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Earth orientation parameters from VLBI determined with a Kalman filter

Geodesy and Geodynamics 2017年第6期8卷 396-407页

作者： Maria Karbon Benedikt Soja Tobias Nilsson Zhiguo Deng Robert Heinkelmann Harald Schuh gfz german research centre for geosciences Telegrafenherg A 17 Potsdam Germany Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA Technical University of Berlin Strafe des 17. Juni 135 Berlin Germany

This paper introduces the reader to our Kalman filter developed for geodetic VLBI（very long baseline interferometry） data analysis. The focus lies on the EOP（Earth Orientation Parameter） determination based on the Continuous VLBI Campaign 2014（CONT14） data, but also earlier CONT campaigns are analyzed. For validation and comparison purposes we use EOP determined with the classical LSM（least squares method） estimated from the same VLBI data set as the Kalman solution with a daily resolution. To gain higher resolved EOP from LSM we run solutions which yield hourly estimates for polar motion and dUTl = Universal Time（UT1）-Coordinated Universal Time（UTC）. As an external validation data set we use a GPS（Global Positioning System） solution providing hourly polar motion results.Further, we describe our approach for determining the noise driving the Kalman filter. It has to be chosen carefully, since it can lead to a significant degradation of the results. We illustrate this issue in context with the de-correlation of polar motion and nutation.Finally, we find that the agreement with respect to GPS can be improved by up to 50% using our filter compared to the LSM approach, reaching a similar precision than the GPS solution. Especially the power of erroneous high-frequency signals can be reduced dramatically, opening up new possibilities for highfrequency EOP studies and investigations of the models involved in VLBI data analysis.We prove that the Kalman filter is more than on par with the classical least squares method and that it is a valuable alternative, especially on the advent of the VLBI2010 Global Observing System and within the GGOS frame work.

关键词： VLBI Earth rotation CONT14 Kalman filter Data analysis Least squares GPS

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Thermospheric Density Anomaly in the Polar Cap Region During Geomagnetic Storms

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地学前缘 2009年第S1期16卷 118-118页

作者： H.Luehr Helmholtz centre Potsdam GFZGerman Research Centre For Geosciences

The heating of the ionosphere-thermosphere system at high latitudes is a rather common phenomenon in the space climate.During geomagnetic storm time, Joule-heating enhances at high altitudes.The heating generates atmospheric upwelling causing large changes in thermospheric composition and hence in the total mass density.The CHAMP satellite with its complementary payload and long-duration mission provides an excellent dataset for studying the storm-related heating of the upper atmosphere.Based on the four-year accelerometer measurements,density enhancements in polar cap region are observed

关键词： thermospheric density geomagnetic storms polar cap heating

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Complex dynamics of repeating and river-blocking landslides in Jiangda during 2018

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Earthquake Science 2021年第1期34卷 3-14页

作者： Wenying Li Yong Zhang Yueyi Xu Xujun Zheng Rongjiang Wang Jinrong Su Guixi Yi Qinghua Huang School of Earth and Space Sciences Peking UniversityBeijing 100871China gfz german research Center for geosciences Potsdam 14461Germany Sichuan Earthquake Agency Chengdu 61004China

Two large landslides successively blocked the Jinsha River at the same location in Jiangda Village on October 10 and November 3,2018,respectively.The dynamic processes and possible interactions of the two landslides need to be studied to better understand the physical processes involved,and to provide information on future disaster mitigation.We investigated their force histories and sliding directions by inverting regional broadband seismograms.The scale of the October landslide was approximately three times that of the November event.The October event revealed a particularly strong deceleration force,which may have been caused by a collision between the sliding mass and ground surface.In contrast,the November event had a relatively weaker deceleration force,indicating that it may have been gradually stopped by the landslide dam formed during the October landslide.The sliding directions of the two landslides differed significantly in terms of both horizontal and vertical directions,indicating a change in their sliding surfaces.We conclude that unconsolidated materials at the top of the October landslide continued sliding along a curved slope during the November event.From our seismic models of dynamic processes,both the October landslide and local background may have affected and even changed a subsequent landslide’s mechanism.

