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1.
V. P. Antonova N. N. Volodichev S. V. Kryukov A. P. Chubenko A. L. Shchepetov 《Geomagnetism and Aeronomy》2009,49(6):761-767
The unit for detecting thermal neutrons, which makes it possible to study variations in cosmic rays of the interplanetary
and geophysical origin, has been created at the high altitude cosmic ray station (3340 m above sea level) near the Earth’s
crust fault. It has been established that variations in thermal neutrons are of the same nature as high-energy variations
registered with a neutron supermonitor in the absence of seismic activity. The flux of thermal neutrons from the Earth’s crust
during seismic activity in December 2006 has been registered for the first time. The flux value is higher than the background
level by 5–6%. The method for detecting the flux of thermal neutrons from the Earth’s crust with the simultaneous registration
of high-energy neutrons has been proposed. 相似文献
2.
The role of the gravitational potential of the lithosphere in the formation of a global stress field
The global stress field appearing in the Earth’s lithosphere under the action of forces caused by the difference of gravitational
potential is calculated. An original algorithm is proposed and the operational Earth Stresses program code is developed. The
data on the topography, thickness, and density of the Earth’s crust and the upper mantle, as well as the gravitational anomalies
and thermal conditions in the lithosphere were taken into account in the calculations. A comparison of the calculation results
and the observed data makes it possible to conclude that the action of the forces of the difference of the gravitational potential
alone is sufficient to explain the features of the first order of the stress field in the Earth’s lithosphere. 相似文献
3.
A. D. Kostyuk N. A. Sycheva S. L. Yunga L. M. Bogomolov Y. Yagi 《Izvestiya Physics of the Solid Earth》2010,46(3):230-243
For evaluating the deformations of the Earth’s crust in the Northern Tien Shan, we calculated the mode and intensity of the
seismotectonic deformations (STD) for this region. The input for these calculations were the catalog data on the focal mechanisms
of earthquakes, obtained by wave inversion of the signals recorded at the Kyrgyz seismic network (KNET) for the period 1994–2006.
In the construction of STD maps, a modern approach to the classification of seismotectonic deformations was applied. This
approach distinguishes eleven typical patterns of deformation. The areal distributions of the Lode-Nadai coefficient, as well
as of the vertical component and the aspect angle of the deformed state were obtained. At the same time, based on the GPS
measurements in the Northern Tien Shan during 1994–2006, the rates of dilatation and shear deformation of the Earth’s crust
were estimated. A comparison between the directions of strain axes derived from the GPS data and from the earthquake focal
data is carried out. 相似文献
4.
In 25 years, the presence of azimuthally varying seismic anisotropy throughout the Earth’s crust has progressed from general
denial to universal acceptance, so that many international geophysical meetings now have sessions on seismic anisotropy. Over
this period, the proceedings of the biennial series of International Workshops in Seismic Anisotropy (IWSAs) have captured
many of the notable advances in the theory, calculation, observation and interpretation of particularly shear-wave splitting
(seismic birefringence) in the Earth’s crust. Shear-wave splitting is the almost-infallible indicator of seismic anisotropy
along the ray path. This paper reviews 13 IWSA meetings (0IWSA–12IWSA) as a catalogue of 25 years of progress in seismic anisotropy.
The evidence now suggests that shear-wave splitting monitors the low-level pre-fracturing deformation of the stress-aligned
fluid-saturated microcracks pervading almost all in situ rocks in the crust. Shear-wave splitting indicates that microcracks
are so closely spaced they are critical systems with all the universality, calculability, predictability, “butterfly wing’s”
sensitivity, and deterministic chaos that that implies. This leads to a New Geophysics, where low-level deformation can be
monitored with shear-wave splitting, future behaviour calculated–predicted with the anisotropic poro-elastic model of rock
evolution, and in some circumstances even potentially controlled by feedback. We anticipate the New Geophysics will greatly
invigorate IWSA. 相似文献
5.
We derive expressions for computing the gravitational field (potential and its radial derivative) generated by an arbitrary
homogeneous or laterally varying density contrast layer with a variable depth and thickness based on methods for a spherical
harmonic analysis and synthesis of gravity field. The newly derived expressions are utilised in the gravimetric forward modelling
of major known density structures within the Earth’s crust (excluding the ocean density contrast) beneath the geoid surface.
The gravitational field quantities due to the sediments and crust components density contrasts, shown in numerical examples,
are computed using the 2 × 2 arc-deg discrete data from the global crustal model CRUST2.0. These density contrasts are defined
relative to the adopted value of the reference crustal density of 2670 kgm−3. All computations are realised globally on a 1 × 1 arc-deg geographical grid at the Earth’s surface. The maxima of the gravitational
signal due to the sediments density contrast are mainly along continental shelf regions with the largest sedimentary deposits.
