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Characterizing the coseismic slip behaviors of earthquakes could offer a better understanding of regional crustal deformation and future seismic potential assessments. On 18 December 2023, an Mw 6.0 earthquake occurred on the Lajishan–Jishishan fault system (LJFS) in the northeastern Tibetan Plateau, causing serious damage and casualties. The seismogenic fault hosting this earthquake is not well constrained, as no surface rupture was identified in the field. To address this issue, in this study, we use Interferometric Synthetic Aperture Radar (InSAR) data to investigate the coseismic surface deformation of this earthquake and invert both ascending and descending line-of-sight observations to probe the seismogenic fault and its slip characteristics. The InSAR observations show up to ~6 cm surface uplift caused by the Jishishan earthquake, which is consistent with the thrust-dominated focal mechanism. A Bayesian-based dislocation modeling indicates that two fault models, with eastern and western dip orientations, could reasonably fit the InSAR observations. By calculating the coseismic Coulomb failure stress changes (∆CFS) induced by both fault models, we find that the east-dipping fault scenario could reasonably explain the aftershock distributions under the framework of stress triggering, while the west-dipping fault scenario produced a negative ∆CFS in the region of dense aftershocks. Integrating regional geological structures, we suggest that the seismogenic fault of the Jishishan earthquake, which strikes NNE with a dip of 56° to the east, may be either the Jishishan western margin fault or a secondary buried branch. The optimal finite-fault slip modeling shows that the coseismic slip was dominated by reverse slip and confined to a depth range between ~5 and 15 km. The released seismic moment is 1.61 × 1018 N·m, which is equivalent to an Mw 6.07 earthquake. While the Jishishan earthquake ruptured a fault segment of approximately 20 km, it only released a small part of the seismic moment that was accumulated along the 220 km long Lajishan–Jishishan fault system. The remaining segments of the Lajishan–Jishishan fault system still have the capability to generate moderate-to-large earthquakes in the future. [ABSTRACT FROM AUTHOR]

Three cases of microphysical characteristics and kinematic structures in the negative temperature region of summer mesoscale cloud systems over the eastern Tibetan Plateau (TP) were investigated using X-band dual-polarization radar. The time-height series of radar physical variables and mesoscale horizontal divergence δ ¯ derived by quasi-vertical profiles (QVPs) indicated that the dendritic growth layer (DGL, −20°C to −10°C) was ubiquitous, with large-value zones of KDP (specific differential phase), ZDR (differential reflectivity), or both, and corresponded to various dynamic fields (ascent or descent). Ascents in the DGL of cloud systems with vigorous vertical development were coincident with large-value zones of ZDR, signifying ice crystals with a large axis ratio, but with no obvious large values of KDP, which differs from previous findings. It is speculated that ascent in the DGL promoted ice crystals to undergo further growth before sinking. If there was descent in the DGL, a high echo top corresponded to large values of KDP, denoting a large number concentration of ice crystals; but with the echo top descending, small values of KDP formed. This is similar to previous results and reveals that a high echo top is conducive to the generation of ice crystals. When ice particles fall to low levels (−10°C to 0°C), they grow through riming, aggregation, or deposition, and may not be related to the kinematic structure. It is important to note that this study was only based on a limited number of cases and that further research is therefore needed. [ABSTRACT FROM AUTHOR]

