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The geographical location of Yunnan province is at the upstream area of water vapor transportation from the Bay of Bengal and the South China Sea to inland China. Understanding the spatiotemporal variations of water vapor over this region holds significant importance. We utilized the Global Navigation Satellite System (GNSS) data collected from 12 stations situated in Yunnan, which are part of the Crustal Movement Observation Network of China, to retrieve hourly precipitable water vapor (PWV) data from 2011 to 2022. The retrieved PWV data at Station KMIN were evaluated by the nearby radiosonde data, and the results show that the mean bias and RMS of the differences between the two datasets are 0.08 and 1.78 mm, respectively. Average PWV values at these stations are in the range of 11.77 to 33.53 mm, which decrease from the southwest to the north of Yunnan and are negatively correlated with the stations' heights and latitudes. Differences between average PWV in the wet season and dry season range from 12 to 27 mm. These differences tend to increase as the average PWV increases. The yearly rates of PWV variations, averaging 0.18 mm/year, are all positive for the stations, indicating a year-by-year increase in water vapor. The amplitudes of the PWV annual cycles are 9.75–20.94 mm. The spatial variation of these amplitudes is similar to that of the average PWV over the region. Generally, monthly average PWV values increase from January to July and decrease from July to December, and the growth rate is less than the decline rate. Average diurnal PWV variations show unimodal PWV distributions over the course of the day at the stations except Station YNRL, where bimodal PWV distribution was observed. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine co- and post-seismic deformation following the 2011 M w9.0 Tohoku–Oki earthquake and its impact on Northeast Asia. Large-scale, long-term post-seismic deformation caused by the earthquake was extracted according to the continuous Global Navigation Satellite Systems (GNSS) observation data for Japan, South Korea, Northeast China and the Far East Russia. The present research adopted a 2-D viscoelastic model to simulate the observed large-scale seismic deformation, considering the subducting slab in the western Pacific. The duration of the after-slip in the northwest of the main rupture area was found to be greater than that in the south of the main rupture area (approximately 6 yr). The steady-state viscosity coefficient of the continental mantle was found to be 8 × 1018 Pa·s. Post-seismic deformation in Northeast Asia was primarily caused by viscoelastic relaxation of the mantle, and observations on the west side of the Tan-Lu fault were smaller than simulation, revealing the heterogeneity in viscosity structures in NE China. [ABSTRACT FROM AUTHOR]

