共查询到19条相似文献，搜索用时 140 毫秒
1.
地震台阵的概念产生于1960年代.最初的目的是检测和识别地下核爆炸.随着时间的推移,台阵资料的应用范围逐渐扩大.如:地震台阵在地球表面稠密的空间采样使台阵资料能够应用于地球内部速度结构细节的研究、区域尺度的高分辨率层析成像、小尺度地幔结构研究以及核幔边界与内核的各向异性研究. 相似文献
2.
中国的地震台阵建设与发展比国外晚了几十年.目前国内地震台阵正在不断地建设,而缺少的就是台阵技术,如能够把已有的台阵技术应用到我国的台阵中,就可以让台阵发挥它们应有的价值.作者根据国外的参考文献主要讨论了台阵地震学的主要技术方法并把这些方法应用到中国的IMS台阵,并给出了应用实例.结果表明,地震台阵使我们对地下结构的研究更加精细,使我们对微弱信号的识别更加轻松.如果我国现有台阵都能应用台阵地震学技术将对我国地震学和地球物理学的发展起到很大的推动作用. 相似文献
3.
4.
地震台阵的历史起始于 50年代未 ,当时其目标主要是检测、区别核爆炸信号和地震信号 .地震台阵研究包括地震台阵技术研究和地球物理学中应用研究 .其中台阵技术研究可以分为台阵建设和数据处理方法研究两大部分 (Anne,1 990 ) ,地震台阵理论研究的发展可涉及到地球物理学领域的许多科学问题(Tormod,1 989;Mykkeltveit,Bungum,1 984) .台阵主要用于监测微弱事件 ,而台阵的响应特性是衡量台阵对微弱事件监测能力的一个很重要标志 ,因此 ,不论是考察一个台阵 ,还是要着手建立一个台阵 ,必做的内容之一就是计算台阵的响应特性(Harjes,1 990 ) … 相似文献
5.
6.
7.
地球深部结构探测是地球物理学的核心领域,而地震体波可以深入地球内部且分辨率较高,是研究地球内部结构不可或缺的技术手段。基于背景噪声提取高信噪比体波信号技术的迅速发展,极大地促进了地震学的发展和应用范围,使其在地球深部结构成像、城市浅层空间探测等领域日益发挥出重要作用。本文详细综述了如何利用地震干涉法及台阵处理技术提取出用于研究不同探测尺度（局部、区域、全球）的各类体波信号。其中,地震干涉法通过对地震台站记录到的波形信号进行互相关,抵消掉重合的射线路径,最后得到台站对之间的地震记录;而台阵处理方法是基于接收器台阵发展起来的数据处理手段,该技术不仅能够进一步提高信噪比（SNR）,而且能够获得方位信息。一般来讲,背景噪声中包含的体波信号能量远低于面波信号能量,提取难度大。本文着重介绍了Bin-叠加法、双波束方法（DBF）以及相位加权叠加法（PWS）,并对3种方法的适用条件进行了总结。 相似文献
8.
根据各大网站地震目录和前人研究成果,分析全球地震台网与地震台阵、我国区域台网与地震台阵的监测能力,阐述了地震台阵与密集台网/台阵的区别。研究表明,对同一地区所检测的地震数,地震台阵是地震台网的3-10倍,而震级下限可降低1.2-2级。一般情况下,以微弱信号检测为目的的地震台阵监测能力均优于以结构研究为目的的密集台网/台阵,2种台阵是目的、性质、孔径、形状、台间距、技术手段、研究方法均不同的监测系统。 相似文献
9.
地震台阵的历史起始于５０年代末,当时其目标主要是检测核爆炸产生的地振动信号与鉴别爆炸信号和地震信号,我国地震学家在７０年代也曾对台阵作初步研究,在台阵的寻展过程中,许多新技术被引起用于信号处理,数据分析和解释,本文主要介绍频率扫描聚束及视速度扫描聚束在台阵数据处理的应用,并使用该技术在上海地震台阵选址中的具体实现。 相似文献
10.
在哈萨克斯坦的5个现代化数字地震台阵中,4个小孔径同心圆结构的IMS简约型台阵建设、维护方便,全方位监测能力强,1个十字型结构中等孔径台阵,因对特定方位敏感,对更远距离已知核试验点监测能力更强。台阵观测场地均处于完整稳定的构造块体,内部岩石迁移性良好,噪声水平低,保证了对远处微弱地震信号的监测及各子台信号的相似性。地震检波器良好的性能,保证了台阵的地震信号记录质量和数据研究基础。采用卫星传输方式,有效保证了数据的实时性。哈萨克斯坦的地震台阵,其选址、布局、仪器、数据传输等台阵建设,为中国地震台阵发展建设提供了经验借鉴。 相似文献
11.
