Seismic Analysis

2021 ◽  
pp. 216-239
Keyword(s):  
Seismic Analysis ◽  
Earth’S Crust ◽  
Earth Structure ◽  
Remote Areas ◽  
The Earth ◽  
The World ◽  
Earth's Crust ◽  
Sudden Motion

An earthquake is caused by sudden motion of the earth's crust. Every year, tens of thousands of earthquakes of all sizes occur all over the world. Some cause tiny or major tremors, others occur in remote areas where no one lives. This chapter allow readers to find out more about the earth structure as well as earthquake nature. Therefore, to detail the definition and construction of a spectrum, a presentation of earthquake analysis is given. In order to become familiar with this analysis, two applications are presented at the end of the chapter with a detailed solution.

Sound Off!: Placement Tests: The Shaky Bridge Connecting School and College Mathematics

2006 ◽  
Vol 100 (3) ◽  
pp. 174-178
Author(s):  
Sheldon P. Gordon
Keyword(s):  
The Other ◽  
Earth’S Crust ◽  
Placement Tests ◽  
College Mathematics ◽  
News Reports ◽  
The Earth ◽  
The World ◽  
Fault Lines ◽  
Earth's Crust

The earth's crust is composed of a series of large plates floating on underlying molten magma. These plates are constantly shifting, and as they bump into one another, one plate often rides up on top of the other near its edges. The interfaces between plates form fault lines in the earth, and the resultant pressures that build up along the interfaces eventually release to form earthquakes, as we are too often reminded in vivid news reports from around the world.

scholarly journals INQUIRY INTO VERTICAL MOVEMENTS OF THE EARTH‘S CRUST BASED ON SAMPLES FROM EASTERN LITHUANIA

2014 ◽  
Vol 40 (2) ◽  
pp. 58-67
Author(s):  
Ruta Puziene ◽  
Asta Anikeniene ◽  
Gitana Karsokiene
Keyword(s):  
Regression Models ◽  
Earth’S Crust ◽  
Movement Velocity ◽  
Correlation Matrices ◽  
Vertical Movements ◽  
Statistical Correlations ◽  
Horizontal Gradients ◽  
The Earth ◽  
Earth's Crust ◽  
Made In

In the research of vertical movements of the earth’s crust, examination of statistical correlations between the measured vertical movements of the earth’s crust and territorial geo-indexes is accomplished with the help of mathematical statistical analysis. Availability of the precise repeated levelling measuring data coupled with the preferred research methodology offer a chance to determine and predict recent vertical movements of the earth’s crust. For the inquiry into recent vertical movements of the earth’s crust, a Lithuanian class I vertical network levelling polygon was used. Drawing on measurements made in the polygon, vertical velocities of earth’s crust movements were calculated along the following levelling lines. For determining the relations shared by vertical movements of the earth’s crust and territorial geo-parameters, the following territory-defining parameters are accepted. Examination of the special qualities of relations shared by vertical movements of the earth’s crust and geo-parameters in the territory under research contributed to the computation of correlation matrices. Regression models are worked out taking into consideration only particular territory-defining geo-parameters, i.e. only those parameters which exhibit the following correlation coefficient value of the vertical earth’s crust movement velocity: r ≥ 0.50. A forecast of the velocities pertaining to vertical movements of the earth’s crust in the territory under examination was made with the application of regression models. Further in the process of this research, a map was compiled specifying the velocities of vertical movements of the earth’s crust in the territory. In the eastern part of this territory, the earth’s crust rises at a rate of up to 3 mm/year; while in the western part of it, the earth crust lowers at a rate of up to –1.5 mm/year. In order to pinpoint territories characterised by temperate and regular rising/lowering or intensive rising/lowering, a map of horizontal gradients of recent vertical earth crust movements in the territory enclosed by levelling polygon was compiled.

scholarly journals Improving of electrical channels for magnetotelluric sounding instrumentation

2015 ◽  
Vol 4 (2) ◽  
pp. 149-154 ◽  
Author(s):  
A. M. Prystai ◽  
V. O. Pronenko
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Deep Structure ◽  
Experimental Tests ◽  
Magnetotelluric Sounding ◽  
Earth’S Crust ◽  
Geomagnetic Variations ◽  
The Earth ◽  
Wide Range ◽  
Earth's Crust

