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Analysis of the common model error on velocity field under Colored noise model by GPS and InSAR: A case study in the Nepal and everest region

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Geodesy and Geodynamics 2022年第4期13卷 399-414页

作者： Wei Xu Gang Chen Kaihua Ding Defang Yang Yanfa Si Xiaoying Yang Qinghai Remote Sensing Center for Natural Resources Xining 810000China college of Marine Science and Technology China University of GeosciencesWuhan 430074China School of Geography and Information Engineering China University of GeosciencesWuhan 430074China Institute of geophysics and Geomatics China University of GeosciencesWuhan 430074China

The accuracy of the velocity field will be affected by the noise model and common mode errors through GPS time series analysis.In order to analyze the influence of these two factors on the accuracy of the velocity field,two kinds of data are used,including the three-year observation from 20 permanent GPS stations with high spatial correlation in the Everest,which is about 650 km from north to south and 1068 km from east to west,and three-year 80 ascending images and 141 descending images from sentinel-1A,which are processed by GAMIT/GLOBK software and Small Baseline Subset-Interferometric Synthetic Aperture Radar method(SBAS-InSAR),respectively.The vertical deformation rate is solved by time series analysis through a self-made adaptive algorithm.In the analysis,the linear change rate,period,half period coefficient,and residual sequence of all stations are solved by using James L.Davis periodic model.The noise type of residual sequence is analyzed by the power spectrum model.The spatio-temporal correlated noise,Common Mode Error(CME),is extracted by the Principal Component Analysis(PCA)and Karhunen-Loeve(KLE)methods.The results show that noises can be best described by“flicker noise+white noise”model.After the removal of CME,the R^(2) estimates of all stations are above 0.8,with RMS value of velocity field decreasing from 1.428 mm/yr to 1.062 mm/yr and 1.063 mm/yr to 0.815 mm/yr,in N and E directions,respectively,indicating that the influence of CME can't be ignored in the extraction of the high-precision velocity field in the Nepal and Everest region.

关键词： GPS time analysis SBAS-InSAR Power spectrum analysis PCA KLE CME

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Universal precursor seismicity pattern before locked-segment rupture and evolutionary rule for landmark earthquakes

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Geoscience Frontiers 2022年第3期13卷 22-34页

作者： Hongran Chen Siqing Qin Lei Xue Baicun Yang Ke Zhang Key Laboratory of Shale Gas and Geoengineering Institute of Geology and GeophysicsChinese Academy of SciencesChina Innovation Academy for Earth Science CASChina college of Earth and Planetary Sciences University of Chinese Academy of SciencesChina School of Resources and Civil Engineering Northeastern UniversityChina

Despite extensive investigations,no precursor patterns for reliably predicting major earthquakes have thus far been identified.Seismogenic locked segments that can accumulate adequate strain energy to cause major earthquakes are highly heterogeneous and low brittle.The progressive cracking of the locked segments with these properties can produce an interesting seismic phenomenon:a landmark earthquake and a sequence of smaller subsequent earthquakes(pre-shocks)always arise prior to another landmark earthquake within a well-defined seismic zone and its current seismic period.Applying a mechanical model,magnitude constraint conditions,and case study data of 62 worldwide seismic zones,we show that two adjacent landmark earthquakes reliably occur at the volume-expansion point and peak-stress point(rupture)of a locked segment;thus,the former is an identified precursor for the latter.Such a precursor seismicity pattern before the locked-segment rupture has definite physical meanings,and it is universal regardless of the focal depth.Because the evolution of landmark earthquakes follows a deterministic rule described by the model,they are predictable.The results of this study lay a firm physical foundation for reliably predicting the occurrence of future landmark earthquakes in a seismic zone and can greatly improve our understanding of earthquake generation mechanism.

关键词： Precursor Locked segment Volume-expansion point Peak-stress point Landmark earthquake

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Equatorial aurora: the aurora-like airglow in the negative magnetic anomaly

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National Science Review 2020年第10期7卷 1606-1615页

作者： Fei He Yong Wei Weixing Wan Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences college of Earth and Planetary Sciences University of Chinese Academy of Sciences

The most fantastic optical phenomena in the Earth’s upper atmosphere are the auroras. They are highly informative indicators of solar activity, geomagnetic activity, upper atmospheric structures and dynamics,and magnetospheric energetic particles. An area where the geomagnetic field differs significantly from the expected symmetric dipole, such as at the South Atlantic Anomaly, where the magnetic field intensity is low,gives rise to stronger precipitation of energetic particles into the upper atmosphere. Impact excitation and the subsequent airglow emissions exhibit aurora-like dynamic signatures. Nomenclatures of nonpolar aurora or equatorial auroras are similar to those used with the polar auroras owing to their similar excitation mechanisms. This paper provides an overview of the knowledge and the challenges concerning auroral activity at the South Atlantic Anomaly, or more generally, at the negative magnetic anomaly. We emphasize systematic investigation of the equatorial auroras to reveal the temporal and spatial evolution of the magnetic anomaly and the behaviour of energetic particles in near-Earth space.

