基于贝叶斯原理的爆炸识别判据综合技术研究

基于贝叶斯原理,建立了地震事件识别判据的综合方法（简称贝叶斯方法）, 并针对中亚地区大量地震事件,采用该方法综合了不同台站和不同频带的P/S震相幅值比判据. 该方法的主要优点是能够给出事件属于爆炸的概率,而且充分考虑了判据之间的相关性. 理论计算和模拟数据分析结果表明, 贝叶斯方法是最优的综合方法, 其识别效果比任何单个判据好,也好于普通线性组合方法的识别效果. 针对中亚地区大量地震事件综合不同台站和不同频带的P/S震相幅值比判据的结果也表明,贝叶斯方法的误识率低于单个判据和线性组合方法的误识率.      

利用小波包变换时频谱识别宁夏及邻区的地震和爆破

采用dmey小波基函数分别对地震和爆破事件的垂直向记录信号进行小波包变换,计算各事件信号的归一化时频谱值以及P波和S波时频谱值达到最大时的频率fmp和fms,比较地震信号和爆破信号P波段(0～6.25Hz)和S波段(0～6.25Hz)在各相同分解频带内的瞬时谱最大值差异,寻找合适的单项定量识别指标,并综合各单项识别指标形成综合识别判据。运用综合识别判据对银川台记录到的宁夏及邻区14个地震事件和19个爆破事件进行判别,结果表明,各单项定量识别指标的识别率均在80%以上,综合判别结果均与事件的真实类型一致。     

P/S震相幅值比判据对低震级地震事件的适用性检验c

基于中国新疆及中亚地区大量天然地震和地下爆炸，检验了较大震级情况下得到的区域P/S震相幅值比识别判据对低震级地震事件的适用性. 分析结果表明，对较大震级地震事件具有较好识别效果的P/S震相幅值比判据对低震级事件同样适用，而且对低震级事件也具有与较大震级事件大致相当的识别效果. 据WMQ、BLK、MUL和MAK台的25个识别效果较好的P/S震相幅值比判据统计， 大于ML3.5和ML3.5以下地震事件的误识率之差约为2个百分点.      

安徽及周边地区小爆破的识别与判据研究

根据安徽测震台网记录的爆破与地震的数字资料,采用波谱分析方法,对该区域记录的小爆破与小震级地震事件计算纵横波拐角频率和卓越周期,试图获得爆破和地震识别的定量指标。对比研究波谱特征,发现爆破与地震的纵横波拐角频率和卓越周期等存在明显差异,为该地区小爆破的识别,提供了新的判据。最后,对爆破与地震其他方面的判据特征进行了总结。     

用决策方法识别地震和爆破

在矩阵决策方法的基础上,建立了识别地震与爆破的矩阵决策算法（MDA）．着眼于快速识别,研究了5个判据. 其中初动方向和振幅比判据的效果较好．用MDA算法对北京附近62个事件进行了识别和检验得到:用5个判据C检验的正确识别率达到97%, U检验也达到93%,识别效果较好;依次从5个判据中任选4个判据作决策识别和检验, 10个结果中有7个的正确识别率在93.3%以上.结果表明,本文建立的MDA算法和所选的特征能有效地识别地震与爆破,可应用于两者的快速识别．      

孕震条带识别的重整化群方法

在前人研究的基础上,引入重整化群方法进行孕震条带的识别．从理论上给出了识别孕震条带的定量判据,并对文献［１］中的３２个地震活动条带进行了回顾性的预报检验．结果表明,这３２个地震活动条带中有２９个为孕震条带,其余３个则为非孕震条带．同时将重整化群方法和文献［１］中方法所得的判据指标进行了比较,结果表明,重整化群方法除了具有明显的物理意义之外,在识别孕震条带的判据上更趋于严格,更符合地震活动条带的客观分布     

琼北确定性人工爆破与天然地震识别判据

对琼北地区确定性井下人工爆破和天然地震事件波形特征进行梳理,分析人工爆破与天然地震波不同判据特征。结果表明:P波初动方向、振幅比是识别人工爆破和天然地震的2个主要判据;尾波持续时间、S波最大振幅与持续时间比可作为识别人工爆破和天然地震的一般判据;发震时间可根据事件的强度、规律性,并结合其他判据,仅作为识别过程中的参考因素。     

平顶山地区爆破识别判据分析

对2008年1月1日-2012年12月31日河南数字地震台网记录的平顶山地区的地震与爆破事件,从初动方向、振幅比、周期比和记录波形对比等进行分析,结果表明：振幅比和记录波形对比可以作为平顶山地区爆破识别判据,初动方向可以作为该地区爆破识别的辅助判据.     

