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通过与更早地震资料的对比, 研究了鲜水河断裂带, 川滇地壳块体东带、 西带, 松潘、 龙门山断裂带以及整个川滇地区较长时间尺度的地震活动盛衰交替性。 结果表明, 川滇东带北段(鲜水河断裂带)、 松潘、 龙门山地震带及川滇西带中段和南段(主要是红河断裂带)的地震活动具有明显的几十到百年尺度的盛衰交替性。 而川滇东带中南段(安宁河-则木河-小江断裂带)与川滇西带北段(金沙江断裂带)在上述地震带的平静期里, 中强以上地震频次明显减少, 但有个别7级以上强震发生。 这样, 整个川滇地区地震活动的盛衰交替性呈现一种比较复杂的阶段性特征: 伴随频繁中强震的强震活跃期与突发强震活动期交替出现。 值得注意的是, 川滇地区从19世纪末开始的伴随频繁中强震的强震活跃期已超过百年, 目前出现长期平静, 应注意进入突发强震活动期的可能性。 根据川滇地区上一个突发强震活动期突发强震的空间分布, 推测未来的突发强震可能发生在南北向断裂带, 或其他方向断裂带与南北向断裂带的交汇部。 文中还对上述统计现象的机理作了简要讨论。 相似文献
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本研究基于分层黏弹介质模型,考虑强震或大地震同震位错、震后黏滞松弛及主断层段震间构造应力加载三方面效应,给出1480年以来,川滇菱形块体东边界鲜水河断裂带、安宁河断裂带、则木河断裂带和小江断裂带共20个断层段由三方面效应引起的累积库仑应力变化随时间的演化,分析强震间相互作用和强震发生的应力累积背景,定性分析各断层段的地震危险性.同时,分别采用现今台网地震目录和川滇菱形块体东边界各断层段强震复发间隔两种资料,定量计算2030年各断层段的强震发生概率;并基于摩擦本构理论,将周边强震引起的库仑应力变化量作为应力扰动,修正强震发生概率的计算结果.各断层段累积库仑应力演化的结果表明,鲜水河断裂带中部八美段、色拉哈段及南部磨西段、安宁河断裂带冕宁-西昌段、小江断裂带北部巧家-东川段和南部建水段的累积库仑应力显著增加.修正的强震发生概率计算结果显示,鲜水河断裂带中部八美-色拉哈-康定一带、安宁河断裂带冕宁-西昌段、小江断裂带南部华宁-建水一带强震发生概率较高,地震危险性值得关注.本研究基于库仑应力演化计算定性分析强震危险性的同时,基于摩擦本构律理论,结合地震引起的应力扰动和强震发生背景,定量计算修正的强震发生概率,为川滇菱形块体东边界强震危险地点及中长期发震紧迫程度判定提供方法和依据. 相似文献
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通过建立较精细的川滇地区三维有限元模型,数值模拟了川滇地区主要活动断裂的强震活动对于其他活动断裂潜在强震孕育进程的库仑破裂应力加卸载效应.模拟结果显示在川滇地区主要活动断裂带的几何学展布形态和运动学性质的构造背景之上,川滇地区强震活动相互影响的主要特征是活动断裂面库仑破裂应力变化大多处于增大状态.其中,金沙江断裂带、小江断裂带、楚雄—建水断裂带、鲜水河断裂带和安宁河断裂带上的强震所产生的加载作用比较强,而丽江—小金河断裂带和腾冲—澜沧断裂带则较弱.1981～2000年川滇地区M≥6.5地震序列的模拟结果显示,后续地震全部位于已发生地震所引起的库仑破裂应力增大区之内.数值模拟结果显示,在川滇地区,一个强震发生之后,发震断层本身强烈卸载的同时,库仑破裂应力的加载效应在其他主要活动断裂带潜在强震孕育进程中占据了主导地位,强震活动之间相互作用的主要效应是应力加载,已发生的强震加速了下一个强震的孕育进程,进而导致一系列地震的发生,直至整个区域所积累的应变能处于较低水平之后,区域地震活动进入一个新的平静期. 相似文献
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通过建立较精细的川滇地区三维有限元模型,数值模拟了川滇地区主要活动断裂的强震活动对于其他活动断裂潜在强震孕育进程的库仑破裂应力加卸载效应.模拟结果显示在川滇地区主要活动断裂带的几何学展布形态和运动学性质的构造背景之上,川滇地区强震活动相互影响的主要特征是活动断裂面库仑破裂应力变化大多处于增大状态.其中,金沙江断裂带、小江断裂带、楚雄—建水断裂带、鲜水河断裂带和安宁河断裂带上的强震所产生的加载作用比较强,而丽江—小金河断裂带和腾冲—澜沧断裂带则较弱.1981~2000年川滇地区M≥6.5地震序列的模拟结果显示,后续地震全部位于已发生地震所引起的库仑破裂应力增大区之内.数值模拟结果显示,在川滇地区,一个强震发生之后,发震断层本身强烈卸载的同时,库仑破裂应力的加载效应在其他主要活动断裂带潜在强震孕育进程中占据了主导地位,强震活动之间相互作用的主要效应是应力加载,已发生的强震加速了下一个强震的孕育进程,进而导致一系列地震的发生,直至整个区域所积累的应变能处于较低水平之后,区域地震活动进入一个新的平静期. 相似文献
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以川滇活动地块东边界为例,利用最近31年的地震资料,根据精细b值计算结果,研究该边界断裂带的应力空间分布及其强震危险性. 研究结果显示：（1）沿川滇活动地块东边界,b值空间分布显示在不同断裂以及同一断裂不同断裂段存在较大差异,从而反映出应力积累水平的空间差异.（2）小江断裂带主干断裂上的嵩明凹凸体及存在于主干断裂附近巧家与东川间以及嵩明北西的2个凹凸体、存在于安宁河断裂冕宁附近和则木河断裂西昌附近的凹凸体以及位于鲜水河断裂中南段道孚—乾宁间大尺度的凹凸体将是川滇活动地块东边界未来大震或强震的震源区. 相似文献
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研究了川滇地区强震活动分布特征及其与地质构造背景，重点是与川滇、川青地壳块体的关系，认为: ①川滇强震主要集中分布在川滇和川青两个地壳块体. 其外侧的中强震活动也明显受这两块体向南东方向滑移侧压的影响；②川滇和川青块体的强震主要分布在边界断裂带上. 块体内部的活断层上也有一些强震或中强震发生. 规模较大的也许是划分次一级块体的边界；③也确有个别强震与活断层关系不明显，表现出地震与地质构造关系的复杂性；④这两块体各边界带的地震活动性，包括盛衰交替性有一定程度的相关性，但也各有特点. 川滇块体东带7级以上地震比西带的多，且最大地震强度达8级，而西带的中强震频度高于东带. 东带的b值低于西带. 无论是地质证据，还是近年GPS观测资料都表明，东带左旋走滑速率都大于西带右旋走滑速率. 川青块体的西边界鲜水河带的地震活动性总的来说高于东边界松潘、龙门山带，且震级越高，差异越大. 前者的b值低于后者. 说明块体各带介质的不均匀性或应力状态是有所不同的；⑤ 川滇和川青块体的边界断裂带在地壳深部速度结构上都有异常变化. 多数边界断裂带切割了莫霍面，尤以倾滑为主的龙门山断裂带切割得最明显. 典型的走滑型鲜水河断裂带虽无切割莫霍面的明显迹象，但确在不同深度上都是明显的低速异常带. 相似文献
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鲜水河断裂带是我国西南地区地震活动最强烈的断裂带。本文通过研究发生在断裂带上强震的震源机制、震源过程、余震分布、地震迁移并结合宏观等震线、地震裂缝分布等资料,研究强震破裂过程与地震活动的关系。研究结果表明:1.鲜水河断裂带的基本破裂方式是左旋走向滑动,强震的压应力主轴存在一致性较好的优势方向,即北东东-南西西方向,且均接近水平。2.用P波频谱及面波方向性函数等研究结果表明,除北西段及南东段几个地震外,七级以上地震及多数六——七级地震的破裂面均为北西向,与鲜水河断裂带的总体走向基本一致。3.1890年以来,鲜水河断裂带强震破裂面展布及1955年以来3.0级以上地震震中分布图表明,在道孚——乾宁间存在的破裂面空段(长约10多km)比1955年以来3.0级以上地震活动缺震段(长约40km)明显的短,这表明1890年乾宁地震破裂面在近期有所愈合。这个缺震段的长度约相当七级左右地震的破裂长度。4.自1890年以来,带上发生的四个七级以上地震有两头迁移的特点。考虑到最后一次七级地震是1973年的炉霍地震,估计下次七级地震的位置在南东段,且在道孚——乾宁间的可能性最大。 相似文献
