共查询到20条相似文献，搜索用时 15 毫秒
1.
M. S. Molodenskii S. M. Molodenskii T. A. Begitova A. L. Zagoskin 《Izvestiya Physics of the Solid Earth》2017,53(3):458-460
The time variations in the tidal response of the medium in 2011–2015 according to the measurements at the global seismographic network (GSN) in Kamchatka are considered. Based on the data from the horizontal pendulums recording the eastward tilts at the station, it is established that there was a linear growth in the tidal tilt amplitudes up to May 24, 2013 due to the changes in the elastic moduli caused by tectonic stress accumulation. The growth phase was followed by the decline in the tidal tilt amplitudes induced by the release of stresses after the Sea-of-Okhotsk earthquake. 相似文献
2.
M. S. Molodenskiy D. S. Molodenskiy T. A. Begitova 《Izvestiya Physics of the Solid Earth》2016,52(2):210-217
The idea of forecasting the earthquakes by continuous monitoring the time variations of tidal responses was suggested by E. Nishimura in 1950. However, the implementation of this idea has only become possible with the deployment of the GSN and F-net global seismic networks. Below, we present the new method for identifying the time variations of tidal response of the medium in seismically active regions using the data from these networks. We show that our approach significantly increases the sensitivity and time resolution of the standard methods of moving spectral analysis. The analysis of the data from the horizontal pendulums which record the northward tilts demonstrates the slow growth of the tidal tilts during six years before the earthquake, which is followed by the instantaneous drop of the amplitudes at the moment of the earthquake. During four years after this drop, the tidal amplitudes remained at a noticeably lower level than their average preearthquake values. These changes in the tidal amplitudes indicate the nonlinear response of the medium in the presence of large tectonic 相似文献
3.
The possibility of determining local horizontal inhomogeneities of the shear and bulk moduli from data on amplitudes and phases of tidal tilts and strains is considered. Simple analytical formulas determining the sought effects are derived by the perturbation method, and their numerical estimates are determined for the simplest 2-D models. It is shown that relative variations in the shear and bulk moduli affect not only the amplitudes and phases of variations in tidal parameters but also the shape of curves of tidal amplitude anomalies versus the horizontal coordinate. Given adequate spatial resolution, this can significantly facilitate the elastic moduli inversion from tidal data. 相似文献
4.
Estimation of the size of earthquake preparation zones 总被引：8，自引：0，他引：8
During the earthquake preparation a zone of cracked rocks is formed in the region of a future earthquake focal zone under the influence of tectonic stresses. In the study of the surrounding medium this region may be considered as a solid inclusion with altered moduli. The inclusion appearance causes a redistribution of the stresses accompanied by corresponding deformations. This paper deals with the study of deformations at the Earth's surface, resulting from the appearance of a soft inclusion. The Appendix contains an approximate solution of the problem for a soft elastic inclusion in an elastic half-space. It is assumed that the moduli of the inclusion differ slightly from those of the surrounding medium (by no more than 30%). The solution permits us to calculate the deformations at the Earth's surface for the inclusion with an arbitrary heterogeneity and anisotropy. The problem is solved by the small perturbation method. The calculation is made for a special case of a homogeneous isotropic inclusion where only the shear modulus decreases. The shear stresses act at infinity. The equations are deduced for the estimation of deformations and tilts at the Earth's surface as a function of the magnitude of the preparing earthquake and the distance from the epicentre. Comparison has shown a satisfactory agreement between the theoretical and field results. Let us assume that the zone of effective manifestation of the precursor deformations is a circle with the centre in the epicentre of the preparing earthquake. The radius of this circle called ‘strain radius’ may be calculated from the equation $$\rho = 10^{0.43M} km,$$ where M is the magnitude. It was shown that the precursors of other physical nature fall into this circle. 相似文献
5.
Prof. R. Tomaschek Ph. D. 《Pure and Applied Geophysics》1953,25(1):17-25
Summary A typical disturbance observed in the records of tilt measurements performed with horizontal pendulums in a mine at a depth of 145 m below surface, under very constant temperature conditions, has been analysed as to its correlation with the barometric pressure distribution. It is shown that the observed load tilts are not due to elastic deformations of the Earth's crust, but may be ascribed to movements of tectonic blocks of large extension. 相似文献
6.