The southeastern margin of the Tibetan Plateau is one of the most significant deforming regions in China, and even the world, leading to an urgent need to assess the potential earthquake hazard along its complex geological structures. The moment deficit estimate is a well-established way of assessing earthquake hazards in seismic zones. In this study, we derive an improved crustal deformation field for the southeastern margin of the Tibetan Plateau by using a new Global Positioning System (GPS) dataset that includes both the published and latest observations from the Crustal Movement Observation Network of China from 1998 to 2020. We employ the new GPS velocities to estimate two-dimensional strain rates in the southeastern Tibetan Plateau, including the derivatives of maximum shear strain rates. The geodetic strain rates are used to calculate the geodetic moment accumulation rates, which are then compared with the seismic moment release derived from historical earthquakes over the past hundreds of years at 14 seismic zones. Our results reveal that the crustal strain accumulation is substantially released by earthquakes occurring in the Xianshuihe, Xiaojiang, and Chuxiong–Jianshui zones. For the remaining seismogenic zones, the geodetic moment rates are found to be remarkably higher than the seismic rates, with ratios of around 2.1–7.8. In the Litang–Muli, Ganzi–Yushu, Songpan–Longmenshan, western Yunnan, and Anninghe zones, the seismic moment rate deficits are estimated to be 3.6 × 1017 Nm/year, 15.5 × 1017 Nm/year, 20.2 × 1017 Nm/year, 11.0 × 1017 Nm/year, and 21.8 × 1017 Nm/year, respectively, indicating a possible high level of seismic hazard in the future. However, aseismic processes such as creep and ductile deformation might modulate a large proportion of the total strain accumulation in the northwestern Yunnan zone, possibly accounting for the discrepancies between the estimated geodetic and seismic moments and thus making the assessment of earthquake potential quite vague. This study demonstrates that insightful comparison of geodetic and seismic moments could be beneficial for assessing earthquake hazards on the southeastern margin of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The Mw 7.8 Kaikōura, North Canterbury, New Zealand earthquake, which occurred on 14 November 2016 (local time), was one of the most complex continental earthquakes ever documented and among the largest instrumentally recorded events in New Zealand history. The epicenter was located at the southern termination of the Hikurangi margin, where the subducting Pacific Plate transfers into the dextral Alpine transform fault. In this work, we precisely estimate three-dimensional coseismic and postseismic displacements caused by this event from continuous global navigation satellite systems (GNSS) stations in New Zealand. The Kaikōura earthquake activated significant and diverse coseismic and postseismic deformation on a large spatial scale, located mainly in the southern part of the North Island and the northern part of the South Island. Station CMBL had the largest coseismic offsets and the most remarkable postseismic displacements. The accumulated postseismic displacements at this station reached 13, 7 and 29% of the coseismic values on the east, north and vertical components, respectively, in the first 1.5 years after the mainshock. Integrating our estimated coseismic displacements with previously published coseismic displacements, we inverted for the spatial distribution of coseismic slip and spatiotemporal evolution of postseismic slip. Our optimal coseismic model suggests that rupture occurred both on shallow crustal faults, and to some extent at the southern Hikurangi subduction interface. The GPS-inverted coseismic moment release is equivalent to an Mw 7.9 event. The postseismic slip was not only significantly extended at the subduction interface, but also appeared on the Needles fault. The cumulative moment magnitude is Mw 7.35 in the first 1.5 years after the event, and Mw 7.35, Mw 6.95 and Mw 6.80 during the periods 0.0–0.5, 0.5–1.0 and 1.0–1.5 years, respectively, indicating rapid decay of the postseismic deformation. Comparing the spatial distribution of the postseismic to the coseismic slip, although their direction is similar, the discrepancy between their location is significant: the slip located along the shallow crustal faults activated the coseismic deformation, while the slip located on the deep subduction interface controlled the postseismic deformation. [ABSTRACT FROM AUTHOR]

We re-estimated the seismic moment of the 2011 M w 9.0 Tohoku earthquake by using far-field coseismic displacements from 41 continuous GPS stations in Northeast Asia. In support of nearly 100 GPS campaign stations, we interpolate precise interseismic velocities at continuous GPS stations which are lacked of pre-seismic observations by using the Gaussian distance-based interpolation method, aiming to pursuiting more accurate post-seismic displacements. Then, we invert for the mantle viscosity and effective lithosphere thickness in the study area by employing nonlinear least squares fitting of the high signal-to-noise horizontal post-seismic displacements from 2.5 to 4.5 yr after the earthquake at 9 GPS stations distributed perpendicular to the fault plane of the earthquake, and the viscoelastic spherical Earth dislocation theory with modified fault slip model. The optimum solution of the inversion realizes the viscosity being 1.0× 1019 Pa s and the lithospheric thickness being 30 km. We find that the far-field post-seismic displacements caused by afterslip and mantle viscoelastic relaxation are approximately equal within 2.5 yr, and after 4.5 yr the cumulative effects of the latter component dominate the total far-field post-displacements. The result indicated that we cannot ignore the effects of mantle viscoelastic relaxation in the far field, even immediately after this earthquake. In addition, in the study of the far-field post-seismic displacements, we should take the signal-to-noise ratio of the GPS data into account with adequate observations to ensure the accuracy of the inversion. [ABSTRACT FROM AUTHOR]

Nowadays, vehicles have been increasingly adopted in mobile crowdsensing applications. Due to their predictable mobility trajectories, vehicles as participants bring new insight in improving the crowdsensing quality. The predictable mobility of vehicles provides not only the current locations of the vehicles, but also their future mobility trajectory. In this context, the existing participant recruitment solutions, which are mainly based on the current locations of the participants, cannot be directly used in vehicle-based mobile crowdsensing. Utilizing the predicted mobility trajectory of vehicles, this paper aims to propose efficient vehicle recruitment algorithms for mobile crowdsensing, so as to minimize the overall recruitment cost. Specifically, we study two mobility trajectory models of the vehicles, named deterministic and probabilistic models. We first prove that the vehicle recruitment problem under both models is NP-hard. Then, for the deterministic trajectory model, an efficient LP-relaxation-based heuristic algorithm is proposed, and an approximation ratio is analyzed. For the probabilistic trajectory model, we propose a greedy algorithm and analyze its performance with a guaranteed approximation ratio. Finally, we evaluate the performance of the proposed schemes through simulations. [ABSTRACT FROM PUBLISHER]

