共查询到20条相似文献，搜索用时 31 毫秒
1.
We study temporal changes of the rigidity (R) spectrum of the harmonics of the 27-day variation of the galactic cosmic ray (GCR) intensity using neutron monitors (NM) data for the period 1965–2002. We show that the rigidity spectrum of the third harmonic (9 days) of the 27-day variation of the GCR intensity changes in a similar way as the spectra of the first and second harmonics, being hard in the maximum epochs and soft in the minimum epochs of solar activity. We ascribe this finding to the alternation of the sizes of the modulation regions of the 27-day variation of the GCR intensity in different epochs of solar activity. The average size of the vicinity of the corotating interaction regions, causing the 27-day variation of the GCR intensity, is less in the minimum epochs than in the maximum epochs of solar activity. A vicinity of the corotating interaction regions of larger size involves in modulation higher rigidity particles of GCR than the vicinity of smaller size; thus, this statement can be considered as one of the reasons leading to the hardening of the rigidity spectrum of the harmonics of the 27-day variation of the GCR intensity in maximum epochs compared with minimum epochs of solar activity.We also show that the temporal changes of the power rigidity spectrum of the third harmonic of the 27-day variation of the GCR intensity are negatively correlated with the rigidity spectrum of the 11-year variation of the galactic cosmic ray intensity.We found a recurrence in the temporal changes of the amplitudes of the first harmonic of the 27-day variation of the GCR intensity and in some parameters of solar activity and solar wind. 相似文献
2.
Summary Three important characteristics of the stochastic relation between the position of one point of a geodetic network and the positions of the remaining points are investigated: a) Change of the ellipse of confidence of the position of a point of the network to the ellipse of confidence of the position of a point of the network, relative to any other point of the network. (This characteristic is called the change of the global ellipse of confidence to the relative ellipse). b) The regression between the positional vector of the investigated point and the positional vectors of some group of other points of the network and c) the so-called total correlation between any two points of the network. The latter characteristic is a question of determining a characteristic direction for each pair of investigated points, which would have the property that the correlation coefficient between the random displacement of the first point in its characteristic direction and the random displacement of the second point in its characteristic direction is maximum. 相似文献
3.
The study of magnetization of the ceramic material from 21 archeological monuments of Portugal (the Evora province), dated archeologically from the Bronze Age to the end of the Iron Age has been carried out. For the purpose of more detailed timing of the material from the monuments the method of ceramic age dating on the basis of its porosity has been used. In order to take into account the distorted factors in the determination of the parameters of the ancient geomagnetic field with the aim of the maximal approximation to the actual values the diagnostic features of magnetite weathering have been considered and the level of weathering of the magnetic fraction in the ceramics from archeological monuments has been determined. The data of geomagnetic field-strength variation in the time interval of the 12th century BC to the beginning of the Common Era have been obtained. The field-strength at this time interval varied in the range of 60–90 micro Tesla with the maximal values in the 9th, 8th, and the second half of the 5th to the beginning of the 4th century BC. In addition, the timing of the ceramic material from the urns of the megalithic complex Monte de Tera of the Evora province has been clarified. 相似文献
4.
本文介绍利用地震转换波测深法研究1976年7.8级唐山大震区深部构造的某些结果,得出了沿两条测线的深部构造剖面图。发现在极震区的数十公里的范围内,地壳和上地幔具有异常结构,在地壳中部比震区外围多出一个中间层位,埋深约12-20km,地壳上部界面向上挠曲,而莫霍面和上地幔顶部界面却强烈地向下挠曲,引起了震区岩石圈厚度的加大,在震区存在深浅不等的深部断裂。深部构造与震源分布的对比表明,唐山主震和绝大多数余震均分布在壳内中间层之上,有的甚至就分布在壳内中间层的上、下界面附近。转换波测深结果表明,本区地壳上地幔中强烈的升降差异运动可能是唐山大震的重要促发因素。 相似文献
5.
