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新疆及其邻近地区Ｍ≥７强震活动在时间分布上具有明显的有序性。自１７１６年以来的２１次Ｍ≥７强震存在着时间间隔为１１、２５、３０、４１和６０年的有序值。利用强震活动时间的有序性结构，可对该区７级强震进行预测探索。本文同时还应用熵和经验分布函数，讨论了下次强震发生的地点和概率。 相似文献
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基于最大熵原理,得到地震时间间隔和地震震级的概率分布函数。根据时间间隔分布,得到地震发震概率,当概率上升达到警界值时,可对云南5级以上中强地震做出预测。6个月以内中短期预测对应率为91％;3个月以内,短临期预测对应率为73％。根据震级分布,得到用最大熵原理求出的地震理论发生次数,理论发震次数与实际较为接近。用最大熵原理求出了云南不同地区不同震级档次5级以上中强地震的复发周期。分析认为,云南7级以上大震危险性在逐步逼近,西部危险性高于东部。 相似文献
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自从地震复发的“时间可预报模式”（岛崎和中田，１９８０）提出以来，Ｒｅｌｄ（１９１０）的“弹性恢复理论”又引起新的研究热潮。自然界特征地震的复发行为除了有服从确定性时间可预报模式的一面外，还包含受各种随机因素影响而表现的不确定的另一面。因此，如何在时间可预报模式中考虑不确定性，是一个非常值得探索的课题。本研究的目的是探索：当历史地震资料表明一条大型走滑活动断裂带不同段落的地震复发行为总体上服从于时间可预报模式、但明显存在有不确定性时，如何利用可易于获得的资料近似“替代”难以估计的各段落在上一次地震时的位错，进而建立一个概率统计模型对各段落地震平均复发间隔和未来地震复发概率作出估计。作者通过把不确定性引入“时间可预报模式”后，将一次地震ｉ之后至下一次地震ｊ的时间间隔表示成与地震ｉ位错量大小呈正相关随机变量，并称这种带有不确定性的地震原地复发行为为“准时间可预报行为”。对走滑型断裂，一次地震时沿某断裂段的同震平均位错可用该段落地震烈度经验函数代替；假定同一断裂带不同段落具有大体相同的应变积累速率时，复发时间间隔行为可由地震后平静时间的对数与地震烈度的回归方程描述，从而在求地震平均复发间隔时无需单独估计断层的平均 相似文献
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小江断裂带的破裂分段与地震潜势概率估计 总被引：14，自引：0，他引：14
根据历史地震资料分析了云南省东部的小江断裂带强震及大震震源的空间分布,初步划分出7个相对独立的震源段或基本破裂单元.各段历史地震的时间间隔从总体上显示出带有不确定性的时间可预报复发行为.本文初步建立起该断裂带地震时间间隔的统计模型,引入了估算各段以上一次地震大小为背景的平均复发间隔的数学方法,由此估计出该带不同大小地震的给定信度的平均复发间隔区间.进一步提出一种适合于在具有准时间可预报复发为的断裂带上进行地震潜势实时概率分析的方法,并且运用这种方法估算了小江断裂带各段1991年至2005年地震复发的条件概率和概率增益.结果表明:该断裂带的东川以南至嵩明段、澄江至华宁段未来复发强震或大震的可能性较大. 相似文献
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提出了一种以小震的记录作为格林函数来成像中强地震破裂增长的反演方法。该方法通过迭代法中同时拟合多台的Ｐ、Ｓ波形,估计了子事件相对格林函数事件的破裂时间和振幅。我们用小事件作为格林函数反演了发生在帕克菲尔德地区的２次中强地震的加速度图。第１次地震（Ｍ＝４．６）于１９９３年１１月１４日发生在米德尔山,震源深度１１ｋｍ,在下一次帕克菲尔德主震的假定孕震区内。第２次地震（Ｍ＝４．７）于１９９４年１２月２０ 相似文献
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本文应用概率统计方法和灰色系统理论,对华北地区地震危险性作了粗略顶测,给出了华北地区不同预测年限内发生不同强度地震的概率,同时对最近一次强地震发生的时间作了估计。 相似文献
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根据新疆地区本世纪的地震记载，分别取５．５、６．０、６．５、６３／４、７．０、７．２为震级下限，视各组资料为更新过程的样本、分析地震发生的统计特征。经统计检验，不同震级下限的地震发生皆可认为是泊松过程；本世纪初中强地震在记载中可能有遗漏，为避免由此引出的干扰，使用Ｍｓ≥６．５的资料不应早于１９１４年，使用Ｍｓ≥５．５与Ｍｓ≥６．０的资料均应从１９３１年开始；在地震发生大体上为泊松过程的情况下，地震 相似文献
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亚洲大地震的时间有序性与沙罗周期 总被引：6，自引：0，他引：6
根据作者在1997年提出的“信息有序系列”的概念和方法,研究了一些亚洲大地震的时间有序性,本文列举1934-1970年期间亚洲M≥8级大地震,中国历史M≥8级大地震,兴都库什地区中深震（Ms≥7）,结果表明,这些地震的一些时间有序性与反映日食序列变化的沙罗周期关系较密切。亚洲6个8级大地震时间间隔的数值在2130-2210d的范围内,这是地震时间有序性的一个好例子。这表明,时间有序性具有周期性不能描述的特性,它和新兴的复杂性科学有密切联系。 相似文献
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A STUDY REVIEW ON CHARACTERISTICS OF SEISMIC ACTIVITY OF ACTIVE-TECTONIC BLOCK BOUNDARIES IN MAINLAND CHINA 
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下载免费PDF全文 More than 80 percent of strong earthquakes(M≥7.0)occur in active-tectonic block boundaries in mainland China, and 95 percent of strong earthquake disasters also occur in these boundaries. In recent years, all strong earthquakes(M≥7.0)happened in active-tectonic block boundaries. For instance, 8 strong earthquakes(M≥7.0)occurred on the eastern, western, southern and northern boundaries of the Bayan Har block since 1997. In order to carry out the earthquake prediction research better, especially for the long-term earthquake prediction, the active-tectonic block boundaries have gradually become the key research objects of seismo-geology, geophysics, geodesy and other disciplines. This paper reviews the research results related to seismic activities in mainland China, as well as the main existing recognitions and problems as follows: 1)Most studies on seismic activities in active-tectonic block boundaries still remain at the statistical analysis level at present. However, the analysis of their working foundations or actual working conditions can help investigate