Simulation of normal distributed smooth fields by Karhunen-Loéve expansion in combination with kriging

Simulation of multigaussian stochastic fields can be made after a Karhunen-Loéve expansion of a given covariance function. This method is also called simulation by Empirical Orthogonal Functions. The simulations are made by drawing stochastic coefficients from a random generator. These numbers are multiplied with eigenfunctions and eigenvalues derived from the predefined covariance model. The number of eigenfunctions necessary to reproduce the stochastic process within a predefined variance error, turns out to be a cardinal question. Some ordinary analytical covariance functions are used to evaluate how quickly the series of eigenfunctions can be truncated. This analysis demonstrates extremely quick convergence to 99.5% of total variance for the 2nd order exponential (‘gaussian’) covariance function, while the opposite is true for the 1st order exponential covariance function. Due to these convergence characteristics, the Karhunen-Loéve method is most suitable for simulating smooth fields with ‘gaussian’ shaped covariance functions. Practical applications of Karhunen-Loéve simulations can be improved by spatial interpolation of the eigenfunctions. In this paper, we suggest interpolation by kriging and limits for reproduction of the predefined covariance functions are evaluated.     

Simulation of normal distributed smooth fields by Karhunen-Loéve expansion in combination with kriging

Simulation of multigaussian stochastic fields can be made after a Karhunen-Loéve expansion of a given covariance function. This method is also called simulation by Empirical Orthogonal Functions. The simulations are made by drawing stochastic coefficients from a random generator. These numbers are multiplied with eigenfunctions and eigenvalues derived from the predefined covariance model. The number of eigenfunctions necessary to reproduce the stochastic process within a predefined variance error, turns out to be a cardinal question. Some ordinary analytical covariance functions are used to evaluate how quickly the series of eigenfunctions can be truncated. This analysis demonstrates extremely quick convergence to 99.5% of total variance for the 2nd order exponential (‘gaussian’) covariance function, while the opposite is true for the 1st order exponential covariance function. Due to these convergence characteristics, the Karhunen-Loéve method is most suitable for simulating smooth fields with ‘gaussian’ shaped covariance functions. Practical applications of Karhunen-Loéve simulations can be improved by spatial interpolation of the eigenfunctions. In this paper, we suggest interpolation by kriging and limits for reproduction of the predefined covariance functions are evaluated.     

100Ma——塔里木盆地演化的重要周期

运用沉积盆地波动分析方法对塔里木盆地典型井的周期分析表明，塔里木盆地在其地质历史时期１００Ｍａ的周期是很明显的，自寒武纪以来共经历了４个完整的周期，每一完整周期都由正相位和负相位两个半周期所组成，而第三纪为第Ⅴ个周期的正相位阶段。该周期控制了盆地内的沉积与剥蚀的过程及成藏旋回，并至少控制了古生代的反转构造。对沉积与剥蚀过程的控制作用表现在周期波正相位和负相位分别对应于沉积期和剥蚀期；对含油气系统的控制作用表现在：第Ⅰ个周期波构成以早古生代地层为主体的含油气系统，第Ⅱ个周期波至第Ⅳ个周期波构成以晚古生代至中生代地层为主体的含油气系统，第Ⅴ个周期的正相位阶段构成以新生代地层为主体的含油气系统；对反转构造的控制作用表现在：正相位Ⅰ（寒武纪—早奥陶世）和正相位Ⅱ（晚泥盆世晚期—晚石炭世早期）为伸展构造体制，负相位Ⅰ（中奥陶世—晚泥盆世早期）与负相位Ⅱ（晚石炭世晚期—早二叠世早期）为挤压构造体制。塔里木盆地演化具有１００Ｍａ周期的原因与古天山洋、古昆仑洋及特提斯洋的Ｂ型俯冲触发的地幔羽的上升流及地块的拼贴导致的地幔羽的休眠状态息息相关，从而周期性地控制了塔里木盆地内的沉积与剥蚀过程、成藏旋回及反转构造。     