为解决传统建筑沉降变形中存在的幕墙结构易发生变形、稳定性较差等问题,提出建筑沉降变形中幕墙结构屈曲稳定临界荷载的研究。选取框架玻璃幕墙作为研究对象,建立玻璃面板的有限元模型,分别从X、Y、Z三个方向对玻璃面板施加平动自由度约束力,进行幕墙结构屈曲稳定临界荷载的模拟;然后在建筑底部不同节点处设置竖向弹簧,通过调节弹簧刚度模拟建筑沉降变形的竖向作用力,在此基础上,采用能量法分别计算玻璃肋的应变势能、外力势能和弹性约束势能,根据势能驻值原理计算得出建筑沉降变形中幕墙结构屈曲稳定临界荷载;最后设置不同的玻璃肋参数,选取单一变化因素进行实验。实验结果表明:在不同玻璃肋跨度和截面厚度对比下,所提方法的计算结果较为准确,且所提方法的临界荷载计算耗时低于其他方法,具有较高的实际应用价值。 相似文献
6.
The results of a study of the macroseismic effects in the territory of Moscow of a remote deepfocus earthquake that occurred on May 24, 2013 in the Sea of Okhotsk are reported. On the surface of the earth and on the first floors of the buildings the seismic effect was not felt. The effect of the shock began to manifest itself at levels higher than the fifth floor of the buildings. The distribution of points on the map where the earthquake was felt is non-uniform. Points where tremor was felt do not appear to correspond with certain types of Quaternary deposits or with zones of different depth. There is also no significant correlation of the parts of the surface with high intensities of tremor and areas of ground-water flooding. Comparison between the surface manifestations of the seismic event and the tectonic features and deep structure of the metropolis was made. Based on the results of the implemented statistical estimation of distribution points where the earthquake was felt on the territory of the city it is visible that fault zones govern the largest number of points, while block structures characterize almost half of them. Thus, we can reasonably suggest a certain macroseismic increase of vibrations from earthquakes in the areas of large faults in the city. The study of deformations of the asphalt cover of walkways on the landslide-affected slope of Vorobyovy Hills showed that the tremor caused by the Okhotsk deep focus earthquake of May 24, 2013, caused the activation of a small landslide at all levels of the hillside. 相似文献
7.
According to the data of the IMAGE network of magnetometers the latitudinal profile of the amplitude of the Pc5 geomagnetic
pulsations is constructed, which are excited in the Earth’s magnetosphere in the form of the resonance Alfvén magnetohydrodynamic
pulsations. The approaches to the solution of two problems are studied on a specific example. The first concerns the anharmonicity
of Alfvén’s resonances. The displacement of the peak of the resonance curve towards to the north with the reduction of the
amplitude of the pulsations is discovered. Based on the results of measurements, the nonlinear distortion coefficient of the
latitudinal profile is determined. The second problem is connected with the magnetotelluric sounding. Information about the
resonance structure of the Alfvén pulsations is useful for magnetotelluric sounding. This information gives the possibility
of evaluating the accuracy of the sounding with the application of the local impedance relationship and of introducing corrections
if necessary. 相似文献
8.
Karel Prikner Jaroslay Střeštík Karel Dobeš Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1973,17(4):337-345
Summary Using the method of two-component spectral analysis of planar oscillation events by means of computer processing of A-t records, a series of about 100 samples of geomagnetic beating-type pulsations pc3 was treated. The quantitative data obtained on the internal structure of the pulsations (frequency spectra and polarization characteristics) were treated statistically. The pattern of the daily variations of the frequencies and amplitudes of the fundamental amplitude-dominating frequency components of the pulsations and the daily variations of the polarization characteristics of these components, the ellipticity of the polarization ellipses, the directions of the main axes of these ellipses and the sense of rotation of the disturbance vector along the ellipses were obtained.A part of the results was reported at the XVth General Assembly of the IUGG, Moscow, August 1971. 相似文献
9.