Located on the southeastern periphery of the Tibetan Plateau, the Xianshuihe fault (XSHF) is an active left-lateral strike-slip fault renowned for its frequent and intensive seismic activities. This highlights the necessity of employing advanced geodetic methodologies to precisely evaluate the fault kinematics and seismic hazard potential along this fault. Among these techniques, interferometric synthetic aperture radar (InSAR) stands out for its high spatial resolution and regular revisit intervals, enabling accurate mapping of interseismic deformation associated with fault motion. However, the precision of InSAR in measuring deformation encounters several challenges, particularly artifacts stemming from phase unwrapping errors and atmospheric phase delays. In this study, we utilize ascending and descending Sentinel-1 InSAR images spanning from January 2017 to January 2023 to drive the line-of-sight (LOS) mean crustal velocities associated with the XSHF with emphasis on phase unwrapping errors and atmospheric delay corrections. Then, the reliability of the derived LOS velocities is assessed using independent observations from the Global Navigation Satellite System (GNSS). The inferred fault slip rate along the XSHF shows significant along-strike variations, gradually decreasing from ~11.1 mm/yr at the Luhuo section to ~6.6 mm/yr at the Kangding section and then sharply increasing to ~13.0 mm/yr towards its eastern terminus at the Moxi section. The fault locking depth shows similar along-strike variations, decreasing from ~19.5 km in the northwestern part to ~4.8 km at the Kangding section, before increasing to 19.6 km at the Moxi segment. Notably, apparent surface fault creeping, characterized by a slip rate of ~2.7 mm/yr, is observed at the Kangding segment, likely resulting from postseismic slip following the 2014 Mw 6.3 Kangding earthquake. [ABSTRACT FROM AUTHOR]

The 2021 MW 7.4 Maduo event occurred within the Bayan Har block in eastern Tibet, which provides an opportunity to investigate the stress conditions and rheology of faults within the block. Here, we perform dynamic rupture simulations based on the finite element method to explore the physical conditions underlying this earthquake and the factors that controlled the rupture process. We construct the model with a nonplanar fault inferred from the Interferometric Synthetic Aperture Radar (InSAR) data and aftershocks sequence relocation. Our dynamic model is controlled by slip‐weakening friction law with initial stress on fault resolved from a uniform regional stress field. The preferred model produces an average slip of ∼2.2 m with a maximum slip of ∼4.0 m. There are three asperities distributed along the strike, which have captured the main features of the Maduo event. The simulation results are consistent with the static GPS coseismic surface displacements, InSAR data, and displacement waveforms recorded by high‐rate GNSS stations. By comparing the results with the planar fault model and rotated stress fields, we find that the fault geometry and regional stress field are the primary factors that control the rupture process of the event. Moreover, we infer that the unfavorable orientation and fault bend lead to minor slips on the branch fault. Furthermore, we investigate the potential mechanisms of supershear rupture on the eastern fault segment. Plain Language Summary: The 2021 Maduo event ruptured on an intra‐block fault of the Bayan Har block in the Tibetan Plateau, which has aroused widespread interest among the scientific community. In this study, we perform physics‐based numerical simulations based on a nonplanar fault to reproduce the source process of the event. The surface displacements obtained from our dynamic model are in good agreement with the observations. As the other parameters are relatively simple in our model, the source process of the event is mainly controlled by the geometric fault complexities. Our results also help to constrain the orientation of the regional stress field. We find that the branch fault of the earthquake is unfavorably oriented in the regional stress field as well as the fault bend also impedes the rupture to propagate on it, which leads to a minor slip on the branch fault. Furthermore, we infer that the supershear rupture may be induced by the free surface in the earthquake. Key Points: Our dynamic model reproduced the first‐order rupture characteristics of the Maduo earthquakeThe main factor that controls the multipeak slip pattern of the Maduo event is fault geometryThe orientation of the regional stress field was determined through numerical experiments [ABSTRACT FROM AUTHOR]