关键词： aurora geomagnetic field South Atlantic Anomaly negative magnetic anomaly energetic particles

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Long-Term Reproducibility of SIMS Zircon U-Pb Geochronology

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Journal of Earth Science 2022年第1期33卷 17-24页

作者： Wenhao Zhao Qiuli Li Yu Liu Guoqiang Tang Xiaoxiao Ling Jiao Li Xianhua Li State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China college of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China

Secondary ion mass spectrometry(SIMS) zircon U-Pb dating has been widely used to confine the absolute ages of the magmatic or metamorphic events and to distinguish multiple events.Here,a data set consisting of the zircon standards dating data(~15 000 Ple?ovice and ~8 000 Qinghu items) accumulated for more than 8 years using the CAMECA IMS 1280 HR of the Institute of Geology and geophysics,Chinese Academy of Sciences(IGGCAS) is compiled to evaluate the long-term external reproducibility.With Ple?ovice zircon as the calibration standard and Qinghu zircon as an unknown sample,the analytical uncertainties for single-spot(n = 7 723) and session analyses(n = 691,with more than 7 single spot analyses in one session) are 2.6% and 0.9%(2 RSD,relative standard deviation),respectively.It means that single-spot U-Pb dating for a standard-level zircon sample could vary 5.2% at 95% confidence level,while the average value(n > 7) for each session may vary 1.8%.Thus,these values should be considered as the minimum uncertainty when comparing single spot and individual session analysis results for multiple dating works on a certain geological event.

关键词： zircon U-Pb dating SIMS uncertainty reproducibility

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Perspectives on the role of terrestrial ecosystems in the ‘carbon neutrality' strategy

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Science China Earth Sciences 2022年第6期65卷 1178-1186页

作者： Shilong PIAO Chao YUE Jinzhi DING Zhengtang GUO college of Urban and Environmental Sciences Peking UniversityBeijing 100871China Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing 100101China Institute of Soil and Water Conservation Northwest A&F UniversityYangling 712100China Institute of Geology and geophysics Chinese Academy of SciencesBeijing 100029China

The Chinese government has made a strategic decision to reach ‘carbon neutrality' before 2060. China's terrestrial ecosystem carbon sink is currently offsetting 7–15% of national anthropogenic emissions and has received widespread attention regarding its role in the ‘carbon neutrality' strategy. We provide perspectives on this question by inferring from the fundamental principles of terrestrial ecosystem carbon cycles. We first elucidate the basic ecological theory that, over the long-term succession of ecosystem without regenerative disturbances, the carbon sink of a given ecosystem will inevitably approach zero as the ecosystem reaches its equilibrium state or climax. In this sense, we argue that the currently observed global terrestrial carbon sink largely emerges from the processes of carbon uptake and release of ecosystem responding to environmental changes and, as such, the carbon sink is never an intrinsic ecosystem function. We further elaborate on the long-term effects of atmospheric CO_(2) changes and afforestation on China's terrestrial carbon sink: the enhancement of the terrestrial carbon sink by the CO_(2) fertilization effect will diminish as the growth of the atmospheric CO_(2) slows down, or completely stops, depending on international efforts to combat climate change, and carbon sinks induced by ecological engineering, such as afforestation, will also decline as forest ecosystems become mature and reach their late-successional stage. We conclude that terrestrial ecosystems have nonetheless an important role to play to gain time for industrial emission reduction during the implementation of the ‘carbon neutrality' strategy. In addition, science-based ecological engineering measures including afforestation and forest management could be used to elongate the time of ecosystem carbon sink service. We propose that the terrestrial carbon sink pathway should be optimized, by addressing the questions of ‘when' and ‘where' to plan afforestation projects, in order to effectively strengthen the terrestrial

关键词： Carbon neutrality Terrestrial ecosystem carbon sink CO_(2)fertilization effect Afforestation Carbon sink pathway

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Quantitative description of steam channels after steam flooding

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Science China(Technological Sciences) 2013年第6期56卷 1164-1168页