The GALO basin modeling system has been applied for the numerical reconstruction of the subsidence history, variations in temperature, and maturity of the organic matter of sedimentary rocks composing the main tectonic structures of Sirte Basin. The reconstruction was carried out for eight sedimentary cross sections along the profile stretching from the Cyrenaica Platform on the eastern coast of the basin to the Hun Graben on its western wall. The interval of depths for temperature calculations included the sedimentary layer, consolidated crust, and the mantle to below 100 km. This extensive depth coverage made it possible to use the analysis of the variations in the tectonic subsidence of the basin for estimating the amplitudes and duration of the events of thermal activation and extension of the lithosphere of the basin in the history of its evolution. The modeling suggests that thermal activations of the lithosphere in the Albian-Cenomanian and Oligocene-Pleistocene are common for all tectonic structures of the Sirte Basin and the Cyrenaica Platform and that a relatively high temperature regime is also characteristic of the present-day conditions in the Sirte Basin and Cyrenaica Platform. To a considerable extent, such a regime is caused by the thermal activation of the lithosphere of the basin during the last 10 Ma. The intensity of this activation is highest in the western part of the basin, where it is accompanied by the highest erosion amplitudes. The analysis of the variations in tectonic subsidence of the basement also suggests a series of intervals of lithospheric extension, which accounts for the stages of relatively rapid subsidence of the basin. Two intervals of significant extension of the lithosphere in the Upper Cretaceous and Paleocene are common for all areas within the basin. Here, the total amplitudes of the crustal extension attained 1.5 in the central part of the Sirte Basin (the Ajdabiya and Maradah troughs and Zelten and Dahra platforms), was equal to 1.3 in the Hameimat and Zallah troughs, and were minimal (1.11–1.17) in the periphery of the basin (within the Hun Graben and Cyrenaica Platform). 相似文献
10.
共搜集到１９６０￣１９９０年中、南美洲地区１０个地震序列。其中１个是板内地震序列。这个板内地震序列表现出的特征是：震中分布区域的长轴较短,长短轴之比低;余震震源机制和主震震源机制相比变化大。其余９个是俯冲带上的板缘地震序列,它们的共同特征是：震中分布区域的长轴较长;震源深度下限超过地壳,可以达到７０ｋｍ以下（第１０号序列例外）;主震的震源机制受俯站带的走向、倾向和倾角的控制。但是这些震序列又分为两 相似文献
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12.
A. M. Bobrov 《Izvestiya Physics of the Solid Earth》2010,46(6):477-485
The distribution and time evolution of overlithostatic horizontal stresses in the vertical cross-sections of the model of
a solid continent are studied in terms of a 2D numerical model. The continent is moving self-consistently with time-varying
mantle flows. Over a period of 50 Ma, the continent, which had been initially located at a distance of about 1500 km from
the downward mantle flow (subduction zone), first overlays the region of the marginal sea, then thrusts over the zone of subduction,
thus making it inclined and deforming it. It is found that the horizontal tensile stresses observed at the initial stages
are succeeded by compressive stresses, especially at the leading edge (up to 40 MPa). This is caused by the change of the
dragging action of the subduction zone into the retarding action during the continent crossing over this zone. The dependence
of the calculated stresses on the Rayleigh number and on the thickness of the model of the continent is estimated. It is obtained
also that the distribution of horizontal stresses along the strike of the continent is rather distinctly indicative of the
locations of upward and downward flows in the subcontinental mantle. With the considered values of the model parameters, the
tensile stresses in the near-to central regions of the continent may be twice to thrice the tensile stresses at its margins.
Hence, in the simplest case of a homogeneous continent, its division will occur in the zone directly above the upward subcontinental
flow. Detachment from the continent of the fragments of its edge adjacent to the marginal sea implies that the thickness of
the continental plate in that part and/or its strength is considerably lower than in the center of the continent. 相似文献
13.