Mêdog is located at the entrance of the water vapor channel of the Yarlung Tsangpo Great Canyon on the southeastern Tibetan Plateau (TP). In this study, the seasonal variation in the microphysical vertical structure of stratiform precipitation at the Mêdog site in 2022 was investigated using micro rain radar (MRR) observations, as there is a lack of similar studies in this region. The average melting layer height is the lowest in February, after which it gradually increases, reaches its peak in August, and then gradually decreases. For lower rain categories, the vertical distribution of small drops remains uniform in winter below the melting layer. The medium-sized drops show slight increases, leading to negative gradients in the microphysical profiles. Slight or evident decreases in concentrations of small drops are observed with decreasing height in the premonsoon, monsoon, and postmonsoon seasons, likely due to significant evaporation. The radar reflectivity, rain rate, and liquid water content profiles decrease with decreasing height according to the decrease in concentrations of small drops. With increasing rain rate, the drop size distribution (DSD) displays significant variations in winter, and the fall velocity decreases rapidly with decreasing height. In the premonsoon, monsoon, and postmonsoon seasons, the concentrations of large drops significantly decrease below the melting layer because of the breakup mechanism, leading to the decreases in the fall velocity profiles with decreasing height during these seasons. Raindrops with sizes ranging from 0.3–0.5 mm are predominant in terms of the total drop number concentration in all seasons. Precipitation in winter and postmonsoon seasons is mainly characterized by small raindrops, while that in premonsoon and monsoon seasons mainly comprises medium-sized raindrops. Understanding the seasonal variation in the vertical structure of precipitation in Mêdog will improve the radar quantitative estimation and the use of microphysical parameterization schemes in numerical weather forecast models over the TP. [ABSTRACT FROM AUTHOR]

The distribution and magnitude of forces driving lithospheric deformation in the India‐Eurasia collision zone have been debated over many decades. Here we test a two‐dimensional (2‐D) Thin Viscous Shell approach that has been adapted to explicitly account for displacement on major faults and investigate the impact of lateral variations in depth‐averaged lithospheric strength. We present a suite of dynamic models to explain the key features from new high‐resolution Sentinel‐1 Interferometric Synthetic Aperture Radar as well as Global Navigation Satellite System velocities. Comparisons between calculated and geodetically observed velocity and strain rate fields indicate: (a) internal buoyancy forces from Gravitational Potential Energy acting on a relatively weak region of highest topography (>2,000 m) contribute to dilatation of the high plateau and contraction on the margins; (b) a weak central Tibetan Plateau (∼1021 Pa s compared to far‐field depth‐averaged effective viscosity of at least 1022–1023 Pa s) is required to explain the observed long‐wavelength eastward velocity variation; (c) localized displacement on fault systems enables strain concentration and clockwise rotation around the Eastern Himalayan Syntaxis. We discuss the tectonic implications for rheology of the lithosphere, distribution of geodetic strain, and partitioning of active faulting and seismicity. Plain Language Summary: The collision of the Indian Plate with Eurasia has created the Tibetan Plateau, one of the largest deforming regions in the continents. The mode of deformation has been a focus for heated debate and has inspired two contrasting tectonic models: (a) The deformation is localized on major faults separating "blocks" or (b) the strain is distributed throughout a "continuum." We approximate the India‐Eurasia collision by treating the continent as a thin viscous shell with regional variations in strength, explicitly accounting for displacements on selected major faults. We present a suite of models to explain the key features of new geodetic measurements from satellites. The best‐fit model involves a weak Tibetan Plateau, a particularly weaker central plateau, and four strong regions outside the plateau, and allows displacements on major faults. This represents the deformation field of the India‐Eurasia collision zone as a combination of continuous distributed deformation and focused strain on major faults. Key Points: A suite of faulted viscous shell models testing key parameters explain new observations from geodesy for the India‐Asia collisionThe India‐Asia collision is explained by the balance between buoyancy and boundary forces, slip on faults, and internal strength variationsCentral Tibetan Plateau has a vertically‐averaged effective viscosity of ∼1021 Pa s, 1–2 orders lower than the surrounding area [ABSTRACT FROM AUTHOR]

