Structure et Propriétés Physiques de l'Écorce Terrestre en Fenno-Scandinavie

1972 ◽  
Vol 9 (4) ◽  
pp. 339-352 ◽  
Author(s):  
Maurice K. Seguin
Keyword(s):  
Seismic Data ◽  
Seismic Waves ◽  
Earth’S Crust ◽  
Tectonic Activity ◽  
Seismic Events ◽  
Work Related ◽  
Global Geodynamics ◽  
Propriétés Physiques ◽  
Earth's Crust ◽  
East West

The author completely reviews previous geophysical work related to the nature and structure of the earth's crust in Fennoscandia. He explains the analytical procedure used for the seismic data and the method used to locate seismic events in Fennoscandia. Having described the method of analysis, the procedure for the calculation of the velocity of the seismic waves, and the location of seismic events which originate from Fennoscandia as well as the characteristics of the seismic waves registered, the author calculates the thickness of 3 layers which constitute the earth's crust at various localities in Fennoscandia and drafts a spatial distribution for the thickness of each of these layers. The first order variations, which agree with the relative thickness of the layers, indicate the presence of a generally east-west gradient. A general thinning of the crust was observed to the west in Fennoscandia. In view of the results obtained, the author draws conclusions relative to the tectonic activity and the global geodynamics in Fennoscandia.

scholarly journals Geodynamics of the territory of Аrmenia based on the results of comprehensive observations

2019 ◽  
Vol 1 (1) ◽  
pp. 101-109
Author(s):  
Romela Pashayan ◽  
Levon Harutyunyan ◽  
Kristina Tovmasyan
Keyword(s):  
Seismic Data ◽  
Mineral Waters ◽  
Earth’S Crust ◽  
Seismic Events ◽  
The Past ◽  
Geodynamic Processes ◽  
Earth's Crust ◽  
Main Components ◽  
Increased Activity ◽  
Vertical Deformations

The geodynamics of the earth’s crust in the territory of Armenia is given according to seismic data, deformographic measurements, hydro geodynamic observations of the groundwater level, and geochemistry of mineral waters in the central part of the region. The map of the epicenters of earthquakes over the past three years includes stressed sections (concentration of earthquake epicenters) of the earth’s crust with increased activity geodynamic processes. Based on the results of the registration of deformations of two directions, the values of areal, volumetric, and vertical deformations are calculated. Variations in the water level in hydro geodynamic wells were obtained due to seismic events; the amplitudes of the variations depend on the magnitude of the earthquake, the distance from the epicenter, and the magnitude of the calculated deformation of the earth’s crust. The main components of the chemical composition of mineral waters (CL, HCO3, SO4, Mg), gas - CO2, and Ph in comparison with seismicity and other geodynamic processes of the earth’s crust.

scholarly journals Simulation of seismic waves at the earth's crust (brittle–ductile transition) based on the Burgers model

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 1001-1010 ◽  
Author(s):  
J. M. Carcione ◽  
F. Poletto ◽  
B. Farina ◽  
A. Craglietto
Keyword(s):  
Seismic Waves ◽  
In Situ Stress ◽  
Seismic Attenuation ◽  
Earth’S Crust ◽  
S Wave ◽  
Fourier Pseudospectral Method ◽  
Stress Criterion ◽  
Brittle Ductile Transition ◽  
Earth's Crust

Abstract. The earth's crust presents two dissimilar rheological behaviors depending on the in situ stress-temperature conditions. The upper, cooler part is brittle, while deeper zones are ductile. Seismic waves may reveal the presence of the transition but a proper characterization is required. We first obtain a stress–strain relation, including the effects of shear seismic attenuation and ductility due to shear deformations and plastic flow. The anelastic behavior is based on the Burgers mechanical model to describe the effects of seismic attenuation and steady-state creep flow. The shear Lamé constant of the brittle and ductile media depends on the in situ stress and temperature through the shear viscosity, which is obtained by the Arrhenius equation and the octahedral stress criterion. The P and S wave velocities decrease as depth and temperature increase due to the geothermal gradient, an effect which is more pronounced for shear waves. We then obtain the P−S and SH equations of motion recast in the velocity-stress formulation, including memory variables to avoid the computation of time convolutions. The equations correspond to isotropic anelastic and inhomogeneous media and are solved by a direct grid method based on the Runge–Kutta time stepping technique and the Fourier pseudospectral method. The algorithm is tested with success against known analytical solutions for different shear viscosities. A realistic example illustrates the computation of surface and reverse-VSP synthetic seismograms in the presence of an abrupt brittle–ductile transition.