The idea of predicting earthquakes by continuously monitoring temporal variations in the tidal response of the medium was suggested by Beaumont and Berger in 1974. However, it became possible to implement the idea only recently. This possibility has arisen due to the deployment of Global Seismic Network (GSN), which collects the data on tidal tilts and gravity in the epicenters of strong earthquakes before and after the strongest events. In this paper, we present the results of model analytical and numerical calculations of the elastic displacements of the Earth’s surface caused by the earthquakes and their preparatory processes. The analytical calculations are limited to the model of a uniform elastic halfspace; the numerical calculations, in addition to this model, also cover the models with radially heterogeneous distributions of elastic moduli in the crust and in the upper mantle, which are determined by the PREM model. We describe the results of modeling temporal variations in the tidal response of the medium in the vicinity of the source of a catastrophic earthquake. The model of seismic source is specified by the length and the orientations of the fault plane and by the value of the discontinuity in the tangential component of the displacement vector on the opposite sides of the fault. The model is based on the GPS data on the horizontal and vertical displacements of the Earth’s surface. We suggest the method for determining temporal changes in the tidal response of the medium in the seismically active regions. This method improves the sensitivity and time resolution of the standard techniques of sliding-window analysis by more than an order of magnitude. The comparative analysis of temporal variations in the tidal response of the medium in the zones of the magnitude 9 earthquake in Japan (March 9, 2011) illustrates the described approach.
相似文献7.
The idea of predicting earthquakes by continuously monitoring temporal variations in the tidal response of the medium was suggested by Beaumont and Berger in 1974. However, it became possible to implement the idea only recently. This possibility has arisen due to the deployment of Global Seismic Network (GSN), which collects the data on tidal tilts and gravity in the epicenters of strong earthquakes before and after the strongest events. In this paper, we present the results of model analytical and numerical calculations of the elastic displacements of the Earth??s surface caused by the earthquakes and their preparatory processes. The analytical calculations are limited to the model of a uniform elastic halfspace; the numerical calculations, in addition to this model, also cover the models with radially heterogeneous distributions of elastic moduli in the crust and in the upper mantle, which are determined by the PREM model. We describe the results of modeling temporal variations in the tidal response of the medium in the vicinity of the source of a catastrophic earthquake. The model of seismic source is specified by the length and the orientations of the fault plane and by the value of the discontinuity in the tangential component of the displacement vector on the opposite sides of the fault. The model is based on the GPS data on the horizontal and vertical displacements of the Earth??s surface. We suggest the method for determining temporal changes in the tidal response of the medium in the seismically active regions. This method improves the sensitivity and time resolution of the standard techniques of sliding-window analysis by more than an order of magnitude. The comparative analysis of temporal variations in the tidal response of the medium in the zones of the magnitude 9 earthquake in Japan (March 9, 2011) illustrates the described approach. 相似文献
8.
ChaoDi Xie XingLin Lei XiaoPing Wu Hong Fu ZiYao Xiong XiongLin Hu Sha Li 《中国科学:地球科学(英文版)》2016,59(2):397-407
Based on calculations of the tidal Coulomb failure stress and investigations of the correlation between the Earth tide and the Ning’er earthquake sequence, the processes of fault nucleation and failure were simulated. In these simulations we consider the influence of tidal stresses using the rate- and state-dependent friction laws. Furthermore, the effects on tidal triggering due to the stress amplitude and periodic oscillation properties were investigated, and the triggering effects between the tidal normal and tidal shear stresses were compared. The results showed that the Ning’er earthquake sequence was a physical consequence of tidal effects. A transition period T0 exists between the nucleation and failure processes of a seismic fault. When the period T of stress is equal to or becomes larger than T0, the fault response becomes dependent on the periodic features of the loading stress; however, for T < T0, the response of the fault is nearly independent of the period. Both the tidal normal and tidal shear stresses have similar effect in the nucleation and failure processes; the clock changes generally increase with the maximum amplitudes of the tidal stresses. Tidal normal and tidal shear stresses with positive amplitudes mainly induce earthquake triggering; however, the triggering effects induced by negative tidal stresses are smaller and faults are not sensitive to negative tidal stresses. Our results primarily reveal the physical mechanisms of tidal stress triggering. 相似文献
9.