The corresponding maxima due to the consolidated crust components density contrast are over areas of the largest continental
crustal thickness with variable geological structure. 相似文献
6.
V. V. Adushkin A. A. Spivak V. A. Kharlamov 《Izvestiya Physics of the Solid Earth》2012,48(2):104-116
Extraterrestrial forcing of natural environmental processes by gravitational interaction between the Sun, the Moon, and the
Earth is considered. Based on the instrumental data, the main periodical components and cycles are identified in the time
variations of some geophysical fields at the boundary between the Earth’s crust and the atmosphere. Correlation analysis shows
that the lunar-solar tides are the key factor responsible for diurnal and quasi-biweekly variations in the ground electric
field, radon emanation, water level in wells, and microseismic vibrations. The tidal influence on the various-scale movements
of the blocks of the Earth’s crust is analyzed. In the context of the vertical, lateral, and rotational motion of crustal
blocks, which is very important for the platforms, a new, precession-like type of displacements is revealed. These movements
develop as a result of the nonsynchronous tidal responses of the block and the adjacent interblock gaps or tectonic structures
whose strength and strain properties are different in different directions. 相似文献
7.
A. V. Gorbatikov A. N. Ovsyuchenko E. A. Rogozhin M. Yu. Stepanova N. V. Larin 《Seismic Instruments》2011,47(4):307-313
The Vladikavkaz Fault Zone is a regional boundary between the Alpine folded-block system of the Greater Caucasus and Pre-Caucasus
foredeep (Ossetian Depression). A complex of geological and geomorphological techniques was used for its study. The data of
recent activity of discontinuous and folded dislocations were obtained as a result. Additional application of the microseismic
sounding method allowed us to trace the behavior at depth and along the direction of the Vladikavkaz Fault Zone’s branches
known on the Earth’s surface from geological and geophysical surveys. An idea of the three-dimensional structure of this system
of tectonic faults was made up. It was shown that the structure of the upper section of the fault zone has a form of listric
foldthrust, and in the deep layers of the Earth’s crust it is represented by a well-formed contrast zone with subvertical
plunging. Expressive deformations of young sediments and a clear manifestation of the fault zone at a depth make it possible
to consider the Vladikavkaz Fault as a major seismogenerating structure. 相似文献
8.
We study the changes in the rate of seismotectonic strains in the Earth’s crust in two of the most seismically active Central
Asian areas, the Garm region in Tadjikistan and the Northern Tien Shan, which are excited by high energy pulsed electromagnetic
irradiation. It is shown that in both areas the average rates of strain release increase by a factor of 10–20. The increment
of the seismotectonic strains initiated during the entire period of electromagnetic treatment is 1.3 × 10−6–6.3 × 10−6, which is comparable with the value of crustal strains observed during the preparation of strong earthquakes and amounts
to 3–13% of the ultimate strains for rocks. Such a contribution to the process of quasi-plastic strains of the crust results
in the additional relaxation of elastic stresses by 0.4–1.67 bar, which corresponds to approximately 1–17% of the stress released
in the sources of strong earthquakes. The spatial variations in the changes of the strain rate during electromagnetic treatment
are studied, and their correlation with the level of stresses in the Earth’s crust is revealed. It is shown that the change
in the strain rate during the electromagnetic excitation can be used as the criterion for active monitoring of the stress
state of the medium for the purposes of predicting the location, time, and magnitude of strong earthquakes. 相似文献
9.
The conductivity anisotropy behaviour is described for certain environment in the Earth’s crust and the MT inversion method
for a layered symmetrically anisotropic model is presented. The inversion interpretations of the anisotropic model from the
observational data are helpful to identify the earthquake precusors as indicated by the deep conductivity anisotropic variations,
and also provide some useful information to investigate the stress states and deformation bands in the deep crust of the Earth.
This project is sponsored by the Chinese Joint Seismological Science Foundation. 相似文献
10.
S. I. Boldyrev O. P. Kolomytsev G. S. Ivanov-Kholodny A. P. Ignatyev 《Geomagnetism and Aeronomy》2009,49(8):1278-1282
The present-day models of the Earth’s upper atmosphere make it possible to construct the spatial-temporal pattern of variations
in the atmospheric parameters on the planetary scale in essence in the averaged form. The set of data on the satellite deceleration
in the atmosphere, probe measurements aboard geophysical rockets, and radiowave incoherent scatter measurements in the Earth’s
atmosphere are used to construct these standard models. The current level of the space studies makes it possible to use a
new method to study the Earth’s upper atmosphere: to study the upper atmosphere by measuring the absorption of the solar XUV
radiation by the Earth’s atmosphere during the solar disk observations. 相似文献
11.