武汉遥测台网地震记录中小爆破的判据研究

主要研究武汉地区小当量爆破(即矿山爆破)事件与小震级(ML 2.0左右)地震事件的识别与判据.     

周期-频度谱在小爆破自动识别研究中的应用

历年来在所开展小爆破识别与判据研究的基础上,进行了计算机易于实现爆炸事件自动识别判据的研究,通过对近震、爆破、矿塌和远震事件的周期-频度谱、波形不规则指数、卓越周期开展的研究,确定了切实可行的爆破事件自动识别方法和判据,达到了77%以上的正确自动识别概率。关键词爆破;自动识别;周期-频度谱;波形不规则指数;卓越周期     

Application of Fisher method to discriminating earthquakes and explosions using criterion m_b/M_S

Introduction Earthquake magnitude is a measurement of earthquake intensity, which is one of the basic seismic parameters. The body-wave magnitude mb and surface-wave magnitude MS are based re- spectively on different wave spectrum amplitudes, therefore, the magnitude used as a criterion has its sound physical basis, which is in fact to distinguish the frequency components of seismic waves excited by explosion and earthquake. The magnitude criterion has a very clear physical meaning. Proposed …     

Application of Fisher method to discriminating earthquakes and explosions using criterion <Emphasis Type="Italic">m</Emphasis><Subscript>b</Subscript>/<Emphasis Type="Italic">M</Emphasis><Subscript>S</Subscript>

We try to give a quantitative and global discrimination function by studying m _b/M _S data using Fisher method that is a kind of pattern recognition methods. The reliability of the function is also analyzed. The results show that this criterion works well and has a global feature, which can be used as first-level filtering criterions in event identification. The quantitative and linear discrimination function makes it possible to identify events automatically and achieve the goal to react the events quickly and effectively.     

Application of Fisher method to discriminating earthquakes and explosions using criterion m b/ M S

We try to give a quantitative and global discrimination function by studying m _b/M _S data using Fisher method that is a kind of pattern recognition methods. The reliability of the function is also analyzed. The results show that this criterion works well and has a global feature, which can be used as first-level filtering criterions in event identification. The quantitative and linear discrimination function makes it possible to identify events automatically and achieve the goal to react the events quickly and effectively. Contribution No.05FE3018, Institute of Geophysics, China Earthquake Administrtion.     

一种适用于黄土斜坡地震稳定性快速评估的综合判别方法——以宁夏西吉县为例

选取宁夏西吉县为目标区,对区内1920年海原8.5级特大地震所诱发的347处黄土地震滑坡进行野外调查,获取了详实的基础数据.在此基础上结合遥感影像解译,总结了研究区内黄土地震滑坡的分布特征,并依此提出了宏观、定性的黄土斜坡地震稳定性快速判别方法.基于分布特征选取了坡高、坡角、坡向及地震动强度作为基本参数,应用MLP神经...     

基于马尔科夫随机场的岩性识别方法

通过地震反演数据识别岩性,是地震反演的一项基本任务.由于不同岩性的弹性参数范围常常存在一定程度的重叠,所以给岩性识别带来了很大的困难.本文以叠前反演的弹性参数为基础,通过马尔科夫随机场(Markov Random Field简写为MRF)建立先验模型,按照解释好的测井资料,对不同岩性的弹性参数进行统计,得到计算所需的参数,在贝叶斯(Bayesian)框架下建立岩性分类的目标函数,达到岩性识别的目的.通过马尔科夫随机场建立先验模型,能够建立相邻点间的相互作用关系,得到横向上延续的岩性剖面.本文使用一个楔形模型和Marmousi Ⅱ模型对该方法进行了测试,结果表明,该方法有效可行.同时,本文通过加入误差的方法,检验了反演存在误差对识别结果的影响.     