Abstract. The study of the deep structure of the Earth's crust is of great interest for both applied (e.g. mineral exploration) and scientific research. For this the electromagnetic (EM) studies which enable one to construct the distribution of electrical conductivity in the Earth's crust are of great use. The most common method of EM exploration is magnetotelluric sounding (MT). This passive method of research uses a wide range of natural geomagnetic variations as a powerful source of electromagnetic induction in the Earth, producing telluric current variations there. It includes the measurements of variations of natural electric and magnetic fields in orthogonal directions at the surface of the Earth. By this, the measurements of electric fields are much more complicated metrological processes, and, namely, they limit the precision of MT prospecting. This is especially complicated at deep sounding when measurements of long periods are of interest. The increase in the accuracy of the electric field measurement can significantly improve the quality of MT data. Because of this, the development of a new version of an instrument for the measurements of electric fields at MT – both electric field sensors and the electrometer – with higher levels relative to the known instrument parameter level – was initiated. The paper deals with the peculiarities of this development and the results of experimental tests of the new sensors and electrometers included as a unit in the long-period magnetotelluric station LEMI-420 are given.

III.—The Fissure Theory of Volcanoes

1910 ◽  
Vol 7 (9) ◽  
pp. 392-394
Author(s):  
E. H. L. Schwarz
Keyword(s):  
Close Relation ◽  
Earth’S Crust ◽  
The World ◽  
Vertical Fault ◽  
Central Crater ◽  
Earth's Crust ◽  
The Many ◽  
Escape Vent

Dr. Hans Beck has adduced an example of a volcano which, according to him, has been formed independently of a fissure. The volcano pierces the centre of a faulted block, the Herdubreid, in Iceland, and on the vertical fault-faces there is no sign of any fissure. The example is probably unique in the world, and seems at first sight to negative the hypothesis that the escape of gases which tear through the earth's crust and form the chimneys of volcanoes is in the first place initiated by a fracture; on closer examination, however, the fact that the volcano stands in close relation to the faults which bound the horst, and the many cases which are known to occur where a fracture in the earth's crust may be healed at the surface so that the rocks about the fracture are subsequently more resistant than before, seem to point to the Herdubreid volcano being a normal fissure-formed volcano, only that it stands in the same relation to the fracture as a parasitic cone stands to the central crater. In other words, the chimney is an escape vent leading below the surface to one of the bounding faults of the horst.

Metamorphic Rocks

2018 ◽  
Author(s):  
Alex Maltman
Keyword(s):  
Metamorphic Rock ◽  
Central Area ◽  
Tectonic Stress ◽  
Earth’S Crust ◽  
Metamorphic Rocks ◽  
Tectonic Plates ◽  
The Earth ◽  
Two Factors ◽  
Earth's Crust ◽  
Increased Pressure

We come now to the metamorphic rocks, the result of modifications to already existing rock. I’m well aware that this can all seem a bit mysterious. After all, no one has ever seen the changes take place; no one has ever witnessed a metamorphic rock form—the processes are imperceptibly slow, and they happen deep in the Earth’s crust, way out of sight. Why should these changes happen? Well, they are primarily driven by increases in pressure and temperature, so we begin with a look at these two factors. There are sites in the Earth’s crust where material becomes progressively buried. It happens, for example, where a tectonic plate is driving underneath another one, taking rocks ever deeper as it descends. It can happen in the central area of a plate that is stretching and sagging, allowing thick accumulations of sediment. It’s pretty self-evident that as buried material gets deeper, because of the growing weight of rocks above bearing down due to gravity, it becomes subjected to increasing burial pressure. Less intuitive, though, is the fact that this pressure acts on a volume of rock equally in all directions. Imagine a small volume of rock at depth. It’s bearing the weight of the rocks above it, and so it responds by trying to move downward and to spread out laterally. Of course, it can’t because it’s constrained all around by other volumes of rock that are trying to do exactly the same thing. And so the downward gravity is translated into an all-around pressure. It’s the same effect as diving down to the bottom of a swimming pool. You feel the increased pressure owing to the weight of water above, but you feel it equally in all directions. All-round pressure like this can cause things to change in volume, through changing their density, but it can’t change their shape. However, there can be another kind of pressure as well, and this does have direction, and it can cause change of shape. In the Earth, we call it tectonic stress. It comes about through heat-driven motions in the Earth, including the movement of tectonic plates.