Grigory I. Dolgikh Stanislav G. Dolgikh Sergei N. Kovalev Vladimir V. Ovcharenko Vladimir A. Chupin Vyacheslav A. Shvets Sergei V. Yakovenko 《Acta Geophysica》2007,55(4):607-618
The experimental data in the microseismic frequency range obtained using the seismo-acoustic-hydrophysical measurement complex
are analyzed. The emphasis is put on estimating the ratio between the energy of surface sea wind waves in the area of the
Japan Sea where the complex was located and the Earth’s crust microdeformations in this frequency range. The experimental
evaluate obtained allow us to estimate the energy re-distribution at the hydrosphere-lithosphere boundary. 相似文献
12.
The studies on the structure and physical properties of the Earth‘s interior done by Chinese geophysicists from 1999 to 2002 were reviewed in this paper. It includes several research areas: the structure of the Earth‘s interiors using seismic tomography, anisotropy of the upper mantle in China and its adjacent areas, quality factor Qβ for S waves, subduction zone, mantle discontinuities, physical properties of Earth‘s materials and others. The review concerns mainly the contents, the methods and the results of the studies. It can be seen that new progress in the study on the structure and physical properties of the Earth‘s interior has been made in the last 4 years in China. It is shown on three aspects: advancement made on some preexistent areas; pioneering on some new fields and new methods adopted. 相似文献
13.
This article considers the process of entry of cosmic substance into the Earth’s atmosphere and the further evolution of the
formed extraterrestrial aerosol. It is shown that meteorite-derived aerosol generated in the atmosphere may affect the Earth’s
climate in two ways: (a) particles of meteoric haze may serve as condensation nuclei in the troposphere and stratosphere;
(b) charged meteor particles residing in the mesosphere may markedly change (by a few percent) the total atmospheric resistance
and, thereby, affect the global current circuit. Changes in the global electric circuit, in turn, may influence cloud formation
processes. The obtained results argue for the fact that the meteoric dust in the Earth’s atmosphere is potentially one of
the important climate-forming agents. It is shown that the amount of interstellar dust in the Earth’s atmosphere is too small
to have a considerable affect on atmospheric processes. 相似文献
14.
Based on the time series of observational variations of the length of day (LOD) and seismic data in the world, the relations
of the decadal fluctuation and seasonal variation in the Earth’s rotation with global seismic activity are studied in this
paper. The results suggest that there are overall correlations on temporal scale and regional discrepancy on spatial scale
between global seismic activity and the Earth’s variable rotation, especially the seismic activity in the Eurasian seismic
zone (not including southeast Asia) and the Lower California-Eastern Alaska seismic zone correlating well with the Earth’s
variable rotation. According to the relations mentioned above, the observational data of the Earth’s rotation might provide
a referential basis for monitoring global seismic activity.
This project is sponsored by the National Key Basic Research Project and the National Natural Science Foundation of China.
The English version is improved by Prof. Xin-Ling QIN, Institute of Geophysics, SSB, China. 相似文献
15.
V. V. Kopeikin 《Geomagnetism and Aeronomy》2011,51(5):676-680
It has been indicated that the electric field that exists above the Earth’s surface contains information about the structure
of underground inhomogeneities. Equations have been obtained and are used to illustrate the numerical calculations of the
electric field strength along the Earth’s surface and some types of underground objects. 相似文献
16.
S. M. Korotaev M. S. Zhdanov D. A. Orekhova M. S. Kruglyakov I. L. Trofimov Yu. G. Schors V. S. Shneyer 《Izvestiya Physics of the Solid Earth》2010,46(9):759-771
The task of the magnetotelluric (MT) sounding of the heterogeneous deep section of the Arctic ocean floor on the idealized
model of gorst and graben lying on the typical oceanic, or continental Earth’s, crust is solved with the use of 3D quantitative
modeling. In both cases, the sequence is covered by a layer of seawater with a thickness of 4 km. In this work, the difference
in the MT sounding with the use of ocean-floor and surface equipment is considered. As a result, the conclusion was made that
the floor equipment has a higher resolution than the surface equipment, in spite of the fact that the observations from the
ice cover’s surface can be done more easily. 相似文献
17.
