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Advances in Polar Science 2019年第1期30卷 70-75页

作者： LI Yan LU Yang ZHANG Zizhan SHI Hongling XI Hui State key laboratory of geodesy and Earth's dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

To estimate basal water storage beneath the Antarctic ice sheet, it is essential to have data on the three-dimensional characteristics of subglacial lakes. We present a method to estimate the water depth and surface area of Antarctic subglacial lakes from the inversion of hydraulic potential method. Lake Vostok is chosen as a case study because of the diverse and comprehensive measurements that have been obtained over and around the lake. The average depth of Lake Vostok is around 345±4 m. We estimated the surface area of Lake Vostok beneath the ice sheet to be about 13300±594 km^2. The lake consists of two sub-basins separated by a ridge at water depths of about 200–300 m. The surface area of the northern sub-basin is estimated to be about half of that of the southern basin. The maximum depths of the northern and southern sub-basins are estimated to be about 450 and 850 m, respectively. Total water volume is estimated to be about 4658±204 km^3. These estimates are compared with previous estimates obtained from seismic data and inversion of aerogravity data. In general, our estimates are closer to those obtained from the inversion of aerogravity data than those from seismic data, indicating the applicability of our method to the estimation of water depths of other subglacial lakes.

关键词： three-dimensional features Lake Vostok hydraulic potential subglacial water storage

Crustal structure of the northeastern Tibetan plateau,the Ordos block and the Sichuan basin from ambient noise tomography

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Earthquake Science 2010年第5期23卷 465-476页

作者： Yong Zheng Yingjie Yang Michael H. Ritzwoller Xiufen Zheng Xiong Xiong Zuning Li key laboratory of dynamic geodesy Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Department of Physics University of Colorado Boulder CO 80303 USA Institute of Geophysics China Earthquake Administration Beijing 100081 China Earthquake Administration of Fujian Province Fuzhou 350003 China

We apply ambient noise tomography to significant seismic data resources in a region including the northeastern Tibetan plateau, the Ordos block and the Sichuan basin. The seismic data come from about 160 stations of the provincial broadband digital seismograph networks of China. Ambient noise cross-correlations are performed on the data recorded between 2007 and 2009 and high quality inter-station Rayleigh phase velocity dispersion curves are obtained between periods of 6 s to 35 s. Resulting Rayleigh wave phase velocity maps possess a lateral resolution between 100 km and 200 kin. The phase velocities at short periods （〈20 s） are lower in the Sichuan basin, the northwest segment of the Ordos block and the Weihe graben, and outline sedimentary deposits. At intermediate and long periods （〉25 s）, strong high velocity anomalies are observed within the Ordos block and the Sichuan basin and low phase velocities are imaged in the northeastern Tibetan plateau, reflecting the variation of crustal thickness from the Tibetan plateau to the neighboring regions in the east. Crustal and uppermost mantle shear wave velocities vary strongly between the Tibetan plateau, the Sichuan basin and the Ordos block. The Ordos block and the Sichuan basin are dominated by high shear wave velocities in the crust and uppermost mantle. There is a triangle-shaped low velocity zone located in the northeastern Tibetan plateau, whose width narrows towards the eastern margin of the plateau. No low velocity zone is apparent beneath the Qinling orogen, suggesting that mass may not be able to flow eastward through the boundary between the Ordos block and the Sichuan basin in the crust and uppermost mantle.

关键词： phase velocity Ordos block ambient noise tomography crustal structure

Ce Anomalies of the Yangtze Region,South China,through the Ordovician and Silurian Transition

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Journal of Earth Science 2009年第6期20卷 941-948页

作者：严德天张丽琴李双建 key laboratory of Tectonics and Petroleum Resources of Ministry of Education China University of GeosciencesWuhan Institute of Geology and Geophysics Chinese Academy of Sciences School of geodesy and Geomatics Wuhan University key laboratory of Geospace Environment & geodesy of Ministry of Education Wuhan University Petroleum Exploration and Production Institute of SINOPEC

