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地震磁扰动分析方法研究进展 总被引：1，自引：0，他引：1
地震孕育及发生过程中伴随着不同程度的电磁信号,有效的分析方法不仅能成功提取显著异常信号,而且能加深对震磁异常机理的理解.本文从地震电磁扰动机理出发,介绍了动电效应和微破裂机制两种最可能的震磁异常产生机理.此外,从方法原理、震例、重要进展三个方面重点介绍了极化法、主成分分析法、分形分析法和梯度定向法四种异常提取能力较强的分析方法在震磁关系研究中的应用,对各种方法的典型震例进行了总结,并对其展开了相关评述和应用展望.对地震地磁扰动研究具有一定的参考意义. 相似文献
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文中计算了由日、月引潮力在地球内产生的潮汐应力场,研究了潮汐应力对地震的触发作用.采用的地球模型是分为十五层的球对称模型.对于近30年来我国或我国邻近发生的七十次较大的地震,计算了震源处在发震时刻的球坐标系中的潮汐应力.通过坐标变换,得到了发震断层面中的正应力及沿错动矢量方向的剪应力.根据岩石的库仑剪破裂准则来判断潮汐应力对所研究的震例是否具有触发作用.结果表明,在七十个震例中,潮汐应力对其中四十三个有触发作用.对于华北地区的十八个震例,潮汐应力对其中十四个有触发作用.还可看出,对于浅源走滑型地震有较明显的触发作用,而对浅源斜滑及倾滑型地震则没有明显的触发作用.对国外七十二个震例的计算结果得到了类似的结论.最后,对华北地区中任一可能的发震地点,提出一种根据潮汐应力来预测发震的危险时间范围的方法. 相似文献
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本文收集了国外地震预测预报研究中一些引起关注的震例,包括回溯性前兆检验的震例和实际预测预报的震例,作为一个不完整的索引,以期对国内相关领域的研究有所帮助。 相似文献
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介绍了矿山地震与瓦斯突出等煤矿灾害及成因， 并通过若干煤矿瓦斯突出和矿山地震的同震现象，论述了这些灾害在动力过程中的内在关系.这些震例表明，在高瓦斯煤矿， 矿山地震与瓦斯突出存在密切的相关.认为较大矿震伴随瓦斯的低值延时响应可能是瓦斯突出的预警信号.从矿震定位、震源机制、矿震成因、瓦斯突出条件等分析了矿震与瓦斯突出相关的机理. 进一步介绍了瓦斯流体对矿震的触发作用，尤其超临界流体的特殊性质在矿震发生中的重要作用.依据矿震与构造地震在机制方面的相似性， 讨论了上述结果在震源物理研究中的意义. 相似文献
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探讨了多标度分形在刻划复杂系统方面的优越性,研究了江苏及邻区1970年以来的5.5级以上地震的多标度分形特征,着重研究了地震前后多标度分形的广义维数谱和奇异性谱.研究结果表明:所有震例的广义维数谱和奇异性谱均经历了远离地震时、异常出现时和异常消失时的三个特征变化阶段;异常出现的时间在震前半年至一年半内;多数震例异常在震前几个月内回返恢复,少数在震后数个月内恢复.上述结果说明利用地震时序的多标度分形特征对于该地区的半年至一年尺度的中强地震预报是有意义的. 相似文献
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在东海潜在震源区冲绳海槽假定了五个震源点,根据Steven地震海啸地震参数经验值作为初始条件,分别考虑6.5、7.0、7.5、8.0、8.5、9.0级地震条件下的30个震例,采用数值模拟的方法,对海啸在东海传播过程进行情境分析,特别是对上海沿岸地区可能会遭受的海啸灾害做了较为精细的研究.结果发现:小于8.0级的震例对上海地区几乎不会造成影响;8.0级震例只有最北端震源点震例会对上海地区有明显影响;8.5级以及9.0级震级基本上均会对上海沿岸地区造成较大的影响.特别是冲绳海槽北段9.0级震例可能会对上海沿岸局部地区造成危害,最大波高可达3.9m. 相似文献
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采用极化分析方法处理地磁秒数据.对不同台站地磁秒数据进行分析发现,极化值在地震发生前约2个月内有明显异常,且在傅里叶频谱上表现不太明显.另外,不同地磁分量的极化值映震效果不同,大部分震例极化值升高、振幅增大,小部分震例极化值低值、平稳.研究认为,该方法可以用于地磁秒数据震磁异常信息提取. 相似文献
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我国地震电磁卫星数据分析及应用研究进展 总被引：1，自引：0，他引：1
本文介绍了地震电磁卫星数据分析在中国地震电磁学方面的研究进展情况,其中包括卫星数据分析的整体思路的确定,以及具体在电离层正常背景分析,干扰因素影响,数据分析方法和震例研究结果.目前的应用研究表明,电离层各观测参量具有不同的季节性及区域性复杂的正常变化背景,对提取地震异常增加了很多困难.而震例研究反映震前确实存在一定程度的电离层异常,空间电磁异常信息具有短临性和区域性特征,但异常的重复性、空间分布的相似性检验及背景场理论模拟等方法还需要在今后的工作逐步加强. 相似文献
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This paper investigates in detail the nature of diffraction of plane P waves around a canyon in poroelastic half-space, and studies the effects of incident frequency, drainage condition, porosity, etc, on the diffraction of waves. It is shown that the surface displacement amplitudes of the drained case are close to those of the undrained case, however, the surface displacement amplitudes of the dry case are very different from those of the saturated (either drained or undrained) cases. There are large phase... 相似文献
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The Next-Generation Liquefaction (NGL) project was launched to (1) substantially improve the quality, transparency, and accessibility of case history data related to ground failure; (2) provide a coordinated framework for supporting studies to augment case history data for conditions important for applications but poorly represented in empirical databases; and (3) provide an open, collaborative process for model development in which developer teams have access to common resources and share ideas and results during model development. Work to date has focused on compiling high-value case histories, developing a database template, and planning for needed supporting studies. We describe the project motivation, explain and illustrate how data resources will be compiled and organized, summarize preliminary results from ongoing data collection, describe needed supporting studies, and review project status and next steps. 相似文献