根据三分量强震动传感器水平摆和竖向摆对倾斜的动力响应差异,利用谱比法计算出汶川MS8.0地震中近断层强震动的断层法线方向和平行方向的同震地面倾斜. 结果表明, 本次地震中强震动观测台处地面倾斜一般小于1deg;,影响频段主要在0.1 Hz以下,发生较大倾斜的台站主要在距地表破裂迹线30 km以内,在100 km之外或水平向加速度幅值均方根在200 cm/s2以下时很少发生0.01deg;以上的同震地面倾斜．总体上看,上盘区域的倾斜值普遍小于下盘区域,法线方向倾斜值一般大于平行线方向倾斜值．位于前山断裂与中央断裂之间区域的绵竹清平台谱比较低但平缓且频带较宽,可能反应了该区域的运动特殊性,而汶川卧龙台则显示了上盘边缘区域地面倾斜较大．逆冲段与走滑段台站倾斜对比显示,地面倾斜可能受局部场地条件影响较大． 相似文献
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11.
2011年3月11日, 一个 MW9.1地震袭击了日本本州地区, 为了分析这次地震前后主震破裂区内应力时空变化, 我们选取1996年1月~2016年6月期间发生在破裂区内的563个5.0≤MS≤6.9地震, 研究了视应力随时间的变化和空间分布。 日本MW9.1地震前从2002年中起视应力开始呈趋势性上升变化, 到2009年初以0.18 MPa/a的速率从0.6 MPa上升到1.76 MPa, 相差约3倍, 直到地震发生前夕一直保持在1.5 MPa之上。 地震发生之后, 直到2016年6月在破裂区内视应力呈缓慢下降变化, 但仍保持在1.5 MPa之上较高水平。 视应力在地面上和断层面上的分布显示, 1996—2005年间破裂区仅存在个别视应力高值, 从2006年到2011年2月, 破裂区大面积出现视应力高值。 在日本MW9.1地震发生之后的近3个月内, 破裂区视应力整体处于高值水平, 之后在较高的水平上缓慢减弱。 视应力是地震断层面上平均应力的下限, 视应力的高低在一定程度上反映的是震源断层面上平均应力的高低。 在日本MW9.1地震前, 发生在破裂区内的地震, 其断层面上的平均应力经历了大约8.5年的趋势上升变化过程。 这次大地震前破裂区所在的地壳应力逐渐增加, 最后导致断层面错动发生日本MW9.1地震。 相似文献
12.
V. Yu. Timofeev D. G. Ardyukov E. V. Boiko A. V. Timofeev A. V. Yaroshevich P. Yu. Gornov 《Izvestiya Physics of the Solid Earth》2012,48(7-8):640-652
Variations in the water level in boreholes emerge in response to tidal, baric, and tectonic forcing. We analyze the data on atmospheric pressure and water level recorded in the boreholes located in the mid-latitude Eurasia (45°?C55°N) from Western Europe (Belgium, Uccle), Siberia (coastal area of Lake Baikal, Talaya River) to Far Eastern Russia (the Bychikha borehole near Khabarovsk and the boreholes on the Kamchatka Peninsula and Kurils). The response of the water level in a borehole to periodic tidal and baric impacts is investigated. In this case, water level variations reflect areal (lateral) and vertical deformations, which allows estimating the elastic moduli and porosity of the confined aquifer in a static model. Measurements in the boreholes drilled in the fractured solid rock enable determining the geometric parameters of the fractures. The possibility to apply the method for evaluating tectonic deformations is discussed. Application of tidal coefficients of boreholes for determining the coseismic deformation is demonstrated by the example of the Kultuk earthquake (Lake Baikal, August 27, 2008, M = 6.3). 相似文献
13.