Systematic Ce anomalies for whole-rock have been obtained from the shale-dominated, continuous, and pelagic sedimentary sequences spanning the Ordovician/Silurian （O/S） boundary at the Tieshui （铁水） of Xiushan （秀山）, Chongqing （重庆）, South China. Ce anomalies across the O/S boundary are recognized in three intervals, Wufeng （五峰）, Guanyinqiao （观音桥） and Longmaxi （龙马溪）. The calculated Ce/Ce＊ values of Wufeng Formation range from 0.84 to 0.96 （avg. 0.90）. In the Guanyinqiao Formation, the values of calculated Ce/Ce＊ range from 0.73 to 0.85 （avg. 0.79）. The Ce/Ce＊ values of uppermost Longmaxi Formation range from 0.87 to 0.96 （avg. 0.91）. All along the section, the magnitude of the Ce anomaly is always negative, but is more significant in the Guanyinqiao Formation. The relatively higher Ce/Ce＊ values in the Wufeng and Longmaxi shales are likely to be due to the sediments deposited under rather reducing conditions. The Ce anomaly apparently does play some regular roles in the anoxic events that accompany prominent mass extinctions, and this work provides new data of critical importance for constraining models on the end-Ordovician anoxic events and mass extinctions.

关键词： Ce anomaly redox mass extinction Ordovician/Silurian boundary Yangtze platform.

Mapping coalmine goaf using transient electromagnetic method and high density resistivity method in Ordos City, China

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geodesy and Geodynamics 2016年第5期7卷 340-347页

作者： Guiju Wu Guangliang Yang Hongbo Tan The key laboratory of Earthquake geodesy Institute of Seismology China Earthquake Administration

The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect coalmine goaf areas based on rock resistivity. The data processing using wavelet transform, three point smoothing, RES2 DINV and Maxwell processing software to obtain 2D resistivity structure. The results showed that the layers with maximum resistivity values（30e33 U m on Line 1, 30e31 U m on Line 2, 32e40 U m on Line3） are founded at station 1e7, and 14e20 on Line 1,13e18 on Line 2, and 8e13 and 16e20 on Line 3 which is predicted as goaf layer, and the minimum resistivity values（20e26 U m of TEM, 45e75 U m of HDRM） at the other layers. This resistivity difference was caused by the geology and characteristics of the study area which is located close by the cleugh with rich coal, so the goaf area distinguishable with aquifer layer and coal seam. The results were also significant accidents and serious destruction of ecological environment.

关键词： Transient electromagnetic method High density resistivity method Coalmine goaf areas Geotechnical Electrical

Performance analysis of a new baseline-based SS-Y extensometer

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geodesy and Geodynamics 2018年第5期9卷 418-423页

作者： Linbin Wu Zhaosheng Nie key laboratory of Earthquake geodesy Institute of SeismologyChina Earthquake Administration

In order to solve the problems in the observation with the SS-Y extensometer, such as background noise and discontinuity of earth tide curve, this paper proposed to improve the stability of the instrument and the smoothness of the earth tide curve by improving the baseline structure of the instrument. In this study, a new φ20*1.2 invar tube was introduced in replacement of the existing φ6 invar rod as the baseline of the instrument and compared with the existing φ6 invar rod on the instrument’s linearity,sensitivity and other indexes. Firstly, the SS-Y extensometers using φ6 invar rod and cp20*1.2 invar tube were tested. Test results were then calculated, and accuracy errors of the instruments based on the two baselines were obtained. Finally, their accuracy errors and earth tide curves were compared. Results showed that, compared with the extensometer based on the existing φ6 invar rod, the extensometer based on the new φ20*1.2 invar tube was superior in performance, with linearity error reducing to 0.495% from 0.937%, sensitivity increasing to 68.65 mV/μm from 65.46 mV/μm, and earth tide curve growing more stable and continuous.