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The interaction between landscape and stream processes has been well documented, and thus it is plausible to assume that landscape factors in a given watershed have a determinant function in stream network initiation and formation. Although past research has identified certain general relationships between stream drainage density and other environmental factors, no definite model for stream delineation has yet emerged. Particularly at smaller scales, drainage network extraction approaches have been devised that are generally independent of often widely heterogeneous landscape conditions. Utilizing digital terrain models alone for this purpose is, in many cases, problematic and inaccurate. This research effort involved using an artificial neural network (ANN) for the exploration of a number of environmental factors and information extracted from satellite images (Landsat 7 ETM+) with regard to finding the most indicative factors for drainage network location. The environmental variables included a series of available topographic, soil and lithology factors. Two hydrologically and geographically diverse case studies, one in Pennsylvania and the other in southern Italy, were used to this end. The results show that various spectral band ratios (1/4, 2/4 and 3/4) were mutually identified as significant in both case studies. Additionally, both case studies illustrated that different factors belonging to general parameter groups (soil and topography parameters) were identified by the ANN for each case, suggesting that future drainage network derivation methodologies should possibly consider that certain groups of environmental factors are more important for certain geographic regions than for others. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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This study examines the performance of integration methods for hybrid simulation of large and complex structural systems in the context of structural collapse due to seismic excitations. The target application is not necessarily for real-time testing, but rather for models that involve large-scale physical sub-structures and highly nonlinear numerical models. Four case studies are presented and discussed. In the first case study, the accuracy of integration schemes including two widely used methods, namely, modified version of the implicit Newmark with fixed-number of iteration (iterative) and the operator-splitting (non-iterative) is examined through pure numerical simulations. The second case study presents the results of 10 hybrid simulations repeated with the two aforementioned integration methods considering various time steps and fixed-number of iterations for the iterative integration method. The physical sub-structure in these tests consists of a single-degree-of-freedom (SDOF) cantilever column with replaceable steel coupons that provides repeatable highlynonlinear behavior including fracture-type strength and stiffness degradations. In case study three, the implicit Newmark with fixed-number of iterations is applied for hybrid simulations of a 1:2 scale steel moment frame that includes a relatively complex nonlinear numerical substructure. Lastly, a more complex numerical substructure is considered by constructing a nonlinear computational model of a moment frame coupled to a hybrid model of a 1:2 scale steel gravity frame. The last two case studies are conducted on the same porotype structure and the selection of time steps and fixed number of iterations are closely examined in pre-test simulations. The generated unbalance forces is used as an index to track the equilibrium error and predict the accuracy and stability of the simulations. 相似文献
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A model for the random vibration of hysteretic and degrading plane frames to Gaussian shot noise or filtered shot noise is presented. The model, which combines the discrete hinge concept previously used in deterministic frame analysis with Bouc's smooth system hysteresis, results in a non-linear set of differential equations which can be linearized in closed form without recourse to the Krylov-Bogoliubov assumptions. Solution is iterative in the stationary case and by numerical integration with stepwise updates in the non-stationary case. Numerical studies are presented of strong girder and strong column two storey, one bay frames. These studies indicate that the model can locate the sites of yielding and provide reasonable values of structural response as compared with simulation data. Moreover, the model can provide a joint by joint breakdown of the structure energy dissipation rate. 相似文献
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电磁波增长、等离子体密度、粒子通量的扰动与地震的关系已经被前人研究了二十年了。尽管不断有人提出新的震例分析试图说明它们之间存在关联,但是只有通过对大量数据进行详尽的统计分析才能得到令人信服的结论,才有可能将卫星数据用于地震预报。本文前一部分回顾了这些年比较有代表性的关于空间卫星观测电磁波与地震关系的统计分析文献,后一部分回顾了地震上空等离子体密度、粒子通量扰动与地震关系的文献。 相似文献