High-precision GPS data processing on Bernese has been employed to routinely resolve daily position solutions of GPS stations in the Crustal Movement Observation Network of China (CMONOC). The rank-deficient problems of the normal equation (NEQ) system and the network effect on the frame alignment of NEQs in the processing of CMONOC data on Bernese still present difficulties. In this study, we diagnose the rank-deficient problems of the original NEQ, review the efficiency of the controlled datum removal (CDR) method in filtering out the three frame-origin-related datum contents, investigate the reliabilities of the inherited frame orientation and scale information from the fixation of the GPS satellite orbits and the Earth rotation parameters in establishing the NEQ of the CMONOC network on Bernese, and analyze the impact of the network effect on the position time series of GPS stations. Our results confirm the nonsingularity of the original NEQ and the efficiency of the CDR filtering in resolving the rank-deficient problems; show that the frame origin parameters are weakly defined and should be stripped off, while the frame orientation and scale parameters should be retained due to their insufficient redefinition from the minimal constraint (MC) implementation through inhomogeneous and asymmetrical fiducial networks; and reveal the superiority of a globally distributed fiducial network for frame alignment of the reconstructed NEQs via No-Net-Translation (NNT) MC conditions. Finally, we attribute the two apparent discontinuities in the position time series to the terrestrial reference frame (TRF) conversions of the GPS satellite orbits, and identify it as the orbit TRF effect. [ABSTRACT FROM AUTHOR]

In this paper, two types of geodetic measurements, GRACE and GPS, are combined to study the vertical crustal deformation on the northeastern margin of the Tibetan Plateau. The GRACE and GPS derived results show that significant seasonal variations occur at 40 regional continuous GPS stations of the Crustal Movement Observation Network of China (CMONOC). The consistency between the seasonal variations in the GRACE and GPS data can be efficiently enhanced by decreasing the nonlinear deformation in the GPS time series with applying longer observation period. The vertical components of more than 78% of the total number of GPS stations exhibit correlations of more than 0.8 with respect to the corresponding GRACE components, and approximately 73% of the GPS vertical time series exhibit a significant root mean square reduction of approximately 40%, which increases to 60% when corresponding seasonal components derived from the GRACE measurements are subtracted. We consider that the vertical seasonal variations in the study area are caused by mass transfer related to hydrological loading, whereas the horizontal components are related to both mass transfer and other factors, such as the thermal elastic response of the GPS monuments and GPS data processing strategical deficits. These factors distinguish the main differences between the two measurements and exert larger influences in the eastward direction than in the northward direction, contributing to the total displacement. Finally, we use seasonal variations derived from the GRACE results to modify the vertical time series of corresponding GPS campaign stations to mitigate the influences of seasonal loading as much as possible in the dispersed time series. The results show that this modification can significantly reduce the scatter of campaign time series and improve the derived velocities uncertainties remarkably. [ABSTRACT FROM AUTHOR]

In this article, the size of the cavity combline filter is greatly reduced by using capacitively loaded disks and reentrant combline resonators. It has low loss, high Q quality factor and wide stopband. The feasibility of this method is analyzed theoretically. The characteristics of the structure are studied by simulations. The size of the fabricated filter is almost 50% of the size of the conventional cavity combline filter. The measured S parameters of the two filters are given. At 1575 MHz, which is the operating frequency of the global positioning system receiver antijamming antenna array system, the inserted loss of the improved filter is 0.702 dB. To minimize the interference from the Bei-Dou double star positioning system, at 1615 MHz, which is the operating frequency of this system, the out-of-band rejection of the improved filter at this frequency is 27.010 dB. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 910–913, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24191 [ABSTRACT FROM AUTHOR]