关键词： Invar tube Extensometer Ground deformation Background noise Earth tide

Seasonal features of topside scale height based on COSMIC measurements

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geodesy and Geodynamics 2017年第5期8卷 328-334页

作者： Fanfan Su Jian Lin Fuying Zhu Yiyan Zhou Jian Yang Liangchen Hu key laboratory of Earthquake geodesy Institute of SeismologyChina Earthquake Administration

Plasma scale height is an important parameter of topside ionosphere and contains information about ionospheric physics and dynamic. We investigated the seasonal features of vertical scale height with the electron density profiles from COSMIC. We found that vertical scale height around 660 km at middle latitudes generally has larger values in winter than in summer and had similar structures at March Equinox and September Equinox no matter daytime or nighttime. Bands of large vertical scale height appear at night around ±36° magnetic latitude in all seasons except summer for low solar activity, and mostly appear in winter for moderate solar activity. Vertical scale height in the middle latitudes generally has smaller values for moderate solar activity than that for low solar activity around 660 km, and has smaller values in the daytime than at night.

关键词： Scale heightTopside ionosphereCOSMICElectron density

Construction of lake bathymetry from MODIS satellite data and GIS from 2003 to 2011

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Chinese Journal of Oceanology and Limnology 2014年第3期32卷 720-731页

作者：严翼肖飞杜耘 University of Chinese Academy of Sciences Institute of geodesy and Geophysics Chinese Academy of SciencesKey Laboratory for Environment and Disaster Monitoring and Evaluation

In recent years, sedimentation conditions in Dongting Lake have varied greatly because of signifi cant changes in runoff and sediment load in the Changjiang(Yangtze) River following the construction of Three Gorges Dam. The topography of the lake bottom has changed rapidly because of the intense exchange of water and sediment between the lake and the Changjiang River. However, time series information on lake-bottom topographic change is lacking. In this study, we introduced a method that combines remote sensing data and in situ water level data to extract a record of Dongting Lake bottom topography from 2003 to 2011. Multi-temporal lake land/water boundaries were extracted from MODIS images using the linear spectral mixture model method. The elevation of water/land boundary points were calculated using water level data and spatial interpolation techniques. Digital elevation models of Dongting Lake bottom topography in different periods were then constructed with the multiple heighted waterlines. The mean root-mean-square error of the linear spectral mixture model was 0.036, and the mean predicted error for elevation interpolation was-0.19 m. Compared with fi eld measurement data and sediment load data, the method has proven to be most applicable. The results show that the topography of the bottom of Dongting Lake has exhibited uneven erosion and deposition in terms of time and space over the last nine years. Moreover, lake-bottom topography has undergone a slight erosion trend within this period, with 58.2% and 41.8% of the lake-bottom area being eroded and deposited, respectively.

关键词： Dongting Lake geomorphy time-series maps remote sensing MODIS data water level

Estimated Green's function extracted from superconducting gravimeters and seismometers

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Earthquake Science 2011年第2期24卷 143-150页

作者： Xiangfang Zeng Zhongwen Zhan Yong Zheng Mengcheng National Geophysical Observatory School of Earth and Space Sciences University of Science and Technology of China China Seismological laboratory California Institute of Technology Pasadena CA 91125 USA 3 CAS Key Laboratory of Dynamical Geodesy Institute of Geodesy and Geophysics Wuhan 430077 China CAS key laboratory of dynamical geodesy Institute of Geodesy and Geophysics Wuha'n 430077 China

Estimated Green’s function （EGF） between stations has been extracted from ambient seismic noise, direct surface wave and coda waves. It is also confirmed by laboratory experiments on ultrasonics and theoretical derivations assuming diffusive wave field, equi-partition of modes or random sources on an enclosed surface. This method provides a new approach to study the crust and mantle structure at regional scale, continental scale and global scale. Following the achievements with seismometer records, the records of infrasonic station, hydrophone and microphone were also used to obtain the EGFs of different wave fields. Since superconducting gravimeter is a better long period instrument than regular seismometer, EGF at longer period is expected to be obtained with the cross correlation of gravity data. In this paper, we will show the EGFs extracted by cross-correlations between the superconducting gravimeters and the seismometers. Both the travel times and dispersion curves obtained from different data types are consistent. The result shows that it is possible to retrieve the deep structure by the cross correlation of gravity data.

