presented to detect and correct phase unwrapping errors for discrete coherent points in InSAR time series analysis. Its application to ENVISAT Advanced Synthetic Aperture Radar (ASAR) data over the coastal zone of Cang-zhou, Hebei Province showed a significant improvement in the InSAR time series results, with the number of valid coherent pixels increasing from 68 000 to 186 400 and the root mean square (RMS) decreasing from 13. 1 mm to 5. 3 mm and 17. 5 mm to 4. 3 mm for two deforming areas respectively. [ABSTRACT FROM AUTHOR]