根据已发布震源机制解目录（哈佛大学CMT）,将青藏高原东部及邻区划分为5个构造应力场分区,并对各分区的地震逐个计算其发震断层面上的固体潮汐正应力、剪应力、库仑破裂应力及相位角,分析潮汐应力分量对不同类型发震断层的作用效果及其随深度变化特征.基于库仑破裂应力判断准则,研究潮汐应力对各种类型地震的触发作用;基于Schuster检验方法,统计分析潮汐应力对各个震级档、不同构造类型地震的影响.综合运用上述两种分析方法,探讨潮汐应力对不同震级地震以及处于不同构造块体、发震断层、震源深度地震的触发机制.结果表明,潮汐应力对印度块体和拉萨块体的正断和逆断型地震,滇缅泰块体、印支块体和松潘-甘孜块体的走滑和斜滑型地震,川滇菱形块体的斜滑型地震均存在不同程度的触发效应,且触发效应的强弱依赖于震源深度、震级大小、发震断层类型及其所处区域构造应力场. 相似文献
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15.
S. M. Molodenskii M. S. Molodenskii T. A. Begitova 《Izvestiya Physics of the Solid Earth》2016,52(5):648-659
Constructing detailed models for postseismic and coseismic deformations of the Earth’s surface has become particularly important because of the recently established possibility to continuously monitor the tectonic stresses in the source zones based on the data on the time variations in the tidal tilt amplitudes. Below, a new method is suggested for solving the inverse problem about the coseismic and postseismic deformations in the real non-ideally elastic, radially and horizontally heterogeneous, self-gravitating Earth with a hydrostatic distribution of the initial stresses from the satellite data on the ground surface displacements. The solution of this problem is based on decomposing the parameters determining the geometry of the fault surface and the distribution of the dislocation vector on this surface and elastic modules in the source in the orthogonal bases. The suggested approach includes four steps: 1. Calculating (by the perturbation method) the variations in Green’s function for the radial and tangential ground surface displacements with small 3D variations in the mechanical parameters and geometry of the source area (i.e., calculating the functional derivatives of the three components of Green’s function on the surface from the distributions of the elastic moduli and creep function within the volume of the source area and Burgers’ vector on the surface of the dislocations); 2. Successive orthogonalization of the functional derivatives; 3. Passing from the decompositions of the residuals between the observed and modeled surface displacements in the system of nonorthogonalized functional derivatives to their decomposition in the system of orthogonalized derivatives; finding the corrections to the distributions of the sought parameters from the coefficients of their decompositions in the orthogonalized basis; and 4. Analyzing the ambiguity of the inverse problem solution by constructing the orthogonal complement to the obtained basis. The described approach has the following advantages over the method of steepest descent which was used in our previous works: 1. Application of the perturbation method significantly reduces the volume of the computations in the real problems of coseismic and postseismic deformations (by three to four orders of magnitude when the data from a few dozens of observation points are used); 2. In contrast to the method of steepest descent, the suggested method always provides stable results. This means that adding the new satellite data does not alter the previously calculated coefficients in the low-order harmonics of the distributions of the sought parameters in the orthogonalized basis; this only changes the coefficients of the increasingly higher harmonics which determine the smallscale details in the sought distributions. 3. In contrast to the method of steepest descent, the suggested method is not only capable of constructing stable partial solutions of the inverse problem but also estimating the ambiguity of these solutions. The ambiguity is represented in terms of the superposition of the known functions contained in the orthogonal complement and, hence, with the growth of the amount of the analyzed data it is determined by the linear combination of the increasingly higher harmonics. In the second part of the paper, we present the results of the model numerical computations of Green’s function for the elastic displacements of the ground surface, which correspond to the case of the arbitrary geometry of the dislocation surface and arbitrary orientation of the dislocation vector for the real model of the radially heterogeneous gravitating Earth with the hydrostatic distribution of the initial stresses. The numerical calculations of the creep function in the upper mantle for the coseismic deformations and the ambiguity of the models of postseismic deformations in the vicinity of the source of the Great Tohoku earthquake (Japan) of March 11, 2011 are illustrated by the examples. 相似文献
16.