deeply the seismic activities in the active-tectonic block boundaries; 2)Seismic strain release rates are determined by tectonic movement rates in active-tectonic block boundaries. Analysis of relations between seismic strain release rates and tectonic movement rates in mainland China shows that the tectonic movement rates in active-tectonic block boundaries of the eastern region are relatively slow, and the seismic strain release rates are with the smaller values too; the tectonic movement rates in active-tectonic block boundaries of the western region reveal higher values, and their seismic strain rates are larger than that of the eastern region. Earthquake recurrence periods of all 26 active-tectonic block boundaries are presented, and the reciprocals of recurrence periods represent high and low frequency of seismic activities. The research results point out that the tectonic movement rates and the reciprocals of recurrence periods for most faults in active-tectonic block boundaries exhibit linear relations. But due to the complexities of fault systems in active tectonic block boundaries, several faults obviously deviate from the linear relationship, and the relations between average earthquake recurrence periods and tectonic movement rates show larger uncertainties. The major reason is attributed to the differences existing in the results of the current earthquake recurrence studies. Furthermore, faults in active-tectonic boundaries exhibit complexities in many aspects, including different movement rates among various segments of the same fault and a certain active-tectonic block boundary contains some parallel faults with the same earthquake magnitude level. Consequently, complexities of these fault systems need to be further explored; 3)seismic activity processes in active-tectonic block boundaries present obvious regional characteristics. Active-tectonic block boundaries of the eastern mainland China except the western edge of Ordos block possess clustering features which indicate that due to the relatively low rate of crustal deformation in these areas, a long-time span is needed for fault stress-strain accumulation to show earthquake cluster activities. In addition, active-tectonic block boundaries in specific areas with low fault stress-strain accumulation rates also show seismic clustering properties, such as the clustering characteristics of strong seismic activities in Longmenshan fault zone, where a series of strong earthquakes have occurred successively, including the 2008 M8.0 Wenchuan, the 2013 M7.0 Lushan and the 2017 M7.0 Jiuzhaigou earthquakes. The north central regions of Qinghai-Tibet Plateau, regarded as the second-grade active-tectonic block boundaries, are the concentration areas of large-scale strike-slip faults in mainland China, and most of seismicity sequences show quasi-period features. Besides, most regions around the first-grade active-tectonic block boundary of Qinghai-Tibet Plateau display Poisson seismic processes. On one hand, it is still necessary to investigate the physical mechanisms and dynamics of regional structures, on the other hand, most of the active-tectonic block boundaries can be considered as fault systems. However, seismic activities involved in fault systems have the characteristic of in situ recurrence of strong earthquakes in main fault segments, the possibilities of cascading rupturing for adjacent fault segments, and space-time evolution characteristics of strong earthquakes in fault systems. 