The Haiyuan fault system plays a crucial role in accommodating the eastward expansion of the Tibetan Plateau (TP) and is currently slipping at a rate of several centimeters per year. However, limited seismic activities have been observed using geodetic techniques in this area, impeding the comprehensive investigation into regional tectonics. In this study, the geometric structure and source models of the 2022 Mw 6.7 and the 2016 Mw 5.9 Menyuan earthquakes were investigated using Sentinel-1A SAR images. By implementing an atmospheric error correction method, the signal-to-noise ratio of the 2016 interferometric synthetic aperture radar (InSAR) coseismic deformation field was significantly improved, enabling InSAR observations with higher accuracy. The results showed that the reliability of the source models for those events was improved following the reduction in observation errors. The Coulomb stress resulting from the 2016 event may have promoted the strike-slip movement of the western segment of the Lenglongling fault zone, potentially expediting the occurrence of the 2022 earthquake. The coseismic slip distribution and the spatial distribution of aftershocks of the 2022 event suggested that the seismogenic fault may connect the western segment of the Lenglongling fault (LLLF) and the eastern segment of the Tuolaishan fault (TLSF). Additionally, the western segment of the surface rupture zone of the northern branch may terminate in the secondary branch close to the Sunan-Qilian fault (SN-QL) strike direction, and the earthquake may have triggered deep aftershocks and accelerated stress release within the deep seismogenic fault. [ABSTRACT FROM AUTHOR]

In recent decades, glaciers in the southeastern Tibetan Plateau (SETP) have been rapidly melting and showing a large scale of glacier mass loss. Due to the lack of large-scale, high-resolution, and high-precision observations, knowledge on the spatial distribution of the glacier mass balance and the response to climate change is limited in this region. We propose a TanDEM-X bi-static InSAR (Interferometric Synthetic Aperture Radar) algorithm with a non-local mean filter method and difference strategy, to improve the precision of glacier surface elevation change detection. Moreover, we improved the glacier mass balance estimation algorithm with a correction method for multi-source system errors and an uncertainty evaluation method based on error propagation theory to reduce the uncertainty of estimations. We used 13 pairs of TanDEM-X bi-static InSAR images to obtain the glacier mass balance data for the entire SETP. The total area of glaciers monitored was 5821 km2 and the total number of glaciers monitored was 2321; the glacier surface elevation change rate was −0.505 ± 0.005 m/yr, and the glacier mass balance estimation was −454.5 ± 13.1 mm w.eq. during 2000–2014. Additionally, we analyzed the spatial distribution of the glacier mass balance within the SETP using the sub-watershed analysis method. The results showed that the mass loss rate had a decreasing trend from the southeast to the northwest. Furthermore, the temperature change and the glacier mass loss rate showed a positive correlation from the southeast to the northwest in this region. This study greatly advances our understanding of the regularities of glacier dynamics in this region, and can provide scientific support for major national goals such as the rational utilization of surrounding water resources and construction of important transportation projects. [ABSTRACT FROM AUTHOR]

