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Dynamics of thinning and destruction of the continental cratonic lithosphere: Numerical modeling

Science China Earth Sciences 2018年第7期61卷 823-852页

作者： Mingqi LIU Zhonghai LI Key laboratory of computational geodynamics College of Earth and Planetary Sciences University of Chinese Academy of Sciences Institute of Geology Chinese Academy of Geological Sciences

Thinning of the cratonic lithosphere is common in nature, but its destruction is not. In either case, the mechanisms for both thinning and destruction are still widely under debate. In this study, we have made a review on the processes and mechanisms of thinning and destruction of cratonic lithosphere according to previous studies of geological/geophysical observations and numerical simulations, with specific application to the North China Craton(NCC). Two main models are suggested for the thinning and destruction of the NCC, both of which are related to subduction of the oceanic lithosphere. One is the "bottom-up" model, in which the deeply subducting slab perturbs and induces upwelling from the hydrous mantle transition zone(MTZ). The upwelling produces mantle convection and erodes the bottom of the overriding lithosphere by the fluid-meltperidotite reaction. Mineral compositions and rheological properties of the overriding lithospheric mantle are changed, allowing downward dripping of lithospheric components into the asthenosphere. Consequently, lithospheric thinning or even destruction occurs. The other is the "top-down" model, characterized by the flat subduction of oceanic slab beneath the overriding cratonic lithosphere. Dehydration reactions from the subducting slab would significantly hydrate the lithospheric mantle and decrease its rheological strength. Then the subduction angle may be changed from shallow to steep, inducing lateral upwelling of the asthenosphere. This upwelling would heat and weaken the overriding lithospheric mantle, which led to the weakened lithospheric mantle dripping into the asthenosphere. These two models have some similarities, in that both take the subducting oceanic slab and relevant fluid migration as the major driving mechanism for thinning or destruction of the overriding cratonic lithosphere. The key difference between the two models is the effective depth of the subducting oceanic slab. One is stagnation and flattening in t

关键词：岩石圈数字建模动力学动态模型大陆脱水反应应用可行性岩流圈

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Recent advances of computing coseismic deformations in theory and applications

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Earthquake Science 2014年第2期27卷 217-227页

作者： Wenke Sun Key laboratory of computational geodynamics University of Chinese Academy of Sciences

This paper reviews the recent advances in computing coseismic deformations,and their contributions to seismology and geodesy. At first,an overview on the history of the dislocation theory development is given in the introduction section. Then,emphasis are given on some new developments through few examples in the following sections,such as the new dislocation theory for a 3D Earth model,a new computing scheme on coseismic deflection change of vertical,the relation of dislocation Love number and the conventional Love numbers,the application of dislocation theory applied in satellite gravity observations,the coseismic deformations observed by GRACE,and a new method to determine dislocation Love numbers by GRACE. Furthermore,some advanced theoretical and cases studies are introduced to illustrate how dislocation theory is important in interpret geodetic data,or invert seismic slip for co- and post-seismic processes,using seismic and geodetic data. Final remarks are given in the last section,with discussions,conclusions,comments on existing problems,and expected methods to solve them.

关键词： Dislocation theory Coseismic deformations Earthquake Displacement Gravity Modern geodesy

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Characteristics of gravity signal and loading effect in China

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Geodesy and geodynamics 2015年第4期6卷 280-285页

作者： Yi Shuang Sun Wenke Key laboratory of computational geodynamics University of Chinese Academy of Sciences

The complex geographical environment in China makes its gravity signals *** work gives a comprehensive representation and explanation in secular trend of gravity change in different regions,the key features of which include positive trend in inner Tibet Plateau and South China and negative trend in North China plain and high mountain Asia（HMA）.We also present the patterns of amplitudes and phases of annual and semiannual *** mechanism underlying the semiannual period is explicitly *** displacement in three directions expressed in terms of geo-potential spherical coefficients and load Love numbers are given.A case study applied with these equations is *** results show that Global Positioning System（GPS） observations can be used to compare with Gravity Recovery and Climate Experiment（GRACE） derived displacement and the vertical direction has a signal-noise-ratio of about one order of magnitude larger than the horizontal directions.