关键词： landslides waveform inversion friction non-tectonic earthquake inversion

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Seismic prompt gravity strain signals in a layered spherical Earth

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Earthquake Science 2023年第5期36卷 341-355页

作者： Shenjian Zhang Rongjiang Wang Xiaofei Chen Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhen 518055China Helmholtz Center Potsdam GFZ German Research Center for GeosciencesD-14473 PotsdamGermany Guangdong Provincial Key Laboratory of Geophysical High-resolution Imaging Technology Southern University of Science and TechnologyShenzhen 518055China Shenzhen Key Laboratory of Deep Offshore Oil and Gas Exploration Technology Southern University of Science and TechnologyShenzhen 518055China

Seismic waves generated by an earthquake can produce dynamic perturbations in the Earth’s gravity field before the direct arrival of P-waves.Observations of these so-called prompt elasto-gravity signals by ground-based gravimeters and broadband seismometers have been reported for some large events,such as the 2011 M_(W)9.1 Tohoku earthquake.Recent studies have introduced prompt gravity strain signals(PGSSs)as a new type of observable seismic gravity perturbation that can be used to measure the spatial gradient of the perturbed gravity field.Theoretically,these types of signals can be recorded by indevelopment instruments termed gravity strainmeters,although no successful detection has been reported as yet.Herein,we propose an efficient approach for PGSSs based on a multilayered spherical Earth model.We compared the simulated waveforms with analytical solutions obtained from a homogeneous half-space model,which has been used in earlier studies.This comparison indicates that the effect of the Earth’s structural stratification is significant.With the help of the new simulation approach,we also demonstrated how the PGSSs depend on the magnitude of the seismic source.We further conducted synthetic tests estimating earthquake magnitude using gravity strain signals to demonstrate the potential application of this type of signal in earthquake early warning systems.These results provide essential information for future studies on the synthesis and application of earthquake-induced gravity strain signals.

关键词： gravity strain synthetic seismogram earthquake early warning system

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基于SWARM双星观测的场向电流的经度变化

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地球物理学报 2019年第2期62卷 447-461页

作者：王慧郑志超 Hermann Luehr 武汉大学电子信息学院空间物理系武汉430072 gfz german research Center for geosciences

本文利用SWARM A和C双星高精度的矢量磁场数据研究了不同季节高纬地区场向电流(FACs)随地磁经度和地方时的变化情况.研究发现:在南北半球,FACs存在明显的经度变化,南半球FACs的变化强度大约是北半球的1.2～3.2倍.利用潮汐谱分析法我们发... 详细信息

本文利用SWARM A和C双星高精度的矢量磁场数据研究了不同季节高纬地区场向电流(FACs)随地磁经度和地方时的变化情况.研究发现:在南北半球,FACs存在明显的经度变化,南半球FACs的变化强度大约是北半球的1.2～3.2倍.利用潮汐谱分析法我们发现FACs中占主导的非迁移潮汐分量为DW2和D0.在春秋和夏季半球,DW2波更为明显.D0波可用太阳光照的经度变化来解释,向阳侧靠近磁极的经度带比远离磁极的经度带有更强的太阳光照射.DW2波则与地磁场强度和地磁倾角等因素有关.全球电离层与热层模型计算的FACs中D0波占主导,且中性风和对流电场对D0波的贡献几乎相当.

关键词：场向电流太阳光照地磁倾角

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DEEP Neoarchean Subduction Indicated by Ultra-high Pressure TiO_(2)(Ⅱ) Inclusion in Ophiolitic Podiform Chromitite Block in Mélange, Central(Taihang) Orogenic Belt, North China

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Acta Geologica Sinica(English Edition) 2021年第S1期95卷 85-87页

作者： Tim KUSKY WANG Lu Paul ROBINSON Richard WIRTH HUANG Yang State Key Lab for Geological Processes and Mineral Resources Center for Global TectonicsChina University of GeosciencesWuhan 430074China Helmholtz Center Potsdam german research centre for geosciences gfz D-14473 PotsdamGermany

Understanding crust-mantle recycling through time,especially into the Archean,is crucial for understanding how the crust has grown from the mantle,and in turn how crustal material returned to the mantle alters the mantle reservoir.Recycling of crustal material,such as C-H-O-NS-P are especially important for understanding how processes such as subduction,melting,volcanism,and the release of volatiles have regulated climate and life on Earth over billions of years.