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鲜水河断裂是高频度的强震发生带,1981年道孚地震后,未来的强震往何处迁是地震预报以及地震区划研究中的重要课题。本文从断错地貌,滑动速率,大震同震位错以及断裂带上地震滑动模式的讨论出发,运用地质学方法寻找鲜水河断裂带上直到本世纪末的潜在震源区。结果表明,道孚以南松林口—惠远庙之间长达40公里的地段是发生M≈7级地震的可能性最大的潜在震源区,而康定断裂的北段也值得重视。 相似文献
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《地震地质》2017,(3)
采用分层黏弹模型,考虑了川滇菱形块体东边界1480年以来34个强震和大地震的同震位错和震后黏滞松弛效应,以及各断层段的震间长期构造加载作用,计算了川滇菱形块体东边界18个断层段的断层面上的库仑应力变化随时间的演化。系统地研究了川滇菱形块体东边界鲜水河、安宁河、则木河、小江断裂带间的相互作用,分析断裂带各断层段之间、各断裂带之间先发生的地震对后发生地震的促进或延迟作用,进一步基于断层面上的库仑应力变化计算结果分析各断层段的强震危险性。应力触发的计算结果显示,各断裂带各断层段上先发生的强震可能触发后发生的强震,相邻断裂带上发生的强震之间也可能存在触发作用。各断层段上累积库仑应力变化随时间演化的计算结果显示,鲜水河断裂带的中段及南部磨西段、安宁河断裂带冕宁—西昌段、小江断裂带北部巧家—东川段和南部建水段的库仑应力增加显著,强震危险性值得关注。 相似文献
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S.Thomas Crough 《Physics of the Earth and Planetary Interiors》1977,14(4):365-377
The lithosphere is interpreted as a thermal boundary layer. Approximate solutions of the boundary layer cooling problem are developed which include mantle radioactivity, partial melt in the asthenosphere, a temperature gradient in the asthenosphere, and a non-zero lithospheric thickness at the ridge crests. The cooling history of oceanic lithosphere is found to be remarkably insensitive to assumptions about the amount of radioactivity in the upper mantle and the extent of melting in the asthenosphere. Determinations of the thickness of oceanic lithosphere and the depths of oceans as a function of age are in excellent agreement with boundary layer predictions which include a heat flux from the asthenosphere. However, the determinations do not resolve how much of the total asthenospheric heat flux might be caused by a temperature gradient in the asthenosphere. Simple thermal arguments indicate that the initial lithospheric thickness, L0, at ridge crests should depend on the local half-spreading rate, V, as L0 = 3 km/V(cm/year). 相似文献
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Kostelecký J. Kostelecký J. Pešek I. Šimek J. Švábenský O. Weigel J. Zeman A. 《Studia Geophysica et Geodaetica》2004,48(3):503-518
Several quasigeoid models for the Czech Republic have been developed for different purposes since mid-seventies using different data sources: gravimetric, astronomical and GPS/levelling observations, as well as data gained from the territories of neighbouring countries. Two of the recent solutions, namely the VUGTK96 quasigeoid obtained from heterogeneous data and gravimetric quasigeoid CR2000 are described and compared. Accuracies of the models were estimated with the help of accuracy characteristics resulting from the processing, by comparison with GPS/levelling results available for most of the territory, and, finally, tested on a special GPS/levelling profile across the steepest slope of the quasigeoid surface in the south-eastern part of the territory. It is shown that the CR2000 gravimetric quasigeoid is suitable for transformation of ellipsoidal GPS heights to the gravity related heights with an accuracy of 3 cm. 相似文献
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Biosecurity management allows countries to meet a number of international obligations and provides some protection from potential degradation of environmental, economic, social and cultural values. Ocean governance relies on the precepts of ecologically sustainable development to manage the multiple uses in the coastal zone. The increasing reliance on aquaculture to provide food security and economic development has led to an increase in the use of non-native target species grown as food sources. Increased economic activity has led to shifting trade patterns and increased efficiencies in vessels with the resulting increase in the number of introduced marine species via ballast water and hull fouling. Herein we review the different marine biosecurity strategies and legislation that have been implemented internationally and locally that aid in preventing and managing introduced marine species, with some attention to Australia and New Zealand as examples. Typical tools being used include quarantine, Import Health Standards, voluntary cleaning guidelines, and risk assessment, all of which aim to prevent introductions. 相似文献