作者： ZHENG Qiang LIU HuiQing LI Fang WANG Qing WANG ChangJiu LU Chuan Key Laboratory for Petroleum Engineering of Ministry of Education China University of Petroleum college of geophysics and Information Engineering China University of Petroleum

Steam channeling is one of the main barriers for EOR after steam flooding.In order to enhance the oil recovery in steam flooded reservoirs,steam channel volumes should be precisely known.In this paper,a set of methods has been established in order to study steam channeling quantitatively by using dynamic data.Firstly,steam channeling wells are identified through curves of watercut and temperature.Then,considering the hysteresis phenomenon,channeling relations are identified with the correlation coefficients between injection wells and production wells under different conditions.Lastly,an analytic model,in which steam condensation,pressure and temperature are considered,is established to calculate the steam channel volumes.A production well named L31615 in some block in Henan Oilfield in China is systematically analyzed by using the method established.The whole block is further analyzed,and the distribution map of steam channels and the steam channel volumes are obtained.The results show that steam channeling does not only occur inside a well group,but also sometimes occurs between wells in different well groups.The calculation of the steam channel volumes provides a theoretical basis for bringing a remedial action like plugging into operation.

关键词：蒸汽驱通道定量描述原油采收率动态数据滞后现象相关系数蒸汽冷凝

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Experimental Research on Supercritical Carbon Dioxide Fracturing of Sedimentary Rock:A Critical Review

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Acta Geologica Sinica(English Edition) 2023年第3期97卷 925-945页

作者： ZHENG Bowen QI Shengwen LU Wei GUO Songfeng WANG Zan YU Xin ZHANG Yan Key Laboratory of Shale Gas and Geoengineering Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China college of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100029China

Supercritical carbon dioxide(ScCO_(2))fracturing has great advantages and prospects in both shale gas exploitation and CO_(2)storage.This paper reviews current laboratory experimental methods and results for sedimentary rocks fractured by ScCO_(2).The breakdown pressure,fracture parameters,mineral composition,bedding plane angle and permeability are discussed.We also compare the differences between sedimentary rock and granite fractured by ScCO_(2),ultimately noting problems and suggesting solutions and strategies for the future.The analysis found that the breakdown pressure of ScCO_(2)was reduced 6.52%–52.31%compared with that of using water.ScCO_(2)tends to produce a complex fracture morphology with significantly higher permeability.When compared with water,the fracture aperture of ScCO_(2)was decreased by 4.10%–72.33%,the tortuosity of ScCO_(2)was increased by 5.41%–70.98%and the fractal dimension of ScCO_(2)was increased by 4.55%–8.41%.The breakdown pressure of sandstone is more sensitive to the nature of the fracturing fluid,but fracture aperture is less sensitive to fracturing fluid than for shale and coal.Compared with granite,the tortuosity of sedimentary rock is more sensitive to the fracturing fluid and the fracture fractal dimension is less sensitive to the fracturing fluid.Existing research shows that ScCO_(2)has the advantages of low breakdown pressure,good fracture creation and environmental protection.It is recommended that research be conducted in terms of sample terms,experimental conditions,effectiveness evaluation and theoretical derivation in order to promote the application of ScCO_(2)reformed reservoirs in the future.

关键词： sedimentary rock supercritical carbon dioxide fracturing experiment breakdown pressure fracture parameters

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Impact history and origin of lunar meteorite Northwest Africa 15528

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Science China Earth Sciences 2023年第6期66卷 1399-1422页

作者： Runchuan LIU Huaiyu HE Thomas SMITH Hanqing YE Huapei WANG Xuhang ZHANG Fei SU Ziheng LIU Wei GUO Peng YANG Chuantong ZHANG Dingshuai Xue Ting CAO Jiannan LI Xuelong JIANG Ye HE Chao LU State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Institutes of Earth Science Chinese Academy of SciencesBeijing 100029China college of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Paleomagnetism and Planetary Magnetism Laboratory School of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074China State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi’an 710069China Institution of Meteorites and Planetary Materials Research Center Guilin University of TechnologyGuilin 541004China