Olga V. Pavlenko 《Journal of Seismology》2016,20(3):803-826
To understand physical mechanisms of generation of abnormally high peak ground acceleration (PGA; >1g) during the Tohoku earthquake, models of nonlinear soil behavior in the strong motion were constructed for 27 KiK-net stations located in the near-fault zones to the south of FKSH17. The method of data processing used was developed by Pavlenko and Irikura, Pure Appl Geophys 160:2365–2379, 2003 and previously applied for studying soil behavior at vertical array sites during the 1995 Kobe (М w ?=?6.8) and 2000 Tottori (М w ?=?6.7) earthquakes. During the Tohoku earthquake, we did not observe a widespread nonlinearity of soft soils and reduction at the beginning of strong motion and recovery at the end of strong motion of shear moduli in soil layers, as usually observed during strong earthquakes. Manifestations of soil nonlinearity and reduction of shear moduli during strong motion were observed at sites located close to the source, in coastal areas. At remote sites, where abnormally high PGAs were recorded, shear moduli in soil layers increased and reached their maxima at the moments of the highest intensity of the strong motion, indicating soil hardening. Then, shear moduli reduced with decreasing the intensity of the strong motion. At soft-soil sites, the reduction of shear moduli was accompanied by a step-like decrease of the predominant frequencies of motion. Evidently, the observed soil hardening at the moments of the highest intensity of the strong motion contributed to the occurrence of abnormally high PGA, recorded during the Tohoku earthquake. 相似文献
17.
华北地区中东部涵盖北京、天津以及即将建设的雄安新区等大型城市,区内发育了张渤地震带等多条大型活动断裂,地震活动性较强,历史上发生过多次6级以上地震.本文利用Fan小波的布格重力异常一致性方法研究该区的岩石圈有效弹性厚度和均衡调整初始加载比分布,同时基于均衡调整方法计算该区垂向构造应力分布,并将以上结果与历史地震活动进行统计分析.岩石圈挠曲分析表明,华北地区中东部的岩石圈有效弹性厚度为10~65 km,分布特征为自东南向西北逐渐减小.均衡调整初始加载比为0.5~0.8,表明现今的岩石圈挠曲状态主要由莫霍面加载形成.该区地壳承载的垂向构造应力约为-20~20 MPa,中西部地区垂向构造应力向上,东北和西南地区向下.统计分析结果显示,华北地区中东部的地震活动性随着岩石圈有效弹性厚度和均衡调整初始加载比的增加而减弱,垂向构造应力零值区域地震活动性较弱.雄安新区的岩石圈有效弹性厚度大约为15 km,均衡调整初始加载比为0.5~0.6,垂向构造应力为15~20 MPa,岩石圈参数对应的地震活动性较强,相关结果对于新区建设具有一定参考价值. 相似文献
18.
对印尼地区3574次M≥5.0地震震源断层面上的海潮负荷应力进行计算,研究了地震断层上的负荷应力随深度变化以及随断层倾角和走向的变化特征.结果表明,地震断层上的负荷正应力大于负荷切应力.逆断层上的负荷应力最大,其它依次为斜滑断层、正断层和走滑断层.倾角范围在0°—50°的断层上的负荷正应力随倾角增大有减小趋势,负荷切应力在30°—50°倾角范围的断层上较大.负荷应力随断层走向的趋势性变化不明显.不同类型断层上的负荷正应力和切应力在震源深度15km处均达到最大,之后随深度增加而减小.当震源深度小于40km时,断层面上的海潮负荷应力的量级与固体潮应力相当.因此指出,在潮汐应力对地震影响的研究中,对震源深度小于40km的海洋和沿海地震,除固体潮汐应力外还需要考虑海潮负荷应力的影响. 相似文献
19.
区域构造应力场对于研究地震成因、地震预报和地球动力学都具有重要的意义。本文根据华北的主要发震构造、大地震时的地面破裂和地震断层、震源机制、断层弹性回跳模式以及潮汐力对地震的触发关系等方面的资料,综合论述了华北块断构造区的现代引张应力场。最后探讨了太平洋板块和印度板块向亚洲大陆俯冲对华北引张应力场的影响。指出深部作用对华北引张应力场的实际意义 相似文献
20.
Introduction Analyzing tectonic stress field based on focal mechanism data is an important way to the study tectonic evolvement of lithosphere and associated dynamic process. Such studies growrapidly in China and abroad (Zoback, 1992; Plenefisch, Bonjer, 1997; XU, 1985; CUI, XIE, 1999). At present most of the studies focus on the inversion of focal mechanism data for the direction and relative magnitude of stress tensor, and few on absolute stress. Using focal mechanism and fault scratch,… 相似文献