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Ten Years of Development of Equipment for Measurement of Atmospheric Radioactive Xenon for the Verification of the CTBT 总被引：1，自引：0，他引：1
Matthias Auer Timo Kumberg Hartmut Sartorius Bernd Wernsperger Clemens Schlosser 《Pure and Applied Geophysics》2010,167(4-5):471-486
Atmospheric measurement of radioactive xenon isotopes (radioxenon) plays a key role in remote monitoring of nuclear explosions, since it has a high capability to capture radioactive debris for a wide range of explosion scenarios. It is therefore a powerful tool in providing evidence for nuclear testing, and is one of the key components of the verification regime of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The reliability of this method is largely based on a well-developed measurement technology. In the 1990s, with the prospect of the build-up of a monitoring network for the CTBT, new development of radioxenon equipment started. This article summarizes the physical and technical principles upon which the radioxenon technology is based and the advances the technology has undergone during the last 10 years. In contrast to previously used equipment, which was manually operated, the new generation of radioxenon monitoring equipment is designed for automated and continuous operation in remote field locations. Also the analytical capabilities of the equipment were strongly enhanced. Minimum detectable concentrations of the recently developed systems are well below 1 mBq/m3 for the key nuclide 133Xe for sampling periods between 8 and 24 h. All the systems described here are also able to separately measure with low detection limits the radioxenon isotopes 131mXe, 133mXe and 135Xe, which are also relevant for the detection of nuclear tests. The equipment has been extensively tested during recent years by operation in a laboratory environment and in field locations, by performing comparison measurements with laboratory type equipment and by parallel operation. These tests demonstrate that the equipment has reached a sufficiently high technical standard for deployment in the global CTBT verification regime. 相似文献
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对大同－阳高地震的地磁场△Ｆ时、空变化做了分析。认为６．１级地震前８个月山西北部地磁场△Ｆ出现异常，同年９月达高潮。６．１级地震后的１９９０年３月地磁场活动又出现了第２次高潮。２次高潮的异常幅度分别为１３．０ｎＴ和１３．２ｎＴ。大同－阳高地震的地磁异常具有时段长，连续性好，空间分布广的特点。 相似文献
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Frank M. Richter 《Earth and Planetary Science Letters》1984,68(3):471-484
Traditional models for the heat loss in oceanic and continental regions are combined into a regionalized model for the thermal evolution of the Earth. The need for regionalization is obvious when one considers that the mantle loses 3 to 4 times as much heat per unit area in oceanic regions than in continental areas. The present-day rate of heat loss together with a geochemical estimate of the concentration of heat-producing elements in the Earth fixes the response time of the thermally convecting mantle. The response time in turn can be used to select the most reasonable representation for mantle convection in terms of the sensitivity of viscosity on temperature and layering versus mantle-wide circulation. Present geochemical estimates of the bulk composition of the Earth are most easily reconciled with the observed heat flow if the mantle is layered and its rheology is slightly less temperature dependent than generally assumed. The layered system can produce sufficiently high temperatures to explain the high-magnesian komatiites of the Archean. One difficulty with the models is that they predict widespread melting at shallow depth in the early stages of Earth history but do not address how such melting affects and alters the heat transfer mechanisms. 相似文献