关键词： superconducting gravimeter noise cross-correlation estimated Green’s function

Insight into Urban Faults by Wavelet Multi-Scale Analysis and Modeling of Gravity Data in Shenzhen,China

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Journal of Earth Science 2018年第6期29卷 1340-1348页

作者： Chuang Xu Haihong Wang Zhicai Luo Hualiang Liu Xiangdong Liu MOE key laboratory of Fundamental Physical Quantities Measurement School of PhysicsHuazhong University of Science and Technology School of geodesy and Geomatics Wuhan University key laboratory of Geospace Environment and geodesy Ministry of EducationWuhan University China Water Resources Beifang Investigation Design and Research Co.Ltd.

Urban faults in Shenzhen are potential threats to city security and sustainable development. In consideration of the importance of the Shenzhen fault zone, the author provide a detailed interpretation on gravity data model. Bouguer gravity covering the whole Shenzhen City was calculated with a 1-km resolution. Wavelet multi-scale analysis（MSA） was applied to the Bouguer gravity data to obtain the multilayer residual anomalies corresponding to different depths. In addition, 2D gravity models were constructed along three profiles. The Bouguer gravity anomaly shows an NE-striking high-low-high pattern from northwest to southeast, strongly related to the main faults. According to the results of MSA, the correlation between gravity anomaly and faults is particularly significant from 4 to 12 km depth. The residual gravity with small amplitude in each layer indicates weak tectonic activity in the crust. In the upper layers, positive anomalies along most of faults reveal the upwelling of high-density materials during the past tectonic movements. The multilayer residual anomalies also yield important information about the faults, such as the vertical extension and the dip direction. The maximum depth of the faults is about 20 km. In general, NE-striking faults extend deeper than NW-striking faults and have a larger dip angle.

关键词： urban faults Bouguer gravity anomaly wavelet multi-scale analysis gravity modeling Shenzhen

Indexing the relationship between polar motion and water mass change in a giant river basin

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Science China Earth Sciences 2018年第8期61卷 1065-1077页

作者： Suxia LIU Shanshan DENG Xingguo MO Haoming YAN key laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research(IGSNRR) Chinese Academy of Sciences University of Chinese Academy of Sciences (UCAS) College of Resources and Environment Sino-Danish College State key laboratory of geodesy and Earth’s dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences

Previous studies on the relationship between polar motion and water mass change have mainly concentrated on the excitation of polar motion via global terrestrial water storage changes(TWSC). In view of the uneven distribution of global terrestrial water storage, the relationship between regional water mass change and polar motion needs to be further explored owing to the lack of documented results. In addition, given the uncertainty in the estimation of TWSC, it is required to develop appropriate indices to describe water mass change from different perspectives. The Amazon River basin(referred to Amazon hereafter), containing the world's largest river, located at around the 90°W longitude, is selected as the study area. Water vapor flux, precipitation, runoff and TWSC are selected as the indices of water mass changes to reveal the relationship between polar motion and water mass change in this giant basin. The Mann-Kendall(M-K) method, the accumulated anomaly analysis method and the curvature method are used to identify the abrupt change points; the least squares method is used to estimate the trends,and the Fast Fourier Transform(FFT) and the Ensemble Empirical Mode Decomposition(EEMD) are used to perform a periodic analysis, for all the above indices. It is shown that, of all the indices from 1948 to 2011, water vapor flux is the most closely related index to polar motion. In detail, precipitation and water vapor flux contain beat periods of polar motion; water vapor flux,precipitation and polar motion have a common M-K test abrupt change point(occurring in ca. 1968) at the 0.05 significance level; water vapor flux has a similar accumulated anomaly curve with that of polar motion; and water vapor flux is more highly correlated with polar motion than most other indexes. It is found, just like global TWSC, the χ2 component of the excitation via water vapor flux and water storage change in the Amazon follows that of observed polar motion; χ1 does not follow. However,

关键词： Polar motion the Amazon River Basin Location of Vapor-based Inter Tropical Convergence Zone(LVITCZ) Terrestrial water storage changes(TWSC) Water vapor flux