Mass redistribution within the Earth system deforms the surface elastically. Loading theory allows us to predict loading induced displacement anywhere on the Earth's surface using environmental loading models, e.g., Global Land Data Assimilation System. In addition, different publicly available loading products are available. However, there are differences among those products and the differences among the combinations of loading models cannot be ignored when precisions of better than 1 cm are required. Many scholars have applied these loading corrections to Global Navigation Satellite System (GNSS) time series from mainland China without considering or discussing the differences between the available models. Evaluating the effects of different loading products over this region is of paramount importance for accurately removing the loading signal. In this study, we investigate the performance of these different publicly available loading products on the scatter of GNSS time series from the Crustal Movement Observation Network of China. We concentrate on five different continental water storage loading models, six different non-tidal atmospheric loading models, and five different non-tidal oceanic loading models. We also investigate all the different combinations of loading products. The results show that the difference in RMS reduction can reach 20% in the vertical component depending on the loading correction applied. We then discuss the performance of different loading combinations and their effects on the noise characteristics of GNSS height time series and horizontal velocities. The results show that the loading products from NASA may be the best choice for corrections in mainland China. This conclusion could serve as an important reference for loading products users in this region. [ABSTRACT FROM AUTHOR]

Using global positioning system (GPS) observations of northeastern China and the southeast of the Russian Far East over the period 2012–2017, we derived an ITRF2014-referenced velocity field by fitting GPS time series with a functional model incorporating yearly and semiannual signals, linear trends, and offsets. We subsequently rotated the velocity field into a Eurasia-fixed velocity field and analyzed its spatial characteristics. Taking an improved multiscale spherical wavelet algorithm, we computed strain rate tensors and analyzed their spatial distribution at multiple scales. The derived Eurasia-referenced velocity field shows that northeastern China generally moved southeastward. Extensional deformation was identified at the Yilan–Yitong Fault (YYF) and the Dunhua–Mishan Fault (DMF), with negligible strike–slip rates. The principal strain rates were characterized by NE–SW compression and NW–SE extension. The dilation rates show compressional deformation in the southern segment of the YYF, northern end of the Nenjiang Fault (NJF), and southeast of the Russian Far East. We also investigated the impact of the 2011 Tohoku Mw 9.0 earthquake on the crustal deformation of northeastern China, generated by its post-seismic viscoelastic relaxation. The velocities generated by the post-seismic viscoelastic relaxation of the giant earthquake are generally orientated southeast, with magnitudes inversely proportional with the epicentral distances. The principal strain rates caused by the viscoelastic relaxation were also characterized by NW–SE stretching and NE–SW compression. The dilation rates show that compressional deformation appeared in the southern segment of the DMF and the YYF and southeast of the Russian Far East. Significant maximum shear rates were identified around the southern borderland between northeastern China and the southeast of the Russian Far East. Finally, we compared the multiple strain rates and the seismicity of northeastern China after the 2011 Tohoku earthquake. Our finding shows that the ML ≥ 4.0 earthquakes were mostly concentrated around the zones of high areal strain rates and shear rates at scales of 4 and 5, in particular, at the DMF and YYF fault zones. [ABSTRACT FROM AUTHOR]

The 2017 Jiuzhaigou Ms 7.0 earthquake occurred on the northeastern margin of the Tibetan Plateau, with no noticeable rupture surface recognized. We characterized the pre-seismic deformation of the earthquake from GPS (Global Positioning System) data at eight continuous and 73 campaign sites acquired over the 2009–2017 period. With respect to the Eurasian plate, the velocity field showed a noticeable decrease, from west of the epicenter of the Jiuzhaigou earthquake to the western edge of the Longmenshan fault, in the southeast direction. The total northwest west–southeast east shortening rate in the vicinity of the epicentral area was in the range of 1.5 mm/y to 3.1 mm/y. With a GPS velocity transect across the Huya fault (HYF), where the epicenter was located, we estimated the activity of the HYF, showing a dominant left-lateral slip rate of 3.3 ± 0.2 mm/y. We calculated strain rates using a spherical wavelet-based multiscale approach that solved for the surface GPS velocity according to multiscale wavelet basis functions while accounting for spatially variable spacing of observations. Multiscale components of the two-dimensional strain rate tensor showed a complex crustal deformation pattern. Our estimates of strain rate components at the scale of seven and eight revealed extensional strain rate on the northern extension of the HYF. The Jiuzhaigou earthquake occurred at the buffer zone between extensional and compressional deformation, and with significant maximum shear rates being 100–140 nanostrain/y. In addition, a maximum shear strain rate of 60–120 nanostrain/y appeared around the epicenter of the 2013 Ms 6.6 Minxian–Zhangxian earthquake. These findings imply that inherent multiscale strain rates could be separated to identify strain accumulation related to medium- and large-sized earthquakes. [ABSTRACT FROM AUTHOR]

