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251.
Lin Junshu Li Juzhang Fang Jinfu Institute of Geography CAS Beijing People''s Republic of China 《地理学报(英文版)》1997,(3)
IntroductionSolutionasakarstgeomorphologicalprocessinlandformdevelopmenthaslongbeenrecognized.Sincethekarstprocessesarealmostentirelysolution,thoughkarstlandformsarenotonlycausedbysolutionbutalsobyerosion,thecirculationandchemicalcompositionsofkarstun… 相似文献
252.
Chen Jianyao Wu Kai Institute of Geography CAS Beijing People''s Republic of China 《地理学报(英文版)》1997,(3)
I.IntroductionTheHuang-Huai-HaiPlaininNorthChinaisacrucialareainprovidingaboutone-fifthoftotalstatefood[4],anditisfacingaseriouswatershortageinrecentyearsduetotheexpansionofindustryandacontinuousdecreaseinprecipitation.Thestudyinsoil-plant-atmosphereconti… 相似文献
253.
Leng Shuying Zheng Du Institute of Geography CAS Beijing People''s Republic of China 《地理学报(英文版)》1997,(4)
I.LandDegradationDistributionandItsCharacteristicsThefarmingpastoraltransitionalregioninsemiaridlandofnorthernChinaisthemosttypicalregionoflanddegradation,andalsotheregionwithextensivelydevelopingsandydesertification.TheextentisfromHorqinSandyLandinth… 相似文献
254.
Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between th 相似文献
255.
In this paper,the Gutenberg-Richter model is used to generate seismic events.The events that satisfy the random distribution are also generated.With those events,the natural probability distribution of Load and Unload Response Ratio(LURR),which measures quantitatively the degree of instability of a nonlinear system,is discussed.The study is based on stress energy release,which is chosen as the response of nonlinear system F3.The comparative results from the observation catalogue and generating data are also studied.It is revealed that the natural probability of LURR is mostly stable when the sample number is sufficient.The lower the natural probability of LURR,the more the precursory is information it may contain.The influence of Y3 resulting from the sample number and the magnitude range of events is also discussed. 相似文献
256.
Taking the active fault network as the structural frame, the Chinese mainland and its periphery can be regarded as a system of "fault movement and seismogeny." By using the self-coupling method, preliminary study shows that the seismogenic system is a time-ordered dissipation system. The time order in the state far from equilibrium is established and maintained through mass and energy exchanges between the system and the surroundings. The evolution of the seismogenic system follows some properties of unbalanced phase change, namely, critical retard, bifurcation, entropy reduction, etc. 相似文献
257.
Zhou Cuiying Wang Hongwei Wang Mei and Zhang YuxiaSeismological Bureau of Shandong Province Jinan China Center for Analysis Prediction SSB Beijing China 《中国地震研究》1997,(4)
In order to solve the problem of early estimation of moderately strong aftershock duration time in an earthquake sequence,this study has been conducted.First,the definition of the strong aftershock has been given.It is pointed out that there is a difference in the strong aftershock duration time between the main shock type sequence and the strong earthquake swarm sequence.After dividing the three cases,i.e.,a strong aftershock duration time larger than 1 day,smaller than 1 day,and no strong aftershock occurred in a main shock type sequence by using the pattern recognition method,we gave the rough correlation relation between strong aftershock duration time and first large shock magnitude for two types of sequences.Finally,the judgment index and method of estimating strong aftershock duration times for different sequence types have been given. 相似文献
258.
Dong Ruishu Xiang Hongfa Guo Shunmin Ran Hongliu and Fu ChanghongInstitute of Geology SSB Beijing China Institute of Geophysics SSB Beijing China 《中国地震研究》1997,(4)
There have been 12 possible locations of the earthquakes occurring in the South Yellow Sea since 1505.In this paper,the location of the earthquake that occurred in 1505 has been determined by the collection of more historical data of the influenced field,referring the isoseismal data of earthquakes with the epicentral intensityⅨ and combining geophysical field data with tectonic condition,due to its great influence on seismic safety assessment of some significant engineering. 相似文献
259.
近年来的一些研究表明,由于地震前孕震区地下介质的电性结构的变化,将导致地磁短周期转换函数发生异常变化。通过对地震前后的地磁短周期转换函数的参数的计算、分析和研究,有可能提取出可靠的地震短临前兆异常(曾小苹等,1990)。为了进一步开展对该方法研究工作并使其在我区地震预测预报研究中得到应用,我们使用了静海台的地磁记录资料,分析计算了该台地磁短周期转换函数在地震前后的变化情况,确立了该方法应用天津地区地震预报的短临异常特征及指标,取得了较好的效果。 相似文献
260.
Sequence Stratigraphy of the Permian--Triassia Boundary Section of Changxing, Zhejiang, Southern China 总被引:1,自引:0,他引:1
Zhang Kexin Tong Jinnan Yin Hongfu Wu Shunbao China University of Geosciences Wuhan Hubei 《《地质学报》英文版》1997,71(1):90-103
Three third-order sequences and about one hundred high-frequency cycles or Milankovitchcycles within the Late Permian Changxingian to Early Triassic Griesbachian are identified in theMeishan Section of Changxing, Zhejiang Province, southern China, the candidate stratotype sec-tion of the global Permo-Triassic boundary, based on a detailed study of the biological,ecological and high-resolution allochthonous cyclic events, microfacies and depositional systems.Furthermore, the stacking pattern of the depositional systems across various Changxingian andGriesbachian sedimentary facies of the Lower Yangtze and the sequence stratigraphic frameworkare outlined with the Meishan section as the principal section. In this paper the habitat types offossil biota are applied to semiquantitative palaeobathymetry and the study of relative sea levelchanges. 相似文献