基于矩特征和局部特征的高原子序数液体容器识别

目前液体检查是地铁、机场安检工作中极为迫切的需求。本文提出了一种全新的基于全局和局部特征的高原子序数液体容器识别方法。该方法基于全局区域提取其组合矩特征,在识别初期首先迅速找到与模型库中相似的物品和差异较小的姿态,然后根据局部特征即容器壁投影特征和瓶底特征进行判断和提高识别精度。实验结果证明,该方法很好地结合了目标的整体和局部信息,能够解决容器在与高原子序数物品局部遮挡问题,同时具有较高的识别精度。     

地震事件自动识别技术及其在南岭流动台阵的应用?

地震事件识别是地震层析成像的重要组成部分。然而,在处理宽频带流动台阵天然地震记录中识别地震事件过程中,利用传统的人工识别方法耗时巨大,效率十分低。本文首先运用STA/LTA 对地震事件进行初步判断,并结合支持向量机信号检测算法和多台联合检验法来提高地震事件判别的准确度及抗干扰能力,达到天然地震事件的自动识别。南岭流动台阵数据的应用结果表明该综合识别算法可自动快速准确地判别地震事件,并可用于地震震相的拾取。     

Application of the Wavelet Packet Method in Discrimination Between Nuclear Explosion and Earthquake

Although the CTBT (Comprehensive Nuclear Test-Ban Treaty) was passed in 1996, it is still necessary to develop new and highly efficient methods (Wu Zhongliang, Chen Yuntai, et al.,1993 ; Xu Shaoxie, et al. 1994; Richard L. Garwin, 1994) to monitor possible events. Many discrimination criteria (Xu Shaoxie, et al., 1994 ; Institute of Geophysics, Chinese Academy of Sciences, 1976; Richard L. Garwin, 1994) have been put forward since the 1950s. The results show that each of the existing criteria has its own limitation, but the seismological method is an important and efficient method in the discrimination between nuclear explosion and earthquake. Especially in recent years, because of the little and little equivalent as well as the increasing hiding steps used in the test, a number of more efficient seismological methods have been worked out. In this paper, a new discrimination method, the Wavelet Packet Component Ratio (WPCR) method, is put forward. This method makes full use of the difference in variation with time between the spectra of nuclear explosions and earthquakes. Its discrimination efficiency is rather high.     

Migration velocity analysis using a genetic algorithm

Migration velocity analysis, a method for determining long wavelength velocity structure, is a critical step in prestack imaging. Solution of this inverse problem is made difficult by a multimodal objective function; a parameter space often vast in extent; and an evaluation procedure for candidate solutions, involving the calculation of depth-migrated image gathers, that can be prohibitively expensive. Recognizing the global nature of the problem, we employ a genetic algorithm (GA) in the search for the optimum velocity model. In order to describe a model efficiently, regions of smooth variation are identified and sparsely parametrized. Region boundaries are obtained via map migration of events picked on the zero-offset time section. Within a region, which may contain several reflectors, separate components describe long and short wavelength variations, eliminating from the parameter space, models with large velocity fluctuations. Vital to the success of the method is rapid model evaluation, achieved by generating image gathers only in the neighbourhood of specific reflectors. Probability of a model, which we seek to maximize, is derived from the flatness of imaged events. Except for an initial interpretation of the zero-offset time section, our method is automatic in that it requires no picking of residual moveout on migrated gathers. Using an example data set from the North Sea, we show that it is feasible to solve for all velocity parameters in the model simultaneously: the method is global in this respect also.     

The solution of the one-dimensional inverse problem for induction soundings by an efficient linearization technique

A non-parametric method, the efficient linearization technique (ELT), is proposed for the inversion of induction soundings for a spherical Earth model with a radial conductivity distribution. The method is based on the fact that when linearizing the operator of the direct problem, the quantitative estimate of its non-linear term is taken into account, which makes the solution search procedure stable. At each iteration stage, the conductivity function correction is sought in the region where linearization is admissible. ELT makes it possible to evaluate the resolving power of the data and also the confidence interval for the conductivity function. Model examples illustrate the features of this method. The results of interpretation of magnetotelluric data are compared with nearby drill hole resistivity logs. A model of the conductivity distribution in the mantle based on global magnetovariational data available up to 1986, is constructed. This model is consistent with modern knowledge of physical processes occurring in the interior of the Earth.