通过大型地质力学模型试验,研究在无支挡结构下降雨对隧道-滑坡正交体系的作用机理。主要研究不同降雨阶段,隧道-滑坡正交体系下隧道纵向应变的变化特征及隧道不同横断面环向应力变化特点,并重点分析在不同降雨阶段,不同位置及其不同横断面滑体的位移变化特征。试验结果表明:(1)降雨可导致坡体横断面断裂而出现新的滑移面,从而导致坡体失稳。(2)在隧道-滑坡正交体系下,随着雨水的下渗及滑体土样含水率不断增大,隧道局部应变有明显突变,且山侧纵向应变比河侧应变要大。(3)在隧道-滑坡正交体系下,降雨使得隧道环向应力呈不均匀变化:隧道的底部应力大于顶部应力,山侧应力大于河侧应力,表明降雨可导致滑体蠕动或局部滑移,引起隧道不均匀受力及变形,这对隧道结构的安全非常不利。本次试验可为雨水充沛区的滑坡及隧道抗滑设计提供一定参考。 相似文献
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15.
A method is presented for incorporating the uncertainties associated with hypocentral locations in the formulation of probabilistic models of the time and space distributions of the activity of potential seismic sources, as well as of the resulting seismic hazard functions at sites in their vicinity. For this purpose, a bayesian framework of analysis is adopted, where the probabilistic models considered are assumed to have known forms and uncertain parameters, the distribution of the latter being the result of an a priori assessment and its updating through the incorporation of the direct statistical information, including the uncertainty associated with the relations between the actual hypocentral locations and the reported data. This uncertainty is incorporated in the evaluation of the likelihood function of the parameters to be estimated for a given sample of recorded locations. For the purpose of illustration, the method proposed is applied to the modelling of the seismic sources near a site close to the southern coast of Mexico. The results of two alternate algorithms for the incorporation of location uncertainties are compared with those arising from neglecting those uncertainties. One of them makes use of Monte Carlo simulation, while the other is based on a closed-form analytical integration following the introduction of some simplifying assumptions. For the particular case studied, accounting for location uncertainties gives place to significant changes in the probabilistic models of the seismic sources. Deviations of the same order of magnitude can be ascribed to differences in the mathematical and/or numerical tools used in the uncertainty analysis. The resulting variability of the seismic hazard at the site of interest is less pronounced than that affecting the estimates of activity of individual seismic sources. 相似文献
16.
S. M. Molodenskii M. S. Molodenskii T. A. Begitova 《Izvestiya Physics of the Solid Earth》2016,52(5):660-673
In the first part of the paper, a new method was developed for solving the inverse problem of coseismic and postseismic deformations in the real (imperfectly elastic, radially and horizontally heterogeneous, self-gravitating) Earth with hydrostatic initial stresses from highly accurate modern satellite data. The method is based on the decomposition of the sought parameters in the orthogonalized basis. The method was suggested for estimating the ambiguity of the solution of the inverse problem for coseismic and postseismic deformations. For obtaining this estimate, the orthogonal complement is constructed to the n-dimensional space spanned by the system of functional derivatives of the residuals in the system of n observed and model data on the coseismic and postseismic displacements at a variety of sites on the ground surface with small variations in the models. Below, we present the results of the numerical modeling of the elastic displacements of the ground surface, which were based on calculating Green’s functions of the real Earth for the plane dislocation surface and different orientations of the displacement vector as described in part I of the paper. The calculations were conducted for the model of a horizontally homogeneous but radially heterogeneous selfgravitating Earth with hydrostatic initial stresses and the mantle rheology described by the Lomnitz logarithmic creep function according to (M. Molodenskii, 2014). We compare our results with the previous numerical calculations (Okado, 1985; 1992) for the simplest model of a perfectly elastic nongravitating homogeneous Earth. It is shown that with the source depths starting from the first hundreds of kilometers and with magnitudes of about 8.0 and higher, the discrepancies significantly exceed the errors of the observations and should therefore be taken into account. We present the examples of the numerical calculations of the creep function of the crust and upper mantle for the coseismic deformations. We also demonstrate the results of estimating the ambiguity of the models of postseismic deformations in the vicinity of the source of the Great Tohoku earthquake of March 11, 2011, which were obtained by the method of orthogonalization described in the first part of the paper. 相似文献
17.