scholarly journals Musification of Seismic Data

2016 ◽  
Author(s):  
Ryan McGee ◽  
David Rogers
Keyword(s):  
Wave Equation ◽  
New Media ◽  
Seismic Data ◽  
Seismic Events ◽  
Digital Audio ◽  
The Public ◽  
General Wave ◽  
Musical Compositions ◽  
The Creation ◽  
Earth's Crust

Seismic events are physical vibrations induced in the earth’s crust which follow the general wave equation, making seismic data naturally conducive to audification. Simply increasing the playback rates of seismic recordings and rescaling the amplitude values to match those of digital audio samples (straight audification) can produce eerily realistic door slamming and explosion sounds. While others have produced a plethora of sucha udifications for international seismic events (i.e. earthquakes), the resulting sounds, while distinct to the trained auditory scientist, often lack enough variety to produce multiple instrumental timbres for the creation of engaging music for the public. This paper discusses approaches of sonification processing towards eventual musification of seismic data, beginning with straight audification and resulting in several musical compositions and new-media installations containing a variety of seismically derived timbres.

scholarly journals Magnetic effects due to earthquakes and underground explosions: a review

1997 ◽  
Vol 40 (2) ◽  
Author(s):  
V. V. Surkov ◽  
V. A. Pilipenko
Keyword(s):  
Magnetic Induction ◽  
Geomagnetic Field ◽  
Seismic Waves ◽  
Physical Nature ◽  
Earth’S Crust ◽  
Magnetic Effects ◽  
Tsunami Detection ◽  
Electromagnetic Effects ◽  
Earth's Crust ◽  
Theoretical Results

The physical nature of quasi-static and transient anomalies in the geomagnetic field induced by underground explosions or earthquakes is reviewed. New theoretical results obtained recently and so far little known to general circles of geophysicists are presented. The physical nature of residual magnetic and electrotelluric fields at the explosion point are considered. The seismic waves from explosions or distant earthquakes are suggested to be used as a tool for the preliminary probing of the Earth's crust sensitivity to various seismo-electromagnetic effects. The use of magnetic induction effects for tsunami detection and for crust sounding is outlined. The nature of ULF magnetic impulses related with earthquakes is discussed.

scholarly journals Transient electromagnetic radiation of the lithosphere in a seismically active region

2019 ◽  
Vol 127 ◽  
pp. 03006
Author(s):  
Yiyang Luo ◽  
Nguyen Xuan An ◽  
Vladislav Lutsenko ◽  
Vladimir Uvarov
Keyword(s):  
Electromagnetic Field ◽  
Active Region ◽  
Electromagnetic Radiation ◽  
Seismic Waves ◽  
Earth’S Crust ◽  
Schumann Resonance ◽  
Short Term ◽  
Transient Electromagnetic ◽  
Earth's Crust ◽  
High Level

To study the electromagnetic radiation of the lithosphere associated with seismic waves, we used the recordings of the natural electromagnetic radiation obtained under conditions of weak industrial noise and a high level of microseismicity in the ELF-VLF wave bands. It is shown that these data contain information about the surface waves of the Earth’s crust and are accompanied by a frequency close to the first harmonic of the Schumann resonance. The distribution of spikes over thresholds is obtained, which can be indicators of the activity in the processes of the Earth’s crust. The averaged form of the spikes for different components of the electromagnetic field is obtained. Attention is drawn to the differences in the various components of the electromagnetic field and their diurnal differences are analyzed. The possibility of using the approach to predict the short-term movement of the Earth’s crust is considered.