No samples from the Moon’s far side have been returned to Earth.Thus,lunar meteorite study can deepen the understanding of the Moon’s far side(if we can identify which lunar meteorites came from the Moon’s far side).The Northwest Africa(NWA)15528 meteorite is a lunar feldspathic regolith breccia meteorite and we speculated it might originate from the Feldspathic Highlands Terrane(FHT)on the far side of the Moon.Here,we report detailed petrography,major and trace elements,and noble gas(He,Ne,and Ar)isotopes for the clasts and matrix,respectively.The results show that the NWA 15528 lunar meteorite contains diverse clasts,including anorthosite,granulite,basalt,and impact melt clasts.The coarse,wellcrystallized,uniform chemical composition minerals may come from intrusive plutonic rocks.Among the anorthosite clasts,the norite/olivine clasts originate from the deep lunar crust,whereas the other anorthosite clasts are from lunar highlands.The Sm concentrations in NWA 15528 were similar to those in the fourth group of Apollo 16 melt samples,demonstrating that NWA 15528 has a typical plagioclase highland meteorite composition.Compared with the Apollo sample data and remote sensing results,the chemical composition of NWA 15528 indicated strong affinities with the FHT area and ferroan anorthosite(FAN)material from the far side of the Moon.The noble gas isotopic composition of NWA 15528 is consistent with a binary mixture of solar wind and cosmogenic components;during stepwise pyrolytic extractions,we observed that the abundance of cosmogenic components decreased,whereas that of solar wind components increased with increasing temperature.The average cosmic-ray exposure(CRE)age of the matrix and granulite is 42±6 Ma,with a shielding depth in the same range of 10-20 g cm^(−2).The gas retention age of NWA 15528 is 2.14 Ga,and the antiquity age of NWA 15528 is(0.69-0.74)±0.2 Ga(considering 50%40Arm is 40Artrap)which indicates the different clasts of NWA 15528 are assembled after 0.69-0.74 Ga.

关键词： The Moon Regolith Meteorites Cosmic rays Solar wind Thermal histories Far side of the Moon

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Correlation analysis between the occurrence of epidemic in ancient China and solar activity

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Science China Earth Sciences 2023年第1期66卷 161-168页

作者： Si CHEN Yong WEI Xin’an YUE Kaihua XU Mingkun LI Wei LIN Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China college of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Beijing Institute of Genomics Chinese Academy of Sciencesand China National Center for BioinformationBeijing 100101China Center for Excellence in Animal Evolution and Genetics Chinese Academy of SciencesKunming 650223China

As the globe has witnessed the pandemic,epidemic diseases exert a strong impact on human beings and ecosystems.Since the Sun is the primary energy source of the Earth,some scientific pioneers attempted to search for the discernible relation between solar activity and the incidence of epidemics.In this study,the periodic changes and trends of ancient Chinese epidemic data were analyzed in comparison with those of sunspot numbers,a solar activity proxy.The results show that the epidemic and solar activity changes are in good agreement to a certain extent,especially during the Gleissberg and the de Vries cycles.The wavelet coherence shows that the frequency of the epidemic data and sunspot numbers are highly associated.In addition,results from the ensemble empirical mode decomposition illustrate consistent variations in low-frequency decompositions.This study has important implications for further understanding of the potential impact of solar activity on Earth’s biosphere,the underlying mechanism of which needs further exploration.

关键词： Epidemic Ancient China Solar activity Spectrum analysis

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3-D multi-parameter type traveltime tomography in a spherical coordinate frame: comparison of double and triple class simultaneous inversions

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Earthquake Science 2018年第2期31卷 62-74页

作者： Chaoying Bai Jiayu Sun Xingwang Li Stewart Greenhalgh Department of geophysics College of Geology Engineering and Geomatics Chang'an University Institute of Computational geophysics Chang'an University Department of Geosciences King Fahd University of Petroleum and Minerals

It is now common practice to perform simultaneous traveltime inversion for the velocity field and the reflector geometry in reflection/refraction tomography, or the velocity field and the hypocenter locations in regional earthquake tomography, but seldom are all three classes of model parameters updated simultaneously. This is mainly due to the trade-off between the different types of model parameters and the lack of different seismic phases to constrain the model parameters. Using a spherical-coordinate ray tracing algorithm for first and later（primary reflected） arrival tracing algorithm in combination with a popular linearized inversion solver, it is possible to simultaneously recover the three classes of model parameters in regional or global tomographic studies. In this paper we incorporate the multistage irregular shortest-path ray tracing algorithm（in a spherical coordinate system） with a subspace inversion solver to formulate a simultaneous inversion algorithm for triple model parameters updating using direct and later arrival time information.Comparison tests for two sets of data（noise free and added noise） indicate that the new triple-class parameter inversion algorithm is capable of obtaining nearly the same results as the double-class parameter inversion scheme. Furthermore,the proposed multi-parameter type inversion method is not sensitive to a modest level of picking error in the traveltime data, and also performs well with a relatively large uncertainty in earthquake hypocentral locations. This shows it to be a feasible and promising approach in regional or global tomographic applications.

关键词： simultaneous triple model parameten inversion reflector geometry hypocenter location subspace inversion multistage irregular shortest-path ray tracing

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