• Three GRACE mascon solutions are fused to a unified solution in North China Plain. • Unified GRACE data reveal an accelerated groundwater depletion in 2013–2016. • Water table changes agree with the accelerated groundwater depletion. • Land subsidence in North China Plain was accelerated and expanded in 2013–2016. • This acceleration was caused by overexploitation in drought 2013–2016. As one of the most important agricultural bases in China, the North China Plain (NCP) has experienced serious groundwater depletion. However, estimates of groundwater depletion rates in NCP differ considerably from one another due to different datasets and methods used in the estimation. To get a better estimate of the groundwater depletion and to reveal the recent groundwater changes in NCP, we first merge Gravity Recovery and Climate Experiment (GRACE) mass concentration (mascon) solutions from different organizations and soil moisture from different land surface models to yield unified mascon solutions and soil moisture estimates. We then estimate the groundwater changes by subtracting the unified soil moisture and surface water storages in the major reservoirs in NCP from the unified mascon solutions. Results show that the groundwater storage in NCP depleted at a rate of 1.7 ± 0.1 cm/yr from 2004 to mid-2016 but this depletion accelerated to 3.8 ± 0.1 cm/yr from mid-2013 to mid-2016. Ground-based water table data show a consistent groundwater depletion rate (−3.9 ± 0.3 cm/yr from mid-2013 to mid-2016) with the GRACE results. We also analyze the land subsidence in NCP by using 116 Global Positioning System (GPS) sites and depict the accelerated land subsidence and expanded subsidence funnels since 2013, which is consistent with the groundwater depletion. All these point to a strong acceleration in groundwater depletion in NCP since mid-2013. Land surface model outputs suggest a precipitation decline from 2013 to 2016, which caused a decline in soil moisture content and surface water storage. This drought forced people to exploit more groundwater to compensate the surface water shortage and thereby led to the accelerated groundwater depletion. [ABSTRACT FROM AUTHOR]

Quantifying the present–day kinematics of southeastern Tibet is important for understanding the tectonic evolution of the Tibetan Plateau. In this study, we established a three–dimensional finite element model to estimate fault slip and strain rates in the southeastern Tibetan Plateau based on Global Navigation Satellite Systems (GNSS) observations. Our model yields an overall good fit to the GNSS velocity field with residuals of 0.83 mm/yr and 0.85 mm/yr for the east and north components, respectively, comparable to the uncertainties of 0.67 mm/yr and 0.61 mm/yr. The model–derived strike–slip rates of the Xiaojiang fault, Nanhua–Chuxiong fault, Qujiang fault, central segment of Red River fault, southeastern segment of Red River fault and Dien Bien Phu fault are 13.7 ± 0.7 mm/yr, 1.9 ± 0.6 mm/yr, 3.4 ± 1.1 mm/yr, 1.5 ± 0.5 mm/yr, 1.2 ± 0.4 mm/yr and 1.6 ± 0.4 mm/yr, respectively, which are consistent with previous geological results, implying that the short–term fault motions estimated from GNSS data can reflect the long–term fault slip in the southeastern Tibetan Plateau. The shear strain rate is localized along the Xiaojiang fault, which agrees with predictions of the tectonic extrusion model (i.e., the lateral extrusion of internally rigid blocks along strike-slip faults). Strain orientations in the western part of southeastern Tibetan Plateau are characterized by clockwise rotation. Comparison of the surface strain rates, crustal stress, and seismic anisotropy reveals general consistency between deformation of the surface and upper crust. The eastern part of southeastern Tibetan Plateau has small residuals, and the present–day crustal deformation can be explained by rigid block motion. However, the western part of the study area has relatively large residuals, implying that other processes, such as gravitational spreading, may influence deformation in the area. We propose a hybrid model that combines rigid block motion with continuum deformation to explain the contemporary crustal deformation of southeastern Tibetan Plateau. • We established a three-dimensional finite element model to analyze the fault slip and strain rates in southeastern Tibet. • We find good agreement between the GNSS and geologic slip rates in southeastern Tibetan Plateau. • Comparison of strain rate, stress, seismic anisotropy reveals consistency between deformation of surface and upper crust. [ABSTRACT FROM AUTHOR]