The elasto-gravitational deformation response of the Earth’s solid parts to the perturbations of the pressure and gravity
on the core-mantle boundary (CMB) and the solid inner core boundary (ICB), due to the dynamical behaviors of the fluid outer
core (FOC), is discussed. The internal load Love numbers, which are formulized in a general form in this study, are employed
to describe the Earth’s deformation. The preliminary reference Earth model (PREM) is used as an example to calculate the internal
load Love numbers on the Earth’s surface, CMB and ICB, respectively. The characteristics of the Earth’s deformation variation
with the depth and the perturbation periods on the boundaries of the FOC are also investigated. The numerical results indicate
that the internal load Love numbers decrease quickly with the increasing degree of the spherical harmonics of the displacement
and depend strongly on the perturbation frequencies, especially on the high frequencies. The results, obtained in this work,
can be used to construct the boundary conditions for the core dynamics of the long-period oscillations of the Earth’s fluid
outer core.
Foundation item: State Natural Science Foundation of China (40174022 and 49925411) and the Projects from Chinese Academy of Sciences (KZCX2-106
and KZ952-J1-411). 相似文献
18.
V. N. Pilipenko A. O. Verpakhovskaya V. I. Starostenko N. I. Pavlenkova 《Izvestiya Physics of the Solid Earth》2010,46(11):943-954
The main results of deep seismic sounding (DSS) are usually presented in the form of high-velocity models of the medium. Some
model examples and the international DOBRE profile have shown that the informativeness of the data obtained can be significantly enhanced by the construction of wave
images of the Earth’s crust, based on the migration of refracted and wide-angle reflected waves. The Donets Basin Refraction/Reflection
Experiment (DOBRE) profile crosses the Dnieper-Donets paleorift zone in the Donbas region. Along the profile, refracted waves from the basement
and the upper mantle and the reflections from the crust basement (the M boundary) are reliably traced. This wave migration has been used to construct a wave image of the structure of the Earth’s
crust. As a result, a clear seismic image of the basement surface, whose depth changes along the profile from 0 to 20 km,
was obtained. In near-slope parts of the basin, several major faults were identified that had not been identified previously
during standard kinematic data processing. It is shown that the crust-upper mantle transition zone is a clearly reflective
horizon only within the crystalline massifs; under a depression, it is represented by a lens-shaped highly-heterogeneous area.
As shown in the model examples, the images obtained using such a migration accurately reflect the structural features of the
medium, in spite of its complicated structure. 相似文献
19.
Besides generating seismic waves, which eventually dissipate, an earthquake also generates a static displacement field everywhere within the Earth. This global displacement field rearranges the Earth’s mass thereby causing the Earth’s rotation and gravitational field to change. The size of this change depends upon the magnitude, focal mechanism, and location of the earthquake. The Sumatran earthquake of December 26, 2004 is the largest earthquake to have occurred since the 1960 Chilean earthquake. Using a spherical, layered Earth model, the coseismic effect of the Sumatran earthquake upon the Earth’s length-of-day, polar motion, and low-degree harmonic coefficients of the gravitational field are computed. Using a model of the earthquake source that is composed of five subevents having a total moment-magnitude M
w
of 9.3, it is found that this earthquake should have caused the length-of-day to decrease by 6.8 microseconds, the position of the Earth’s generalized figure axis to shift 2.32 milliarcseconds towards 127° E longitude, the Earth’s oblateness J
2 to decrease by 2.37 × 10−11 and the Earth’s pear-shapedness J
3 to decrease by 0.63 × 10−11. The predicted change in the length-of-day, position of the generalized figure axis, and J
3 are probably not detectable by current measurement systems. But the predicted change in oblateness is perhaps detectable if other effects, such as those of the atmosphere, oceans, and continental water storage, can be adequately removed from the observations. 相似文献
20.
Effect of point source and heterogeneity on the propagation of SH-Waves in a viscoelastic layer over a viscoelastic half space 总被引:1,自引:1,他引:0
The present paper is concerned with the propagation of shear waves in a homogeneous viscoelastic isotropic layer lying over
a semi-infinite heterogeneous viscoelastic isotropic half-space due to point source. The inhomogeneity parameters associated
to rigidity, internal friction and density are assumed to be functions of depth. The dispersion equation of shear waves has
been obtained using Green’s function technique. The dimensionless angular frequency has been plotted against dimensionless
wave number for different values of inhomogeneity parameters. The effects of inhomogeneity have been shown in the dispersion
curves. graphical user interface (GUI) software in MATLAB has been developed to show the effect of various inhomogeneity parameters
on angular frequency. The topic can be of interest for geophysical applications in propagation of shear waves on the Earth’s
crust. 相似文献