18.
G.R. Dargahi-Noubary 《Physics of the Earth and Planetary Interiors》1983,33(2):91-93
A procedure is described for estimation of the maximum feasible magnitude for earthquakes in a given region. This procedure provides a confidence interval for the upper bound without the need for any numerical calculation. 相似文献
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Methodology for the development of analytical fragility curves for retrofitted bridges 总被引：1，自引：0，他引：1
Fragility curves for retrofitted bridges indicate the influence of various retrofit measures on the probability of achieving specified levels of damage. This paper presents an analytical methodology for developing fragility curves for classes of retrofitted bridge systems. The approach captures the impact of retrofit on the vulnerability of multiple components, which to date has not been adequately addressed, and results in a comparison of the system fragility before and after the application of different retrofit measures. Details presented include analytical modeling, uncertainty treatment, impact of retrofit on demand models, capacity estimates, and component and system fragility curves. The findings indicate the importance of evaluating the impact of retrofit not only on the targeted response quantity and component vulnerability but also on the overall bridge fragility. As illustrated by the case study of a retrofitted multi‐span continuous (MSC) concrete girder bridge class, a given retrofit measure may have a positive impact on some components, yet no impact or a negative impact on other critical components. Consideration of the fragility based only on individual retrofitted components, without regard for the system, may lead to over‐estimation or under‐estimation of the impact on the bridge fragility. The proposed methodology provides an opportunity to effectively compare the fragility of the MSC concrete bridge retrofit with a range of different retrofit measures. The most effective retrofit in reducing probable damage for a given intensity is a function of the damage state of interest. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
20.
A simplified suspended growth integrated system with an anaerobic zone in front of the aerobic one was used for the development of the bacterium Acinetobacter for phosphorus removal. The pilot plant experimental equipment was built at the Prague municipal works. The tests were carried out on a comparative basis, the control system was operated as a completely mixed activated sludge process. In the integrated system a to phosphate removal of 80 to 86% was achieved only in a biological way. In the control system, there was no development of Acinetobacter and the biological phosphate removal was only 5%. To rise it to the extent comparative with the integrated system, high doses of ferric chloride for a simultaneous precipitation of phosphate were required. The results obtained showed that the strictly biological process in the integrated system could meet normal practice requirements, even though it is not able to compete with the simultaneous phosphate precipitation using high coagulant dosages as for as the attainable efficiency and higher values of the sludge index are concerned. 相似文献