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Tymon Zieliński Tomasz Petelski Przemysław Makuch Agata Strzałkowska Agnieszka Ponczkowska Krzysztof M. Markowicz Georgius Chourdakis George Georgoussis Susanne Kratzer 《Acta Geophysica》2012,60(5):1359-1385
This paper presents the results of the studies of aerosol optical properties measured using lidars and sun photometers. We describe two case studies of the combined measurements made in two coastal zones in Crete in 2006 and in Rozewie on the Baltic Sea in 2009. The combination of lidar and sun photometer measurements provides comprehensive information on both the total aerosol optical thickness in the entire atmosphere as well as the vertical structure of aerosol optical properties. Combination of such information with air mass back-trajectories and data collected at stations located on the route of air masses provides complete picture of the aerosol variations in the study area both vertically and horizontally. We show that such combined studies are especially important in the coastal areas where depending on air mass advection directions and altitudes the influence of fine or coarse mode (in this case possibly sea-salt) particles on the vertical structure of aerosol optical properties is an important issue to consider. 相似文献
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A network of knowledge on applying an indicator‐based methodology for minimizing flood vulnerability
Flood vulnerability assessment plays a key role in the area of risk management. Therefore, techniques that make this assessment more straightforward and at the same time improve the results are important. In this briefing, we present an automated calculation of a flood vulnerability index implemented through a web management interface (PHP) that enhances the ability of decision makers to strategically guide investment. To test the applicability of this methodology using this website, many case studies are required in order to cover the full range of cases in terms of scale such as river basin, subcatchment and urban area. This requires prompt solutions with large amounts of data and this has led to the development of this automated tool to help organize, monitor, process and compare the data of different case studies. The authors aim to create a network of knowledge between different institutions and universities in which this methodology is used. It is also hoped to encourage collaboration between the members of the network on managing flood vulnerability information and also promoting further studies on flood risk assessment at all scales. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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This paper presents two numerical case studies of medium and strong motion events, namely Loma-Prieta 1989 and Hyogoken-Nambu
(Kobe) 1995. These simulations were performed using CyberQuake model. The cyclic elastoplastic constitutive model is fully detailed in the companion paper. Through these case studies,
we demonstrate the importance of using appropriate constitutive modelling when the part played by nonlinear phenomena is preponderant.
The need to account for 3D kinematics (i.e. the three components of the input motion), is also demonstrated, even though a
1D geometry is considered, as the plastic coupling existing between components of motion during the earthquake, strongly affects
the seismic soil response. 相似文献
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Bruno Meurers 《Journal of Geodynamics》2004,38(3-5):423
Not all of the gravity signals commonly observed in records of superconducting gravimeters have a physically significant meaning. Instrumental noise or signal components generated by specific processing techniques can have a strong effect. This paper analyzes selected case studies from gravity data acquired during the first period of GGP and tries to give an answer to the question of which signals are significant. It is focused on small amplitude variations in the time domain, which are compared with those of conventional spring-type gravimeters. Coherent atmospheric gravity signals due to atmospheric processes associated with strong vertical convection could be observed by different sensors. The second part deals with temporal variations of main tidal parameters, which can be seen clearly in the tidal analysis results from SG data. Synthetic case studies show that they are not strongly influenced by the analysis procedure and therefore mainly reflect ocean loading processes. 相似文献