scholarly journals Critically Stressed Areas of Earth’s Crust as Medium for Man-caused Hazards

2018 ◽  
Vol 56 ◽  
pp. 02007 ◽  
Author(s):  
Andrian Batugin
Keyword(s):  
Critical Stress ◽  
Earth’S Crust ◽  
Mining Operations ◽  
Induced Earthquake ◽  
The Earth ◽  
Stress Zone ◽  
Mining Works ◽  
Earth's Crust ◽  
Rock Strata ◽  
Insight Into

Despite advances in rockburst studies, suddenness of major geodynamic events is reported in a number of cases. Phenomenological tectonophysical model is suggested to explain some geodynamics phenomena. Prof. Petukhov I.M. suggested a concept: the Earth crust's critical stress condition is developed due to horizontal compressive forces and entrains rock strata from the sub-surface to a certain depth. The conditions that induced earthquake in 2013 at Bachat coal field in south west Kuzbass are considered in terms of critical stress developed in the top layer of the Earth crust. Estimates show that the size of the critical stress zone, produced presumably by interaction of huge (over 100 km) crustal blocks is at least 10km. Whereas critical stress zone is located in the top part of Earth's crust, mining operations in the pit including blast operations was making a direct impact on this area. Shallow occurrence of critical stress area and its size can provide insight into why mining works brought about induced earthquake with hypocenter at the depth of several kilometers. The conclusion has been made that regional areas of critical stress within rock massif developed as a result of crustal blocks interaction create hazard medium for mining.

scholarly journals Accelerated non-linear destruction of the earth's crust

2001 ◽  
Vol 6 (4) ◽  
pp. 281-290
Author(s):  
E. V. Artyushkov
Keyword(s):  
Lower Crust ◽  
Sedimentary Basins ◽  
Earth’S Crust ◽  
Mountain Ranges ◽  
Crustal Rocks ◽  
The Earth ◽  
Lithospheric Plates ◽  
Temperature And Pressure ◽  
Earth's Crust ◽  
Major Hydrocarbon

The upper part of the Earth—the lithospheric layer,∼100 km thick, is rigid. Segments of this spherical shell–lithospheric plates are drifting over a ductile asthenosphere. On the continents, the lithosphere includes the Earth's crust,∼40 km thick, which is underlain by peridotitic rocks of the mantle. In most areas, at depths∼20–40 km the continental crust is composed of basalts with density∼2900kg m−3. At temperature and pressure typical for this depth, basalts are metastable and should transform into another assemblage of minerals which corresponds to garnet granulites and eclogites with higher densities 3300–3600 kgm−3. The rate of this transformation is extremely low in dry rocks, and the associated contraction of basalts evolves during the time≥108a. To restore the Archimede's equilibrium, the crust subsides with a formation of sedimentary basins, up to 10–15 km deep.Volumes of hot mantle with a water-containing fluid emerge sometimes from a deep mantle to the base of the lithosphere. Fluids infiltrate into the crust through the mantle part of the lithosphere. They catalyze the reaction in the lower crust which results in rock contraction with a formation of deep water basins at the surface during∼106a. The major hydrocarbon basins of the world were formed in this way. Infiltration of fluids strongly reduces the viscosity of the lithosphere, which is evidenced by narrow-wavelength deformations of this layer. At times of softening of the mantle part of the lithosphere, it becomes convectively replaced by a hotter and lighter asthenosphere. This process has resulted in the formation of many mountain ranges and high plateaus during the last several millions of years. Softening of the whole lithospheric layer which is rigid under normal conditions allows its strong compressive and tensile deformations. At the epochs of compression, a large portion of dense eclogites that were formed from basalts in the lower crust sink deeply into the mantle. In some cases they carry down lighter blocks of granites and sedimentary rocks of the upper crust which delaminate from eclogitic blocks and emerge back to the crust. Such blocks of upper crustal rocks include diamonds and other minerals which were formed at a depth of 100–150 km.

I.—Contributions to the Study of Volcanos.—Second Series

1876 ◽  
Vol 3 (8) ◽  
pp. 337-345 ◽  
Author(s):  
John W. Judd
Keyword(s):  
Earth’S Crust ◽  
Abnormal Development ