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1.
中国大陆地震活跃期和平静期的b值与地震趋势研究   总被引:2,自引:0,他引:2  
计算了中国大陆5个地震活跃期和4个地震平静期的b值。地震活跃期的b值明显比地震平静期的b值低,地震活跃期的b值为0.72~0.76,平均为0.75,地震平静期的b值为0.86~1.06,平均为0.97。截止到2000年3月,第五轮回的活跃期b值为0.87,介于地震平静期与地震活跃期的平均值之间,明显高于地震活跃期的b值。因此,中国大陆从1 988年开始的第五轮回的地震活跃期可能还没有结束,还可能发生较大的(7级)地震。  相似文献   

2.
本文基于匹配滤波技术,通过SEPD(Seismic Events and Phase Detection)对2018年11月25日新疆博乐MS4.9地震序列进行检测,检测出遗漏地震32条,84.4%地震为ML0.0—1.0,9.4%地震小于ML0.0,较地震目录中原有15条地震多213%,检测出的遗漏地震事件使地震目录更加完整。检测后的最小完整性震级由检测前的ML1.6减至ML0.8,地震目录最小完整性震级的减小有利于地震工作者对区域地震活动性作出更准确全面的结论,并使地震危险性分析更可靠。  相似文献   

3.
叙述井分析了山西地震带地质构造特点和近期的中强地震及震群活动基本特征,在此基础上,与大同一阳高地震进行了分析对比,认为大同-阳高地震是山西地震带近期地震活动的继续,而山西地震带今后强震活动阶段的开始,其标志应是NVE向新生代断陷内的中强地震活动,因此在分析和预估山西地震带今后地震发展趋势时,应密切注视这一地带的地震活动。  相似文献   

4.
地震信息传播已进入实时、全面、多维的公共服务时代,单一媒体地震信息服务已无法满足政府、社会公众和地震行业需求,地震信息向融媒体公共服务模式发展。本文对地震信息内容服务需求及特点、地震媒体平台功能特色、融合式媒体信息服务模式等进行分析,对地震信息融媒体公共服务进行研究,旨在提高地震信息服务效率与用户满意度,促进地震信息化建设科学、健康发展。  相似文献   

5.
赵邦学 《地震学刊》2001,21(4):39-49
按地震在空间上的相似活动过程排列的华北与闸粤沿海及银川地震区(带)地震活动周期表,以华北地震活动为主线,将公元前280年咸阳51/2级地震至1988年2月25日彰武4.8级地震间2267件的华北地震活动划分为4个时间层次。其组合关系是,一个超长地震周期由初,前,主,余霞期4个地震期组成;除前震期只有一个地震周期外,初,主,余震期都包含前弱后强两个地震周期;每个地震周期多分为初,前,主,余霞震4个地震段。闽粤沿海地震区和银川地震带的主震段分别与华北初,余震段同期活动。地震周期是介于前人划分的地震幕与地震活动期之间一个新的更为重要的时间层次。华北7个地震周期的起止时间是:-280.50-8.22-80.12-1337.69-1568.37-1730.75-1855.95-1988.15年,并从时空强3方面阐述了华北地震周期性活动规律,分析了3个地震区,带地震周期的相互关系。华北地震周期可作为标准地震周期与不同地区地震周期相对比,具有重要的预报意义。  相似文献   

6.
本文简述了我国地震标准化发展从无到有、从小到大经历的4个主要阶段,基于地震标准发布实施时间及业务领域分布统计对地震标准现状进行详细分析,阐述我国现行地震标准特点和存在的问题。在进一步研究地震标准体系的基础上,提出了完善建议,并初步构建了新的地震标准体系框架。通过对现行地震标准和标准体系的分析,提出地震标准化思考与建议,以期为进一步推进地震标准化工作提供借鉴。  相似文献   