This paper is devoted to an analysis of brightness temperatures of the polar and low-latitude coronal holes on the Sun in the cm-wave range during periods of minimum solar activity. Data from observations of the polar coronal hole received by the RATAN-600 radio telescope during the solar eclipse of March 29, 2006, and low-latitude observations of coronal holes and quiet Sun received earlier with the RATAN-600 and BPR radio telescopes in the period of minimum solar activity have been used in the paper. The obtained good agreement between the brightness temperatures of cm-wave emission of the polar coronal hole above the North Pole of the Sun and of the low-latitude coronal holes against the background of the quiet Sun reveals the identity of the temperature properties of large coronal holes, irrespective of the mode of their arrangement and location on the Sun during the periods of minimum solar activity. 相似文献
18.
Andaman-Sumatra island arc: 1. Spatiotemporal manifestations and focal mechanisms of the earthquakes 总被引：1，自引：0，他引：1
The spatiotemporal manifestations of seismicity in the Andaman-Sumatra island arc are studied using the instrumental data
for 1900–2010. The data on the largest tsunamigenic earthquakes of the 18th–19th centuries were also taken into account. The
epicenters of the earthquakes are established to cluster in some areas; their possible relation to the structural features
of the island arc is considered. A distinctive feature of seismicity in the region of the Andaman Sea is the presence of compact
swarms of numerous earthquakes occurring during short intervals of time. The distribution of the earthquakes by the depth
of their hypocenters in different segments of the island arc is investigated. The focal mechanisms of the earthquakes are
analyzed using the centroid-moment-tensor (CMT) determinations over the period of 1980–2004, and the characteristic features
of their parameters in different segments of the Andaman-Sumatra island arc are formulated. The focal parameters of the earthquakes
determined by CMT and the moment-tensor-solution (MTS) are compared; the possible uncertainty in the estimates of the focal
mechanisms is assessed. The pattern of the spatiotemporal manifestations of the Andaman-Sumatra earthquakes and their focal
mechanisms are compared to the data on the Kuril-Kamchatka and the Aleutian island arcs previously studied by the authors.
The results of analyzing the long-term seismicity and focal mechanisms in the Andaman-Sumatra island arc provide a necessary
basis for the further thorough investigation of the geological conditions and source parameters of the major Sumatra earthquakes
of 2000–2010. 相似文献
19.
通风竖井对隧道内的通风换气、车辆动力效应调整以及防灾救援起到至关重要的作用，是长大型隧道的重要组成部分。由于受到周围岩土的约束，海底隧道穿岛通风竖井结构的稳定性往往优于水中自立式竖井。但在地震动作用下，受周围岩土的约束及土体变形的影响，隧道通风竖井的地震响应将与普通井筒及井筒式基础存在明显差异。基于大型有限元分析软件ABAQUS建立海底隧道穿岛通风竖井结构的数值模型，考虑周围岩土及底部隧道对竖井的约束，利用时程分析法计算竖井在垂直于隧道轴向的水平地震作用下的动力响应，得出了竖井内力及位移沿深度的分布特点，通过考虑不同类型的岩土材料得到了竖井结构动力响应随场地剪切波速的变化规律。 相似文献
20.
Daxian FANG Jueyi SUI Ronald W.THRING Hongya ZHANG 《国际泥沙研究》2006,21(2):89-100
1 INTRODUCTION In alluvial streams bed scour often occurs if the sediment load is less than the transport capacity of the flow. Two types of scour are identified, namely local scour and channel bed scour. Channel bed scour can be further classified accord… 相似文献