4)The dynamic environment of strong earthquakes in mainland China is characterized by “layering vertically and blocking horizontally”. With the progresses in the studies of geophysics, geochemistry, geodesy, seismology and geology, the physical models of different time/space scales have guiding significance for the interpretations of preparation and occurrence of continental strong earthquakes under the active-tectonic block frame. However, since the movement and deformation of the active-tectonic blocks contain not only the rigid motion and the horizontal differences of physical properties of crust-mantle medium are universal, there is still need for improving the understanding of the dynamic processes of continental strong earthquakes. So it is necessary to conduct in-depth studies on the physical mechanism of strong earthquake preparation process under the framework of active-tectonic block theory and establish various foundation models which are similar to seismic source physical models in California of the United States, and then provide technological scientific support for earthquake prevention and disaster mitigation. Through all kinds of studies of the physical mechanisms for space-time evolution of continental strong earthquakes, it can not only promote the transition of the study of seismic activities from statistics to physics, but also persistently push the development of active-tectonic block theory. 相似文献
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LIMITATION OF CURRENT TECTONIC DEFORMATION MODES IN THE WESTERN MARGIN OF ORDOS BASED ON SEISMIC ACTIVITY CHARACTERISTICS 下载免费PDF全文
下载免费PDF全文 ZHAN Hui-li ZHANG Dong-li HE Xiao-hui SHEN Xu-zhang ZHENG Wen-jun LI Zhi-gang 《地震地质》1979,42(2):346-365
Due to the interaction between the Tibetan plateau, the Alxa block and the Ordos block, the western margin of Ordos(33.5°~39°N, 104°~108°E)has complex tectonic features and deformation patterns with strong tectonic activities and active faults. Active faults with different strikes and characteristics have been developed, including the Haiyuan Fault, the Xiangshan-Tianjingshan Fault, the Liupanshan Fault, the Yunwushan Fault, the Yantongshan Fault, the eastern Luoshan Fault, the Sanguankou-Niushoushan Fault, the Yellow River Fault, the west Qinling Fault, and the Xiaoguanshan Fault.
In this study, 7 845 earthquakes(M≥1.0)from January 1st, 1990 to June 30th, 2018 were relocated using the double-difference location algorithm, and finally, we got valid locations for 4 417 earthquakes. Meanwhile, we determined focal mechanism solutions for 54 earthquakes(M≥3.5)from February 28th, 2009 to September 2nd, 2017 by the Cut and Paste(CAP)method and collected 15 focal mechanism solutions from previous studies. The spatial distribution law of the earthquake, the main active fault geometry and the regional tectonic stress field characteristics are studied comprehensively.
We found that the earthquakes are more spatially concentrated after the relocation, and the epicenters of larger earthquakes(M≥3.5) are located at the edge of main active faults. The average hypocenter depth is about 8km and the seismogenic layer ranges from 0 to 20km. The spatial distributions and geometry structures of the faults and the regional deformation feature are clearly mapped with the relocated earthquakes and vertical profiles. The complex focal mechanism solutions indicate that the arc-shaped tectonic belt consisting of Haiyuan Fault, Xiangshan-Tianjingshan Fault and Yantongshan Fault is dominated by compression and torsion; the Yellow River Fault is mainly by stretching; the west Qinling Fault is characterized by shear and compression. The structural properties of the fault structure are dominated by strike-slip and thrust, with a larger strike-slip component. The near-north-south Yellow River Fault is characterized by high angle NW dipping and normal fault motion.
