Analysis of the tidal gravity observations in Three Gorges reservoir area

The comparative observations of the tidal gravity in Three Gorges reservoir area, recorded with the LCR-ET20 gravimeter from Institute of Geodesy and Geophysics, Chinese Academy of Sciences and the DZW-9 gravimeter from Institute of Seismology, China Earthquake Administration, are introduced. High-accuracy tidal gravity pa-rameters in this area are obtained, and the scale factor of the DZW-9 gravimeter is also estimated at a value of ?(756.06±0.05)×10?8 m?s?2V?1. The observed residuals of the corresponding instruments are investigated. Nu-merical results indicate that the long-term drift of the DZW-9 gravimeter appears a linear characteristic, and the observed accuracy is of the same order comparing with that of the LCR-ET20 gravimeter. The results given in the paper can provide with an effective reference model of the tidal gravity correction to the ground based and space geodesy.     

Heterogeneous transition dynamic equations and the self-organized origin of the nesting rhythmic beddings in Panzhihua lithosomes

Dynamic equations were developed for heterogeneous phase-transition in a system of coupled nucleation, growth and ripening. Based on these equations, a self-organized origin of small-scale nesting rhythmic beddings in Pahzhihua lithosomes was investigated and the results showed that the beddings could be formed by the cross supersaturated nucleation-crystallization of augite and feldspar successively. This process could be implemented by coupling with supersaturated nucleation, Ostwald ripening, component diffusion and the primary grain diffusion under a proper temperature gradient. The slightly intensive supersaturated nucleation and Ostwald ripening occurring in Panzhihua lithosomes may relate closely to the mineral components such as V-Ti-Maanetite.     

Topographic effects on seismic response of long-span rigid-frame bridge under SV seismic wave

Seismic ground motions of two neighboring mountains and the free surface between them are calculated under the SV seismic waves with three different incident angles. The results are then taken as the inputs of multi-point seismic excitations for the foundation of a long-span bridge built over the valley in the analysis considering the integrated influence of traveling wave and topography. On the basis of a dynamic analytical method, a finite element model is created for the seismic responses of a four-span rigid-frame bridge of 440 m. The pier-top displacement and the pier-bottom internal force of the bridge are calculated. Then the results are compared with those considering traveling-wave effect only. The conclusions can serve as a seismic design reference for the structures located on the complex mountain topography.     

山东及邻区地壳介质剪切波分裂研究

采用山东地震台网记录到的近场源地震波形数据,基于剪切波分裂研究,获得山东地区多个台站的剪切波分裂参数。研究结果表明,快剪切波偏振优势方向反映了该地区构造应力空间分布特征,CHD台和LIS台显示出两个优势偏振方向,揭示山东地区地壳介质各向异性受到区域背景应力及局部断裂构造的双重制约。     

新疆天山南部构造区不同时段小地震目录完整性分析

依据天山地区地质构造、运动强度和历史地震活动的差异性,将南部天山地区划分为南天山东段和南天山西段两个构造区.考虑到新疆台网建设的区域差异性和时间的阶段性,在对两个构造区不同震级下限地震频度时间特征分析的基础上,研究了各构造区不同时段的G-R关系和震级分布特征,并运用Z检验方法对各区不同时段小地震目录差异的显著性进行了分析,进而评估了两个构造区1970年以来不同时段的小地震目录完整性,为区域地震活动性研究中地震目录的合理运用提供参考依据.     

Deblending of Simultaneous-source Seismic Data using Fast Iterative Shrinkage-thresholding Algorithm with Firm-thresholding

In this paper, an improved algorithm is proposed to separate blended seismic data. We formulate the deblending problem as a regularization problem in both common receiver domain and frequency domain. It is suitable for different kinds of coding methods such as random time delay discussed in this paper. Two basic approximation frames, which are iterative shrinkage-thresholding algorithm (ISTA) and fast iterative shrinkage-thresholding algorithm (FISTA), are compared. We also derive the Lipschitz constant used in approximation frames. In order to achieve a faster convergence and higher accuracy, we propose to use firm-thresholding function as the thresholding function in ISTA and FISTA. Two synthetic blended examples demonstrate that the performances of four kinds of algorithms (ISTA with soft- and firm-thresholding, FISTA with soft- and firm-thresholding) are all effective, and furthermore FISTA with a firm-thresholding operator exhibits the most robust behavior. Finally, we show one numerically blended field data example processed by FISTA with firm-thresholding function.     