Fast collocation for Moho estimation from GOCE gravity data: the Iran case study

2020 ◽  
Vol 221 (1) ◽  
pp. 651-664
Author(s):  
H Heydarizadeh Shali ◽  
D Sampietro ◽  
A Safari ◽  
M Capponi ◽  
A Bahroudi
Keyword(s):  
Root Mean Square ◽  
Root Mean Square Deviation ◽  
Seismic Data ◽  
Active Faults ◽  
Earth’S Crust ◽  
Arabian Plate ◽  
Moho Depth ◽  
Mean Square ◽  
Mean Square Deviation ◽  
Earth's Crust

SUMMARY The study of the discontinuity between crust and mantle beneath Iran is still an open issue in the geophysical community due to its various tectonic features created by the collision between the Iranian and Arabian Plate. For instance in regions such as Zagros, Alborz or Makran, despite the number of studies performed, both by exploiting gravity or seismic data, the depth of the Moho and also interior structure is still highly uncertain. This is due to the complexity of the crust and to the presence of large short wavelength signals in the Moho depth. GOCE observations are capable and useful products to describe the Earth’s crust structure either at the regional or global scale. Furthermore, it is plausible to retrieve important information regarding the structure of the Earth’s crust by combining the GOCE observations with seismic data and considering additional information. In the current study, we used as observation a grid of second radial derivative of the anomalous gravitational potential computed at an altitude of 221 km by means of the space-wise approach, to study the depth of the Moho. The observations have been reduced for the gravitational effects of topography, bathymetry and sediments. The residual gravity has been inverted accordingly to a simple two-layer model. In particular, this guarantees the uniqueness of the solution of the inverse problem which has been regularized by means of a collocation approach in the frequency domain. Although results of this study show a general good agreement with seismically derived depths with a root mean square deviation of 6 km, there are some discrepancies under the Alborz zone and also Oman sea with a root mean square deviation up 10 km for the former and an average difference of 3 km for the latter. Further comparisons with the natural feature of the study area, for instance, active faults, show that the resulting Moho features can be directly associated with geophysical and tectonic blocks.

scholarly journals Local seismicity alterations in the South Yakutia mining region due to the technogenic impact on its geological environment

2018 ◽  
Vol 56 ◽  
pp. 04019
Author(s):  
Nikolay Grib ◽  
Valery Imaev ◽  
Galina Grib ◽  
Lyudmila Imaeva ◽  
Igor Kolodeznikov
Keyword(s):  
Indirect Effects ◽  
Earth’S Crust ◽  
Seismic Events ◽  
Geological Environment ◽  
The South ◽  
Near Surface ◽  
Earthquake Energy ◽  
Technogenic Impact ◽  
Earth's Crust ◽  
The Impact

Impulse loads, arising due to the high natural seismicity of the South Yakutia region, exercise both direct and indirect effects on the upper part of the Earth's crust during industrial explosions. The direct effects result from nonlinear displacements caused by the blast wave and the subsequent formation of new disturbances. The indirect effects arise due to the activation of structural elements along geological contacts, leading to the emergence of technogenic seismicity foci. The foci of induced seismicity are either confined to the blast points, or located along the tectonic structures crossing quarry fields. The technogenic impact on the geological environment transforms the independent local seismic process, since explosions trigger a chain of local seismic events. The near-surface layers of the Earth's crust become activated in the area of dynamic influence of active faults. Under the influence of explosions, both the number of seismic events and the average level of released energy alter. Impulse loads on the geological environment lead to a spatial redistribution of the foci of low-energy (K <7) earthquakes. The main form of the geodynamic development of seismogenic faults is the movement of their sides in the form of mutual “slippage”. Seismic events are manifested only when the aforementioned form of deformation is impossible or difficult to develop, in other words, when the stress-state areas of the Earth's crust develop. Therefore, the shaking impact of blasts can be considered as a factor contributing to the predominance of aseismic forms of fault motion in the form of smooth slippage of their sides. In conclusion, the impact of industrial blasts can not only activate faults around the mining area, but also have an unloading effect on the foci of seismic hazard forming in the interior, i.e. the redistribution of earthquake energy in terms of reducing earthquake energy class.

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