The upstream Jinsha River, located in the eastern Tibetan Plateau, has been experiencing intense geological hazards characterized by a high density of ancient landslides, significant deformation and reactivation challenges. In this study, remote sensing interpretation, field investigations, and Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technologies have been employed. Along a 17 km stretch of the Jinsha River, specifically in the Xiongba-Sela segment, 16 large-scale ancient landslides were identified, 9 of which are currently undergoing creeping deformation. Notably, the Sela and Xiongba ancient landslides exhibit significant deformation, with a maximum deformation rate of −192 mm/yr, indicating a high level of sliding activity. The volume of the Sela ancient landslide is estimated to be 1.8 × 108 to 4.5 × 108 m3, and characterized by extensive fissures and long-term creeping deformation. The SBAS-InSAR results revealed significant spatial variations in the deformation of the Sela ancient landslide, generally displaying two secondary zones of intense deformation, and landslide deformation exhibits nonlinear behavior with time. Between January 2016 and February 2022, Zone III1 on the southwest side of the Sela ancient landslide, experienced a maximum cumulative deformation of −857 mm, with a maximum deformation rate of −108 mm/yr. Zone III2, on the northeast side of the Sela ancient landslide, the maximum cumulative deformation was −456 mm, with a maximum deformation rate of −74 mm/yr; among these, the H2 and H4 secondary bodies on the south side of III1 are in the accelerative deformation stage and at the Warn warning level. We propose that the large-scale flood and debris flow disasters triggered by the Baige landslide-dammed lake-dam broken disaster chain in Tibetan Plateau during October and November 2018 caused severe erosion at the foot of downstream slopes. This far-field triggering effect accelerated the creep of the downstream ancient landslides. Consequently, the deformation rate of Zone III2 of the Sela ancient landslide increased by 6 to 8 times, exhibiting traction-type style reactivation. This heightened activity raises concerns about the potential for large-scale or overall reactivation of the landslide, posing a risk of damming the Jinsha River and initiating a dam-break disaster chain. Our research on the reactivation characteristics and mechanisms of large ancient landslides in high deep-cut valleys provides valuable guidance for geological hazard investigation and risk prevention. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau vortex (TPV), as an α-scale mesoscale weather system, often brings severe weather conditions like torrential rain and severe convective storms. Based on the detections from the Global Precipitation Measurement (GPM) Core Observatory's Dual-frequency Precipitation Radar (DPR) and the FY-4A satellite's Advanced Geostationary Radiation Imager (AGRI), combined with ERA5 reanalysis data, the precipitation characteristics of a TPV moving eastward during 8–13 July 2021 at different developmental stages are explored in this study. It was clear that the near-surface precipitation rate of the TPV during the initial stage at the eastern Tibetan Plateau (TP) was below 1 mm·h−1, implying overall weak precipitation dominated by stratiform clouds. After moving out of the TP, the radar reflectivity factor (Ze), precipitation rate, and normalized intercept parameter (dBNw) significantly increased, while the proportion of convective clouds gradually rose. Following the TPV movement, the distribution range and vertical thickness of Ze, mass-weighted mean diameter (Dm), and dBNw tended to increase. The high-frequency region of Ze appeared at 15–20 dBZ, while Dm and dBNw occurred at around 1 mm and 33 mm−1·m−3, respectively. Near the melting layer, Ze was characterized by a significant increase due to the aggregation and melting of ice crystals. The precipitation rate of convective clouds was generally greater than that of stratiform clouds, whilst both of them increased during the movement of the TPV. Particularly, at 01:00 on 12 July, there was a significant increase in the precipitation rate and Dm of convective clouds, while dBNw noticeably decreased. These findings could provide valuable insights into the three-dimensional structure and microphysical characteristics of the precipitation during the movement of the TPV, contributing to a better understanding of cloud precipitation mechanisms. [ABSTRACT FROM AUTHOR]

• Ice penetration impact on CryoSat-2 altimetry is examined in 257 lakes in cold area. • The average of maximum underestimation on lake levels by CryoSat-2 is ∼0.90 m. • The underestimation of lake level in Eurasia is smaller than that for North America. • The highest number of lakes with maximum level underestimation occurs in March. The CryoSat-2 satellite provides high-precision and long-term monitoring of global lake levels, offering advantages for water resource management, ecological protection, and disaster warning. However, the lake ice penetration by radar electromagnetic waves of CryoSat-2 altimetry tends to result in underestimation of water levels for lakes in high latitudes and altitudes. By contrast, the laser altimetry of ICESat-2 enables us to obtain the height measurements from lake ice surface and the ice penetration impacts on lake levels can be nearly ignored in the ICESat-2 elevation product. After converting the CryoSat-2 and ICESat-2 altimetry data to the same datum and height reference system, the water level difference of (near-) synchronous observations between the two satellites could be mainly attributed to the influences by the lake ice penetration from CryoSat-2 data. In this study, totally 257 lakes in high-latitude (north of 50°N) and high-altitude (the Tibetan Plateau, TP) regions that are covered by both CryoSat-2 and ICESat-2 satellite tracks are examined to explore the characteristics of ice penetration impacts on water level measurements. The altimetry data during unfreezing seasons (June to October) are used to correct the systematic height biases of these two satellite measurements, thus their water level differences during freezing seasons (November to May of the following year) are deemed as the influences of ice penetration on lake level measurements by CryoSat-2 radar altimetry. The results show that the maximum underestimation depth of water level for each lake varies within the range of 0.01–3.47 m, with an average of 0.90 m. Particularly in North America with a dense distribution of lakes, the underestimation of lake levels by CryoSat-2 gradually ascends with increasing latitude. CryoSat-2 underestimates lake levels in Europe and the TP less than in North America. Among different months, the lake ice leads to the maximum underestimation on the water level by CryoSat-2 altimetry in March. The spatial and temporal characteristics of lake ice impacts on the water level measurements by CryoSat-2 altimetry would be an essential reference for quantifying and reducing the uncertainties of satellite radar altimetry for monitoring inland water dynamics. [ABSTRACT FROM AUTHOR]