Intra-seasonal variation of the Kuroshio southeast of Taiwan and its possible forcing mechanism

The intra-seasonal variation of the Kuroshio southeast of Taiwan has been studied using satellite data and a numerical model. Superimposed with the main stream of the Kuroshio, two intra-seasonal signals are revealed in the study region. The fluctuation with a period of 1–6 months results from offshore eddies. The westward propagating cyclonic eddies can reduce or reverse the northward flow east of the Kuroshio between 121° and 123° E, but only slightly touch the core velocity of the Kuroshio. The fluctuation with a period of 2–4 weeks is only significant between Taiwan and the Lan-Yu Island (the low-velocity region). Different mechanisms are responsible for the fluctuation in the low-velocity region in different seasons. In winter, the change of negative wind stress curl in the northeastern South China Sea modulates the circulation southeast of Taiwan, while the typhoon-induced intense wind is responsible for the current fluctuation in summer.     

地震空间分布非空网格数的统计分布及地震活动增强-平静的定量检测l

以华北地区1980——2010年资料为例,以单位边长的网格覆盖研究区,考察中小地震空间分布非空网格数的变化．网格尺度足够小则非空网格数趋于该时段的地震数,网格尺度足够大则非空网格数为1．实际资料显示,当空间网格尺寸大于0.5deg;之后,对结果稳定性的影响逐渐减弱．中小地震空间分布非空网格数的变化与ldquo;背景rdquo;地震活动的空间扩展（增强）或收缩（平静）有关．不同网格尺寸条件下的非空网格数有基本一致的变化趋势,可能间接反映了区域应力的短时扰动或起伏．小地震有更高的丛集特性,随着震级下限的提高,不同网格尺寸非空网格数之间差异逐渐变小．华北地区小震活动非空网格数的频次分布符合统计正态分布,因而给定置信概率、依据正态分布密度函数可计算非空网格数的ldquo;正常rdquo;分布范围,超出此范围的数据可视为异常．统计显示,就华北地区而言,中小地震非空网格数ldquo;平静rdquo;型异常的预测效率最低,ldquo;增强rdquo;型异常具有最高的报警对应率,而同时考虑ldquo;增强rdquo;及ldquo;平静rdquo;的异常判据则具有最高的预报评分．这也意味着,华北中强地震前以ldquo;增强rdquo;型的中小地震活动异常为主．研究结果还显示,小地震时空活动格局的改变与后续中强地震似乎具有更强的统计关联特性．      

Effects of uranium on hydrocarbon generation of hydrocarbon source rocks with type-III kerogen

Organic-inorganic interaction exists universally and is important in the process of mineral resources formation.It is the essential reason why organic oil,gas,coal and inorganic uranium coexist,accumulate,and mineralize in the same sedimentary basins.Hydrocarbon-generating simulation experiment was conducted using low-mature hydrocarbon source rock containing kerogen type III with uranium(UO2CO3 solution)added to study the effects of uranium on the hydrocarbon generation of hydrocarbon source rocks.Experiment results show that uranium can enhance the yield of gas hydrocarbon,promote the total gas output,and increase the total hydrocarbon production(mass or volume).Uranium may lower the hydrocarbon generation threshold temperature and lead to the generation of liquid hydrocarbon in the relative low temperature of hydrocarbon source rock.Uranium can enhance the yield of saturated hydrocarbon,promote the low molecular weight hydrocarbons generating,and in turn increase the content of CH4 and the content of dry gas of the generated hydrocarbons.Uranium is one of the potential inorganic accelerating factors of the immature hydrocarbons.