Improving Seismic Resolution Through Array Processing Techniques 总被引：4，自引：0，他引：4
Seismic arrays, first introduced in the late 1950s to detect underground nuclear explosions, have helped to improve our knowledge about the structure of the Earth for the last 40 years. During these years, numerous array processing methods have been developed that use the high signal coherence and accurate timing of array data to generate high-resolution images of Earth structure. Here, we present an overview of resolution issues related to seismic array studies of Earth structure by first introducing basic array processing techniques and then discussing more advanced techniques applied to array data recently. The increase of seismic stations deployed in experiments or permanently in many regions of the globe allows a much denser sampling of the seismic wavefield. This dense sampling enables the adaptation of controlled source analysis techniques for the study of Earth structure using earthquakes with higher resolution than previously possible. Here we will discuss different migration methods of teleseismic data that use the incidence angle information of scattered arrivals to obtain images of Earth structure. Finally, we show data examples how these methods can be used to increase our knowledge of the structure of the Earth’s deep interior. 相似文献
12.
在构建现代地球模型时,地球内部分层结构主要是根据地震波资料确定的;而地球内部密度及弹性参数,特别是地幔以下大尺度结构的密度分布,则主要是根据地球自由振荡的弹性简正模观测资料确定的.本文概述了地球自由振荡简正模本征值的求解理论和方法,介绍了球型和环型模态位移场表达式,讨论了地球自由振荡模态的衰减、分裂与耦合效应;总结了多线态分裂谱线探测和分裂参数估计的方法,综述了利用弹性简正模开展地震矩张量、地球三维非均匀性结构和内核超速旋转约束与反演研究的主要进展和存在的问题.最后作为展望,本文还讨论了地球自由振荡简正模的未来研究趋势. 相似文献
13.
利用甘肃地震台网记录的sP前驱波研究 汤加—斐济俯冲带“410”间断面深度 总被引：2，自引：0，他引：2
本文首先利用甘肃数字测震台网和甘东南野外观测流动台阵记录的汤加—斐济俯冲带深震震相sP, 使用倾斜叠加方法有效提取sP在近源区“410”速度间断面底界面反射的弱前驱波s410P; 其次基于CRUST1.0修正的IASP91模型, 通过震相sP与其前驱波s410P的到时差对比, 给出了汤加—斐济俯冲带“410”速度间断面底部反射点的深度约为398.5 km, 抬升约11.5 km, 这与俯冲带与近源区“410”间断面的相互作用有关; 最后得到了该区域新的地震波速度模型IASP91_Tonga. 本文结果将对更好地认识该俯冲带的复杂结构、 正确理解地球深部的动力学过程具有重要的参考价值. 相似文献
14.
Based on the data synthesis simulation and the actual processing of the airgun seismic source signal, three quantitative indicators of signal-to-noise ratio, waveform correlation coefficient and phase offset, are superimposed. We systematically evaluate the functions of the following three stack methods including linearity, phase weighting and S-transform in the extraction of weak signals under strong background noise and quantitatively estimate the reliability of the stack results. Through the comprehensive discussion of the above three methods of stack results, the preliminary comparative analysis believes that the linear stack signal-to-noise ratio is low, but the waveform distortion is minimal; the phase-weighted superimposed signal-to-noise ratio is high and the phase offset is small, but the results of the waveform quality and linear stack are larger than the deviation; the S-transform stack has a relatively higher signal-to-noise ratio and a small loss of waveform amplitude, but there is a certain phase shift phenomenon. It is therefore suggested that linear stack technology should be used when the requirements of both waveform quality and time precision are high. However, the selection of the stack method when the airgun source excitation is limited should be emphasized. If high fidelity is required, the S-transform stack method should be selected; if the required time is high, accuracy can be selected by phase-weighted stack method to achieve reasonable extraction of weak signals. 相似文献
15.
Amir Khan 《Surveys in Geophysics》2016,37(1):149-189
Determining Earth’s structure is a fundamental goal of Earth science, and geophysical methods play a prominent role in investigating Earth’s interior. Geochemical, cosmochemical, and petrological analyses of terrestrial samples and meteoritic material provide equally important insights. Complementary information comes from high-pressure mineral physics and chemistry, i.e., use of sophisticated experimental techniques and numerical methods that are capable of attaining or simulating physical properties at very high pressures and temperatures, thereby allowing recovered samples from Earth’s crust and mantle to be analyzed in the laboratory or simulated computationally at the conditions that prevail in Earth’s mantle and core. This is particularly important given that the vast bulk of Earth’s interior is geochemically unsampled. This paper describes a quantitative approach that combines data and results from mineral physics, petrological analyses of mantle minerals, and geophysical inverse calculations, in order to map geophysical data directly for mantle composition (major element chemistry and water content) and thermal state. We illustrate the methodology by inverting a set of long-period electromagnetic response functions beneath six geomagnetic stations that cover a range of geological settings for major element chemistry, water content, and thermal state of the mantle. The results indicate that interior structure and constitution of the mantle can be well-retrieved given a specific set of measurements describing (1) the conductivity of mantle minerals, (2) the partitioning behavior of water between major upper mantle and transition-zone minerals, and (3) the ability of nominally anhydrous minerals to store water in their crystal structures. Specifically, upper mantle water contents determined here bracket the ranges obtained from analyses of natural samples, whereas transition-zone water concentration is an order-of-magnitude greater than that of the upper mantle and appears to vary laterally underneath the investigated locations. 相似文献
16.