Based on small earthquake relocation and focal mechanism solution results, and in combination with published active structures and geophysical data in the study area, it is confirmed that the western margin of Ordos is affected by the three blocks of the Tibetan plateau, the Alax and the Ordos, presenting different tectonic deformation modes, and there are also obvious differences in motion among the secondary blocks between the active faults. The area south of the Xiangshan-Tianjingshan Fault has moved southeastward since the early Quaternary; the Yinchuan Basin and the block in the eastern margin of the Yellow River Fault move toward the SE direction. 相似文献
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通过相关分析北京、兰州、银川、红山地磁台地磁垂直分量Z(世界时13—14时)时均值资料(每两台相组合,以月为统计单位),得相关系数R和回归系数b。经统计检验,发现不同台站的R、b大小虽有差异,但正常情况下均在其置信区间变化(置信概率0.95)。几次中强震前,b、R大幅度下降,连续偏离其控制区间,至临震前1—2月或当月趋于恢复或完全恢复。对不同台组的垂直分量差ΔZ与时间作回归分析(ΔZ为时间t的函数),得不同台站的线性回归方程及相关系数R。正常情况下ΔZ在回归方程的置信区间变化(置信概率0.95),当地磁台附近孕育中强以上地震时,ΔZ明显偏离回归方程的控制区间。应用以上两种方法对80年代以来宁夏及其邻区的六次中强地震作了对应效果检验,并对发现的问题作了简略探讨。 相似文献
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分析了近２０年来中国大陆强震（Ｍ≥７．０）和华北地区中强地震前广义前震序列时间和空间分布的多分形特征，计算其广义分维谱Ｄｑ和标度指数谱Ｆ（α），并探讨了它们随时间的变化．结果表明：（１）对广义前震活动，在所研究地区的时、空分布，均呈现多分形结构；（２）大地震发生前半年至一年，地震活动时、空分布的高次分维Ｄ∞呈下降趋势．这种降维特征，亦在实验室含水大样本岩石破坏前，声发射序列Ｄ∞的变化中观测到；（３）与中强地震相比，大地震孕育区地震活动的空间高次分维偏低，表明地壳应力分布的高度不均匀性，是板内大地震孕育环境中的本质因素之一． 相似文献
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In the process of updating existing PSHA maps in Central Asia, a first step is the evaluation of the seismic hazard in terms of macroseismic intensity by applying a data driven method. Following the Site Approach to Seismic Hazard Assessment (SASHA) [11], the evaluation of the probability of exceedance of any given intensity value over a fixed exposure time, is mainly based on the seismic histories available at different locations without requiring any a-priori assumption about seismic zonation. The effects of earthquakes not included in the seismic history can be accounted by propagating the epicentral information through a Intensity Prediction Equation developed for the analyzed area. In order to comply with existing building codes in the region that use macroseismic intensity instead of PGA, we evaluated the seismic hazard at 2911 localities using a macroseismic catalog composed by 5322 intensity data points relevant to 75 earthquakes in the magnitude range 4.6–8.3. The results show that for most of the investigated area the intensity having a probability of at least 10% to be exceeded in 50 years is VIII. The intensity rises to IX for some area struck by strong earthquakes in the past, like the Chou-Kemin-Chilik fault zone in northern Tien-Shan, between Kyrgyzstan and Kazakhstan, or in Gissar range between Tajikistan and Uzbekistan. These values are about one intensity unit less than those evaluated in the Global Seismic Hazard Assessment Program (GSHAP; Ulomov, The GSHAP Region 7 working group [29]). Moreover, hazard curves have been extracted for the main towns of Central Asia and the results compared with the estimates previously obtained. A good agreement has been found for Bishkek (Kyrgyzstan) and Dushanbe (Tajikistan), while a lower probability of occurrence of I=VIII has been obtained for Tashkent (Uzbekistan) and a larger one for I=IX in Almaty (Kazakhstan). 相似文献
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根据华北地区61次中、小地震（3.0≤M≤5.5）和10次M≥6.0大地震的震源机制结果的统计分析,得到地震释能应力场的优势方向,主压应力轴为70°-80°,主张应力轴为340°-350°,它们的仰角基本上小于45°。这表明,华北地区处于以北东东向水平压应力和北北西向水平张应力为主的现代构造应力场中。指出了这一地区6级以上地震和震源深度大于17公里的中、小地震应力场方向一致性较好,可能更接近构造应力场方向。华北地区一致性应力场的南缘,可能在秦岭、大别山及长江下游一带。 相似文献