• The water released from ground ice melting is quantified from surface deformation. • Ground ice melting released water accounts for 19.3% of the lake volume increase. • The loss of cryospheric storage has largely (80%) offset the water gain in the lake. The Dogai Coring Lake on the Tibetan Plateau, with widespread permafrost and glaciers in the watershed, has expanded rapidly between 2014 and 2020. However, it remains unclear how much melting water from permafrost and glaciers contributes to the increase in lake volume. This study quantifies the potential amount of water released by the melt of permafrost and glaciers, and assesses the fraction of water storage gains in the lake offset by the loss from the cryosphere (i.e., ground ice and glaciers). The small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) method was used to derive the spatiotemporal changes in surface deformation, which then assisted the estimation of the potential water release from ground ice melting. The glacier mass balance was estimated using a geodetic method with ASTER DEMs. Results show that 51.3 % of the region experienced subsidence with rates in the range of 5–20 mm∙a−1 during 2014–2020. Ground ice melting released water at a rate of 35.1 × 106 m3∙a−1, accounting for ∼19.3 % of the increase in lake volume. The glacier mass loss rate was estimated to be − 0.69 ± 0.04 m w.e. yr−1 (113.6 ± 7.3 × 106 m3∙a−1), contributing ∼62.5 % to the lake volume increase. Our results show that the water storage loss in the cryosphere has largely (∼80 %) offset the water storage gain in the lake, suggesting that cryospheric meltwater is an important factor regulating water budget change of the lake watershed. [ABSTRACT FROM AUTHOR]

High‐resolution present‐day earth surface deformation maps from satellites provide important data constraints, which help us better understand tectonic processes and analyze seismic hazards. Here, we use Sentinel‐1 Radar images (2014–2020) and accurate positioning measurements (2009–2019) to get a high‐resolution three‐dimensional earth surface velocity map for the northeastern Tibetan Plateau, and we invert the slip rate and coupling ratio of major regional faults. We find ∼4 mm/yr uplift along an arc from the Qilianshan to Lajishan, relative to the neighboring low‐elevation area to the east, which indicates ongoing rapid orogeny. We find transient deformation along the Laohushan and 1920 M8.5 Haiyuan rupture segments of the Haiyuan fault, whereas the western Haiyuan, southern Liupanshan, central Lajishan and central‐western West Qinling faults are essentially locked above 15–20 km, suggesting a potentially high seismic hazard. Plain Language Summary: The northeast Tibetan Plateau, which is impeded by the tectonically stable Ordos block, continues to grow in response to the far‐field India‐Eurasia collision. This region has several large‐scale active faults that hosted some destructive earthquakes in the last 100 years. Although intensively studied, the fault kinematics of those seismogenic faults are still not clear, mainly because of poor observational constraints. Hence, high‐resolution present‐day deformation maps are essential to answering this question, either of scientific or societal concern. We provide satellite‐based ground deformation rate maps with mm‐accuracy for this region. They show shallow fault creep along some segments of the Haiyuan fault which is better constrained than previous results, active tectonic uplift in the Lajishan. Our work gives new constraints for the seismic hazard for the Northeastern Tibetan Plateau case. Key Points: We derive a new high‐resolution three‐dimensional present‐day deformation map for the Northeastern Tibetan PlateauGeodetic data reveals ongoing rapid uplift along an accurate orogenic belt from the eastern Qilianshan and LajishanNew constraints for the seismic hazard analysis for the Northeastern Tibetan Plateau [ABSTRACT FROM AUTHOR]