对稀疏/非规则采样或者低信噪比数据,射线束提取困难并伴随有假频产生,对叠加剖面和道集造成严重干扰.为了提升射线束偏移在稀疏和低信噪比地震数据采集中的成像效果,本文提出基于三角滤波的局部倾斜叠加波束形成偏移假频压制方法.射线束偏移首先将地震数据划分为超道集,经过部分NMO后转化为以射线束中心定义的共偏移距数据,倾斜叠加和反假频操作均在局部共中心点坐标上实现.时间域倾斜叠加是对地震数据的时移累加操作,三角低通滤波同样可以在时间域完成,在对地震数据进行因果和反因果积分后,亦为地震数据的时移累加.因此,三角低通滤波与倾斜叠加可在时间域结合同时完成,避免了频域滤波的正反傅里叶变换.本文在反假频公式中加入权重系数,用以对反假频的程度进行控制,达到分辨率和噪声压制的最佳折衷.以某海上三维实际数据为例,文中展示了反假频射线束形成对偏移叠加剖面和共成像点偏移距道集中的噪声进行了有效压制. 相似文献
17.
Giant earthquakes generate rich signals that can be used to explore the characteristics of the hierarchical structure of the Earth’s interior associated with the eigenfrequencies of the Earth.We employ the spectral element method,incorporated with large-scale parallel computing technology,to investigate the characteristics of global seismic wave propagation excited by the2011 Mw9.0 Tohoku earthquake.The transversely isotropic PREM model is employed as a prototype of our numerical global Earth model.Topographic data and the effect of the oceans are taken into consideration.Wave propagation processes are simulated by solving three-dimensional elastic wave governing equations with the seismic moment tensor obtained from the Global Centroid Moment Tensor Catalog.Three-dimensional visualization of our computing results displays the nature of the global seismic wave propagation.Comparative analysis of our calculations with observations obtained from the Incorporated Research Institutions for Seismology demonstrates the reliability and feasibility of our numerical results.We compare synthetic seismograms with incorporated and unincorporated ocean models.First results show that the oceans have obvious effects on the characteristics of seismic wave propagation.The peak displacement and peak velocity of P waves become relatively small under the effect of the ocean.However,the effect of the ocean on S-waves is complex.The displacement and velocity of S waves decrease rapidly over time using an unincorporated ocean model.Therefore,the effects of the ocean should be incorporated when undertaking quantitative earthquake hazard assessments on coastal areas.In addition,we undertake comparative analysis on the characteristics of the Earth’s oscillation excited by the 2004 Sumatra-Andaman,2008 Wenchuan,and 2011Tohoku earthquakes that incorporate the effect of the Earth’s gravitational potential.A comparison of the amplitude spectra of the numerical records indicates that energy released by the three big earthquakes is different.Our comparative analysis realizes that the computing results can accurately reproduce some eigenfrequencies of the Earth,such as toroidal modes 0T2 to 0T13and spheroidal modes 0S7 to 0S31.These results demonstrate that numerical simulations can be successfully used to investigate the Earth’s oscillations.We propose that numerical simulations can be used as one of the major tools to further reveal how the Earth’s lateral heterogeneities affect the Earth’s oscillations. 相似文献
18.
本文评述了过去60年内固体地球内部几何结构和物性结构成像的进展，包括地震学研究的进展；重磁位场研究的进展；电磁学研究的进展.文章还指出了他们进一步发展的某些方面. 相似文献
19.
Understanding the processes that occur in the transition from the Pacific Ocean to Eurasia is key to constructing the tectonic models of the Earth’s shells and the convection models of the upper mantle. The electromagnetic methods permit estimating the temperature and fluid content (and/or carbon (graphite) content) in the Earth’s interior. These estimates are independent of the traditionally used estimates based on seismic methods because the dependence of electrical conductivity on the physical properties of the rock is based on different principles than the behavior of the elastic waves. The region is characterized by a complicated geological structure with intense three-dimensional (3D) surface heterogeneities, which significantly aggravate the retrieval of the information about the deep horizons in the structure of the Earth’s mantle from the observed electromagnetic (EM) fields. The detailed analysis of the nature of the deep electrical conductivity and structural features of the transition from the Pacific to Eurasia included numerical modeling of the typical two- and three-dimensional models has been carried out. Based on this analysis, the approaches that increase the reliability of the interpretation of the results of the EM studies are suggested. 相似文献