关键词： Gravity change Loading effect Gravity Recovery and Climate Experiment (GRACE)Load love number Global Positioning System (GPS) Seasonal variation Gravity trend in China Comparison of GRACE and GPS

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3D MHD simulation of the double-gradient instability of the magnetotail current sheet

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Science China(Technological Sciences) 2018年第9期61卷 1364-1371页

作者： DUAN AiYing ZHANG Huai LU Hao Yu Key laboratory of computational geodynamics University of Chinese Academy of Sciences State Key laboratory of Space Weather Chinese Academy of Sciences School of Space and Environment Beihang University

Flapping motion of the current sheet(CS) is an important physical process in the Earth's magnetotail. The magnetic doublegradient model, which includes both the instability and wave modes, offers a reasonable explanation for the exciting and propagation of the flapping wave. In this paper, we apply an advanced numerical magnetohydrodynamic(MHD) scheme(conservation element and solution element(CESE)-MHD) to simulate the magnetic double-gradient instability in an idealized current sheet that mimics the magnetotail configuration. We initialize the simulations with a numerically relaxed magnetotail equilibrium, in which the normal component of the magnetic field has a tailward gradient. It is confirmed in our simulation that the instability develops in the current layer. The growth rate of the instability yielded from the simulation is very close to the prediction of theory, with a relative deviation of only ten percent. The results demonstrate that the CESE-MHD scheme is very powerful in numerical study of the double-gradient mechanism of the CS flapping mode, and can be used for further investigations of the flapping motion in more realistic CS configurations.

关键词：不稳定性坡度模拟 MHD 水流 3D 物理过程相对偏差

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Theories and applications of earthquake-induced gravity variation:Advances and perspectives

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Earthquake Science 2023年第5期36卷 376-415页

作者： He Tang Wenke Sun Key laboratory of computational geodynamics College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China State Key laboratory of Geodesy and Earth’s Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430077China

Earthquake-induced gravity variation refers to changes in the earth’s gravity field associated with seismic *** recent years,development in the theories has greatly promoted seismic deformation research,laying a solid theoretical foundation for the interpretation and application of seismological gravity *** terrestrial gravity measurements continue to play a significant role in studies of interseismic,co-seismic,and post-seismic gravity field *** instance,superconducting gravimeter networks can detect co-seismic gravity change at the sub-micro Gal *** the same time,the successful launch of satellite gravity missions(e.g.,the Gravity Recovery and Climate Experiment or GRACE)has also facilitated applied studies of the gravity variation associated with large earthquakes,and several remarkable breakthroughs have been *** progress in gravity observation technologies(e.g.,GRACE and superconducting gravimetry)and advances in the theories have jointly promoted seismic deformation studies and raised many new research *** example,superconducting gravimetry has played an important role in analyses of episodic tremor,slow-slip events,and interseismic strain patterns;the monitoring of transient gravity signals and related theories have provided a new perspective on earthquake early warning systems;the mass transport detected by the GRACE satellites several months before an earthquake has brought new insights into earthquake prediction methods;the use of artificial intelligence to automatically identify tiny gravity change signals is a new approach to accurate and rapid determination of earthquake magnitude and ***,many significant breakthroughs have been made in recent years,in terms of the theory,application,and observation *** article summarizes the progress,with the aim of providing a reference for seismologists and geodetic researchers studying the phenomenon of gravity variation,advances in

关键词： earthquake-induced gravity variation seismic dislocation theory time-varying gravity satellite gravity missions pre-P gravity signals superconducting gravimetry

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Modeling seismic wave propagation in heterogeneous medium using overlap domain pseudospectral method

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Earthquake Science 2008年第1期21卷 46-57+108页

作者：严九鹏王彦宾 Beijing 100871 China laboratory of computational geodynamics Department of Geophysics School of Earth and Space Sciences Pe-king University laboratory of computational geodynamics Department of Geophysics School of Earth and Space Sciences Pe-king University

Pseudospectral method is an efficient and high accuracy numerical method for simulating seismic wave propaga- tion in heterogeneous earth medium. Since its derivative operator is global, this method is commonly considered not suitable for parallel computation. In this paper, we introduce the parallel overlap domain decomposition scheme and give a parallel pseudospectral method implemented on distributed memory PC cluster system for modeling seismic wave propagation in heterogeneous medium. In this parallel method, the medium is decomposed into several subdomains and the wave equations are solved in each subdomain simultaneously. The solutions in each subdomain are connected through the transferring at the overlapped region. Using 2D models, we compared the parallel and traditional pseudospectral method, analyzed the accuracy of the parallel method. The results show that the parallel method can efficiently reduce computation time for the same accuracy as the traditional method. This method could be applied to large scale modeling of seismic wave propagation in 3D heterogeneous medium.

关键词： overlap domain decomposition scheme Fourier pseudospectral method parallel computation seismic wavefield

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Numerical analysis on thermal conductivity of poly-mineral rock

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Earthquake Science 2010年第3期23卷 223-232页

作者： Huimin Jing Xiangwei Yu Huai Zhang Yaolin Shi laboratory of computational geodynamics Graduate University of Chinese Academy of Sciences Beijing 100049 China

In order to explore the thermal conductivity of the natural poly-mineral rock,numerical tests of rock models with randomly-distributed components were conducted and compared with each *** designed Monte Carlo method was adopted to ingratiate the requirement of the random characteristics of grain size and the grains＇spatial *** requirement was fulfilled by clustering the randomly generated unstructured tetrahedral elements in full three *** rocks are consisted of randomly distributed crystal particles or intergranular *** primary results verify that the thermal conductivity of the rock is strongly sensitive to the ingredients＇ volume fraction and their spatial ***,we proved that,in order to reduce the measurement error to a reasonable range,the numerical specimen must be large enough or include sufficient number of mineral *** numerical test results are in accordance with a variety of empirical formulas which are currently employed in petrology.