关键词： Archean tectonics ophiolitic mélange ultrahigh-pressure minerals suduction carbon cycle

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Hydromechanical behaviors of andesite under different stress states during fluid injection

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第4期13卷 727-744页

作者： Miao He Qi Li Xiaying Li Liang Xu Michael Kühn State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China Fluid Systems Modelling Section GFZ German Research Centre for GeosciencesPotsdamGermany Institute of Earth and Environmental Science University of PotsdamPotsdamGermany

Water reinjection into the formation is an indispensable operation in many energy engineering practices.This operation involves a complex hydromechanical(HM)coupling process and sometimes even causes unpredictable disasters,such as induced seismicity.It is acknowledged that the relative magnitude and direction of the principal stresses significantly influence the HM behaviors of rocks during injection.However,due to the limitations of current testing techniques,it is still difficult to comprehensively conduct laboratory injection tests under various stress conditions,such as in triaxial extension stress states.To this end,a numerical study of HM changes in rocks during injection under different stress states is conducted.In this model,the saturated rock is first loaded to the target stress state under drainage conditions,and then the stress state is maintained and water is injected from the top to simulate the formation injection operation.Particular attention is given to the difference in HM changes under triaxial compression and extension stresses.This includes the differences in the pore pressure propagation,mean effective stress,volumetric strain,and stress-induced permeability.The numerical results demonstrate that the differential stress will significantly affect the HM behaviors of rocks,but the degree of influence is different under the two triaxial stress states.The HM changes caused by the triaxial compression stress states are generally greater than those of extension,but the differences decrease with increasing differential stress,indicating that the increase in the differential stress will weaken the impact of the stress state on the HM response.In addition,the shear failure potential of fracture planes with various inclination angles is analyzed and summarized under different stress states.It is recommended that engineers could design suitable injection schemes according to different tectonic stress fields versus fault occurrence to reduce the risk of injection-induced seismicity.

关键词： Water reinjection Stress state Hydromechanical(HM)coupling Injection-induced seismicity Numerical modeling

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Field report:Sailing around the exhumed roots of the Mesozoic Patagonian paleo-accretionary wedge(Diego de Almagro Island,Chile)

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Geoscience Frontiers 2018年第5期9卷 1591-1594页

作者： Samuel Angiboust Jesus Munoz Institut de Physique du Globe de Paris Sorbonne Paris CitéUniversity Paris DiderotCNRSF-75005ParisFrance gfz german research centre for geosciences D-14473PotsdamGermany Carrera de Geología Universidad Andres BelloSazie2119SantiagoChile

We undertook a boat expedition to explore the geological framework of a very remote, lesser-known island, in the Chilean Patagonia: the Diego de Almagro Island(latitude S51°330'). This uninhabited, ca.400 km^2 Island is one of the very rare exposures of the Mesozoic accretionary subduction complex along the Chilean margin. Unstable weather, strong winds, steep topography, and very dense vegetation make an on-land mission difficult. Careful preparation based on high-resolution satellite images is advised to optimize shore access and minimize risks of injury. Despite a relatively important degree of regional reequilibration of metamorphic assemblages due to sluggish exhumation through the forearc crust, our results have shown that the island is composed of a nappe stack of ocean-floor derived slivers of metasedimentary units that exhibit very different pressure-temperature-time paths during burial by subduction under the Chilean margin and subsequent exhumation. These rocks are witness to a complex thermal evolution of the subduction zone between Jurassic and Cretaceous times from granulite facies to blueschist facies conditions as well as multiple episodes of accretion at ca. 35 -40 km in depth for almost100 Ma over the Mesozoic era.

关键词： Patagonia Accretionary wedge Blueschists Subduction Chile

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树脂柱串联法分离地质样品中Sr-Nd-U

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岩矿测试 2023年第1期42卷 102-113页

作者：骆正骅李超赖正王晨羽郭玉龙段知非徐娟杨守业海洋地质国家重点实验室(同济大学) 上海200092 同济大学海洋与地球科学学院上海200092 gfz german research centre for geosciences Earth Surface GeochemistryTelegrafenbergPostdam 14473Germany

Sr、Nd、U等同位素体系被广泛应用于地球表生过程中年代测定及物源示踪等研究,高效地分离这些同位素体系,对于推广这些同位素方法的应用具有重要现实意义。若要同时分析地质样品中Sr、Nd、U三种元素的同位素,现有方法往往需要消解两份样... 详细信息

Sr、Nd、U等同位素体系被广泛应用于地球表生过程中年代测定及物源示踪等研究,高效地分离这些同位素体系,对于推广这些同位素方法的应用具有重要现实意义。若要同时分析地质样品中Sr、Nd、U三种元素的同位素,现有方法往往需要消解两份样品,一份用于Sr-Nd而另一份用于U的分离提纯。这种方法不但增加了样品用量,而且需要多次蒸干溶液转换介质,既延长了分离流程也增加了样品被污染的风险。为了提高样品利用率和分析效率,本文通过将树脂柱串联改进了分离流程,提出一种仅需消解一份样品,便可同时提取Sr、Nd、U三种元素的新方法。本方法中Sr的分离采用Sr特效树脂,包含Nd在内的稀土元素(REE)的分离采用AG50W-X8树脂,U的分离采用UTEVA特效树脂。实验中将三种树脂柱串联,采用3mol/L硝酸淋洗液淋洗,同步进行平衡树脂、上样、洗杂志,避免了蒸干操作。分离后的淋出液使用电感耦合等离子体质谱仪(ICP-MS)测试元素含量。结果表明:U的回收率接近99.9%,Sr的回收率超过90%,Nd的回收率超过80%;同时三种树脂柱串联的分离流程,主要基体元素(K、Ca、Na、Ba、Fe、Rb等)的去除率均超过99%,降低了对Sr、Nd、U高精度同位素分析的干扰;REE中的Sm则可以通过后续使用Ln树脂等进一步去除。此外,本文还交换了Sr特效树脂和UTEVA树脂的位置,比对两种不同串联顺序对分离结果的影响,结果表明两种树脂柱串联顺序对目标元素的分离并无显著影响。使用该方法可以有效地实现Sr、Nd、U的分离,在减少操作步骤的同时节省约一半的样品用量,提高了同位素分析效率。

关键词： Sr Nd U 串联树脂柱回收率同位素分离电感耦合等离子体质谱法

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4D seismic monitoring of small CO2 injection - Results from the Ketzin pilot site(germany)

4D seismic monitoring of small CO2 injection - Results from ...

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Harmonising Rock Engineering and the Environment—12th ISRM International Congress on Rock Mechanics

作者： 2-Storage,Potsdam,germany 2-Storage,Potsdam,germany C.Juhlin A.Kashubin N.Juhojuntti 2-Storage,Potsdam,germany 2-Storage,Potsdam,germany gfz german research centre for geosciences Centre for CO Uppsala University Department for GeosciencesUppsalaSweden Uppsala University now at Schlumberger Cambridge Research CentreCambridgeUK

1 THE KETZIN SITE The geological storage of CO is debated as one option to reduce greenhouse gas emissions and to mitigate the severe consequences of climate change.Geophysical monitoring of storage operations is a key component assuring the safety of the reservoir and providing essential observations enabling to simulate and predict reservoir behaviour during ongoing injection and storage.Commercial CO storage has been operational at gas field sites like Sleipner and In-Salah for several years,where time-lapse seismic surveys were able to image the stored CO,amounting to several million tons in the resepective reservoirs(Michael et al.,2010).

关键词： case studies field measurements monitoring

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