任意圆弧形凸起地形中隧洞对入射平面SH波的影响

借助辅助函数的思想， 采用波函数展开法给出了圆弧形凸起地形中隧洞对入射平面SH波影响问题的一个解析解．数值结果表明，凸起地形中隧洞的存在以及隧洞大小，对凸起地形表面运动，以及凸起地形中的隧洞的动应力集中均具有显著影响．      

HVSR prospecting in multi-layered environments: An example from the Tyrnavos Basin (Greece)

The Tyrnavos Basin (Central Greece) is an E-W trending graben bordered by two major antithetic sets of right-stepping dip-slip normal faults that began forming during Middle Pleistocene as a consequence of the N-S extension which affected the whole Aegean Region. This Quaternary structure is superimposed on the Pliocene-Early Pleistocene NW-SE trending Larissa Basin, approximately 700–800 m deep. Seismic activity is instrumentally well documented within and surrounding the investigated area. Based on structural, morphotectonic and palaeoseismological data, several structures previously characterised as active faults have been investigated by applying the HVSR method. This method is commonly used to map the thickness of sedimentary layers in a basin based on the variation of the fundamental 1-D frequency. The polyphased structural evolution and the consequently complex geological setting do not allow for the contouring of a unique continuous surface. We therefore developed a new interpretation technique for statistically significant HVSR peaks, in order to obtain 2-D sections that can be interpreted in a seismic-like fashion. We applied this technique across the major active faults bordering the basin. The results confirm their occurrence at depth and document the important vertical component of displacement.     

3-D rheologic model of earthquake preparation (II): Strain field and its applications

Introduction Based on the elastic theory of the hard inclusion (Dobrovolskii, 1991), we developed an inclusion theory of rheologic medium, and applied the results of bulk-strain field of a rheologic inclusion model to explain the spatial-temporal evolution process of earthquake precursors (SONG, et al, 2000). In the former paper (SONG, et al, 2003), we derived the viscoelastic displacement field of the rheologic inclusion model on the basis of the analytic expression of displacement field o…     

中国西北盆山地区地壳结构及其演化

根据新疆及其它相关地学断面所获资料，论述了中国西北盆山构造地区的地壳结构，已有资料表明，在中国西北盆山地区，山脉和盆地具有明显不同的地壳结构，它们的地壳厚度不同，表现为山区地壳厚，具有明显的山根：盆地区地壳厚度小，同时地壳分层和各层的组分也有所差异，这些地壳本身结构性的差异，以及它们所受到的应力状态和热状态的不同，就是小区各种构造活动产生的根源，最后从区内地质构造形成过程讨论了区内地壳不同结构形成的演化历史。     

三维旋转式自动进样器的研制

介绍了自行研制的三维旋转式自动进样器的结构和特点，提出了三维模式、气动升降臂、旋转定位的自动进样器解决方案，并成功地用于自动进样器的研制。文章中给出了三维旋转式自动进样器的组成，气动式升降臂控制原理和系统的软件流程。     

晚太古代Sanukite（赞岐岩）与地球早期演化

Shirey and Hanson(1984)将某些太古代的高镁闪长岩套称为sanukite(赞岐岩),类似于日本中新世(11～15Ma)Setouchi火山岩带的高镁安山岩。Sanukitoids由闪长岩-二长闪长岩-花岗闪长岩组成,不同于TTC岩套(奥长花岗岩-英云闪长岩-花岗闪长岩)。Sanukitoids具有下列地球化学特征:富Mg,Mg~#>0.60,Ni和Cr>100μg/g,Sr和Ba>500μg/g,LREE富集(大于球粒陨石100倍),无Eu异常。高镁安山岩在太古代很少见,而其相应的侵入岩高镁闪长岩或sanukitoids,虽然数量也很少,但却是各地晚太古代地体中随处可见的。Sanukitoids的原始岩浆是交代的地幔楔部分熔融形成的,随后可能经历了广泛的分离结晶作用。TTC和sanukitoids岩套可以相伴产出,二者均与板片熔融有关,TTG与其直接有关,sanukitoids可能与其间接有关。全球Sanukitoids主要集中在晚太古代时期,可能暗示板块的消减作用在～3.0Ga以后才起了重要的作用。