关键词： thermal conductivity poly-mineral numerical test finite element method

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Thermal structure about southwest sub-basin of South China Sea

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Earthquake Science 2011年第5期24卷 427-436页

作者： Lin Meng Jian Zhang laboratory of computational geodynamics The Graduate University of the Chinese Academy of Sciences Beijing 100049 China

There are some factors, such as the topographic relief, sedimentary thickness and thermal conductivity, magmatic activity and thermal cooling, influencing the seafloor heat flow and the evolution of lithosphere structure in southwest sub-basin （SWSB）, South China Sea. On the base of the geological structure characteristic of SWSB this paper will discuss some other factors including thermal anomaly area, dike produced by magma intrusion and lithosphere relief, by modeling and calculating. Calculating results indicate partial areas where temperature is higher than vicinity in the lithosphere, which we call thermal anomaly here containing thermal anomaly area and dike in this paper, could decrease heat flow below, increase above, and gradually increase to two sides; heat flow in upwelling parts of lithosphere is usually higher than sinking parts, and in the middle is of a gradual transition.

关键词： southwest sub-basin (SWSB) thermal anomaly field heat flow dike lithosphere relief

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New research progress on the ultrastructure of tectonically deformed coals

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Progress in Natural Science:Materials International 2009年第11期19卷 1455-1466页

作者： Yiwen Ju,Xiaoshi Li laboratory of computational geodynamics,College of Earth Science,Graduate University of Chinese Academy of Sciences,Beijing 100049,China laboratory of computational geodynamics College of Earth Science Graduate University of Chinese Academy of Sciences Beijing 100049 China

The structure of tectonically deformed coals shows some characteristics and regulations on the ultra-scale when influenced by different factors such as temperature,pressure and directional *** of the macromolecular structure may induce changes in the nano-scale pore structure,which are very important for gas adsorption and *** geological impact of different mechanisms of deformation on different types of ultrastructure of tectonically deformed coals is not only of significance as a topic for scientific research, but also in studying environments of metamorphism-deformation at differing metamorphic *** research is also very important in studying the accumulation and occurrence conditions of coalbed methane gas,mechanisms of coal and gas outbursts,predictions of coalbed methane resources and dangers of coal and gas *** paper analyzes current research,within China and other countries, in the ultrastructure of tectonically deformed *** research includes(1) structural models of tectonically deformed coals;(2) the relationship between ultrastructure and stress;(3) the structure of tectonically deformed coals and its strain *** results are also based on our own experiments including vitirnite reflectance(Ro,max),X-ray diffraction(XRD) and nuclear magnetic resonance (NMR(CP/MAS + TOSS)).We discuss the important effects of the structure of tectonically deformed coals and their physical properties,and then point out some problems concerning the research progress of tectonically deformed coals.

关键词： Tectonically deformed coals Ultrastructure Pore structure Tectonic stress Strain environment

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Virtual ChuanDian--A parallel numerical modeling of Sichuan-Yunnan regional strong earthquake activities: Model construction and parallel simulation

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Science China Earth Sciences 2009年第10期52卷 1585-1598页

作者： ZHANG Huai1, WU ZhongLiang1,2, ZHANG DongNing2, LIU Jie2, WANG Hui2, YAN ZhenZhen1,2 & SHI YaoLin11 laboratory of computational geodynamics, Graduate University of Chinese Academy of Sciences, Beijing 100049, China 2 Institute of Geophysics, Chinese Earthquake Administration, Beijing 100081, China laboratory of computational geodynamics Graduate University of Chinese Academy of Sciences Beijing China Institute of Geophysics Chinese Earthquake Administration Beijing China

Reasonable use of mathematical modeling and numerical simulation of regional earthquake activities has attracted more and more attentions in realistic seismicity studies in recent years. The inherent nature of their attendant multi-scale properties, from either the temporal or the spatial direction, necessitates the use of the cutting-edge massive parallel data processing techniques. Our study here is focused on the model construction and numerical simulation of the regional stress evolution after large earthquake sequences along the fault zones in Sichuan and Yunnan areas, using large-scale parallel finite element approximations with tens of millions of unstructured meshes on the distributed systems. The objective of our study is to provide a state-of-the-art model and a large-scale numerical simulation platform, on which estimation of the risk of large earthquake triggering sequences can be carried out in a middle or long-term time scale with realistic data and constrains inputted from field observation and geological survey.

关键词： Sichuan-Yunan area seismic processing parallel simulation initial stress field

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