7.
吴忠良  蒋长胜 《中国地震》2006,22(3):236-241
地震前兆的效能检验问题既是地震预测研究中的一个基本问题,也是近年来围绕地震预测问题的一个争论焦点。传统的地震预测研究中关于地震前兆机理的一个基本假定,即地震前兆来自地震孕育过程中应力场的某种变化,与传统的地震前兆检验方案,即针对“异常”信息统计与地震之间的“对应”情况,并进行统计显著性检验,存在一个内在的逻辑矛盾。地震前兆的检验不是一个简单的统计问题,而是一个地球动力学问题,不考虑地球动力学的地震前兆检验是没有意义的,由此得到的检验结果则可能对相关研究造成误导。  相似文献   

8.
钱晓东  秦嘉政 《地震》2006,26(2):113-121
利川判断地震序列能蕈释放衰减是否异常的Ec—k量板,汁算了云南及附近地区39次巾强地震序列的能量衰减系数k值。结果显示:①当判别指标k〉1时,地震序列能量衰减处于正常状态;当k≤1时,判断地震序列能量衰减出现异常,其后发生更大地震或强余震的町能什较大。②对云南地区中强地震序列的榆验表明,有74%的地震序列符合上述判别指标。③用相同的地震进行了地震序列频度衰减系数^值的计算,发现符合h值判别指标的地震序列占统计际本的锄%。④对日常地震跟踪临视中遇到的二次典型地震序列详细分析,发现用k值力。法无论对中小地震序列还是巨震序列,预测效果均较好。  相似文献   

9.
分析了2004年3月24日内蒙古东乌珠穆沁旗5.9级地震前东北地区地震活动背景、震中周围中小地震活动图像和地震学参数异常过程。在地震发生前,震中及邻区地震活动明显增强,地震活动从无序到有序,出现了孕震空区、地震条带。一些地震活动性参数出现了中、短期异常。  相似文献   

10.
根据滇西地震带大理─剑川段地震活动特征,把公元1498~1991年M≥4.7级地震迁移分为4期。每期地震迁移均以洱源地区的地震为先导,洱源先导地震震级越大,全段地震活动水平就越高,反之亦然。文中从地下水对断裂的弱化的角度,讨论了地震迁移规律及原因。洱源地区地下水对其断裂弱化的程度最高,其断裂最薄弱。这样,在区域应力场的作用下,最薄弱的洱源地区必将首先破裂而发震,所以每期地震迁移均以洱源地区的地震为先导。认为洱源地区的地震活动特征可以作为预测全段地震活动水平的“窗口”,大理地区在今后5年左右的时间内(即1996年前后)有发生6级左右地震的可能性。  相似文献   

11.
The performances of kriging, stochastic simulations and sequential self-calibration inversion are assessed when characterizing a non-multiGaussian synthetic 2D braided channel aquifer. The comparison is based on a series of criteria such as the reproduction of the original reference transmissivity or head fields, but also in terms of accuracy of flow and transport (capture zone) forecasts when the flow conditions are modified. We observe that the errors remain large even for a dense data network. In addition some unexpected behaviours are observed when large transmissivity datasets are used. In particular, we observe an increase of the bias with the number of transmissivity data and an increasing uncertainty with the number of head data. This is interpreted as a consequence of the use of an inadequate multiGaussian stochastic model that is not able to reproduce the connectivity of the original field.  相似文献   

12.
Stemflow of a dry sclerophyll eucalypt forest and a nearby Pinus radiata plantation was studied on a rainfall event basis. The stemflow yields of the forests are quantified, compared, and presented on an annual basis for four years. Yields of the individual eucalypt species are compared and the tree characteristics responsible for the yield differences are discussed. The influence of event size, type, and season on stemflow are also shown. Rainfall angle is shown to have a significant effect on stemflow yield.  相似文献   

13.
光纤Bragg光栅在油气工业中的若干应用及进展   总被引:1,自引:2,他引:1       下载免费PDF全文
简要介绍光纤Bragg光栅的基本原理、传感检测系统的构成,以及利用光纤Bragg光栅进行温度、应变同时测量区分技术.光纤光栅作为新一代传感元器件,越来越受到广大油气工业用户的青睐.本文主要讨论光纤Bragg光栅在油气工业中的若干应用,并对存在问题和应用前景进行了展望.  相似文献   

14.
在地磁学与地球重力学中的球谐分析   总被引:6,自引:5,他引:1       下载免费PDF全文
球谐分析在地磁学与地球重力学中得到广泛的应用.由于地球磁场与地球引力场的不同,球谐表述有所不同.地磁场的高斯分析(球谐分析)的结果表明,地磁场没有单极子,而引力场有,地磁场有内外源场之分,而地球引力场只有内源场,地磁场的球谐级数收敛快,地磁场高斯级数所用的蒂合勒让德函数是Schmidt半标准化的,而地球引力场中用的是全标准化的,地磁场的高斯系数随时间变化快,每5年产生一个IGRF(国际地磁参考场), 而引力场的变化是与地质变化有关,相对于地磁场来说,是缓慢的. 地磁场的高斯分析还存在一个唯一性问题.  相似文献   

15.
Several two-dimensional structures are modelled for vertical electrical soundings in arrays parallel and perpendicular to the strike of the structure. The models are a horst and a graben within a three-layer medium, a cliff over two layers, and heterogeneities around the electrodes. Apparent resistivity curves are shown for different model parameters and different distances to the two-dimensional structures. Some of the features on the shape of these curves are inflections that may be misinterpreted as fictitious layers, of slopes greater than 45°; some features are simply anomalous peaks. One-dimensional interpretation of a two-dimensional graben model has been performed, in order to show typical errors when 2D structures are interpreted as one-dimensional. A real case corresponding to a landfill near Barcelona and showing strong lateral and topographic effects is presented. This represents combined effects of the above theoretical 2D models.  相似文献   

16.
Palaeofluid-transporting systems, observed as networks of mineral-filled veins in deeply eroded parts of extinct geothermal fields, indicate that hydrofractures commonly supply fluids to geothermal fields. Here we examine well-exposed vein networks that occur at crustal depths of around 1.5 km below the initial surface of the Tertiary lava pile in North Iceland. The veins are located in the damage zone of a major fault zone that dissects basaltic lava flows, the most common host rocks of geothermal fields in Iceland. The lava flows contain numerous weaknesses, particularly columnar (cooling) joints and contacts. For hydrofractures to supply fluids to geothermal fields, the fractures must be able to propagate, and transport fluids, to the surface. We explore hydrofracture pathway formation using boundary-element models of hydrofractures with fluid overpressure varying linearly from 10 MPa at the fracture centre to 0 MPa at the fracture tip (or the fluid front). The hydrofractures propagate through a vertically jointed and horizontally layered pile of lava flows with a general rock-matrix Young’s modulus of 1×1010 Pa and a Poisson’s ratio of 0.25. The joints and contacts between layers are modelled as internal springs, each with a stiffness (‘strength’) of 6 MPa/m. The location and sizes of discontinuities, as well as the location of the hydrofracture tip, vary between the models. The results indicate that tensile stresses generated at the tip of an overpressured hydrofracture can open up horizontal and vertical discontinuities out to a considerable distance from the tip, and that these discontinuities eventually link up to form the hydrofracture pathway. Analytical models indicate that for a hot spring of a given yield associated with a fault, the dimensions of the fluid-transporting part of the fault are likely to be similar for a typical normal fault and a strike-slip fault. Also, a hot spring of yield 180 l/s (the maximum in the low-temperature fields of Iceland) can be supplied through a hydrofracture of aperture 3 mm and trace length 1.2 m. These dimensions are very similar to those of typical veins in the studied networks. Buoyancy, rather than excess pressure in the fluid source, appears to be the primary driving force of hydrofractures in the geothermal fields of Iceland.  相似文献   

17.
Rossby wave patterns in zonal and meridional winds   总被引:1,自引:0,他引:1  
The propagation properties of Rossby waves in zonal and meridional winds are analyzed using the local dispersion relation in its wave number form, the geometry of which plays a crucial role in illuminating radiation patterns and ray trajectories. In the presence of a wind/current, the classical Rossby wave number curve, an offset circle, is distorted by the Doppler shift in frequency and a new branch, consisting of a blocking line with an eastward facing indentation, arises from waves convected with or against the flow. The radiation patterns generated by a time harmonic compact source in the laboratory frame are calculated using the method of stationary phase and are illustrated through a series of figures given by the reciprocal polars to the various types of wave number curves. We believe these results are new. Some of these wave patterns are reminiscent of a “reversed” ship wave pattern in which cusps (caustics) arise from the points of inflection of the wave number curves; whilst others bear a resemblance to the parabolic like curves characteristic of the capillary wave pattern formed around an obstacle in a stream. The Rossby stationary wave in a westerly is similar to the gravity wave pattern in a wind, whereas its counterpart in a meridional wind exhibits caustics, again arising from points of inflection in the wavenumber curve.  相似文献   

18.
The results of an instrumental and analytical investigation of the products of mineral and textural transformations in the tectonic slickensides and fault gouge in the near-surface terrigenous sedimentary rocks (clays, arkose sandstones, shungites) which have undergone localized deformations in fault zones of presumably seismogenic origin are presented. Based on this, several peculiarities in the behavior of a dynamic slip in the upper transition horizon from aseismic to seismogenic mode of faulting in the Earth’s crust are elucidated. The changes in the mineral phase compositions of the fault facies against the protolith composition are estimated; the parameters of the temperature regime and thermal energy balance of deformational metamorphic reactions are determined. The probable causes of instability in the faults, the mechanisms of the loss of strength, the weakening and strengthening during seismogenic dynamic slip are considered. The role of tribochemical phenomena in the course of a rock’s transformation into a fault gouge and the related energy effects are discussed. An inventory of the possible energy costs on the processes of transforming material in dynamic slip zones is compiled.  相似文献   

19.
The abundances of zirconium and hafnium have been determined in nine stony meteorites by a new, precise neutron-activation technique. The Zr/Hf abundance ratios for the chondrites vary in a rather narrow range, consistent with previously published observations from our group. Replicate analyses of new, carefully selected clean interior samples of the C1 chondrite Orgueil yield mean zirconium and hafnium abundances of 5.2 and 0.10 ppm, respectively. These abundances are lower than we reported earlier for two C1 chondrite samples which we now suspect may have suffered contamination. The new C1 zirconium and hafnium abundances are in closer agreement with predictions based on theories of nucleosynthesis than the earlier data.  相似文献   

20.
The concentrations of 25 major, minor and trace elements have been determined in four clasts, a metal-rich inclusion and two dark metal-poor inclusions from the Abee enstatite chondrite. The clasts are heterogeneous, displaying 2-fold enrichments or depletions in some elements. The data suggest that there are two generations of metal, one with low, the other with high concentrations of refractory siderophiles. The other elemental patterns can be understood in terms of variations in the abundance of major minerals. We infer that Sc and Mn are located largely in the niningerite ((Fe,Mg)S), V in the troilite (FeS) and rare earth elements in the oldhamite (CaS).Heterogeneities among the clasts are probably primary, resulting from the accretion-agglomeration process, although shock processes in a regolithic setting remain a possibility provided that they were followed by a period of metamorphism sufficient to erase petrologic evidence.In the dark inclusions the concentrations of the rare earths, Eu excepted, are 4 × higher than mean EH levels; this infers enhanced amounts of CaS. The dark inclusions are low in siderophiles, Sc, Mn, K, Na and Al, implying low amounts of metal, niningerite and feldspar. The origin of the dark inclusions is unclear; they do not appear to be the result of a simple, single-stage process.  相似文献   

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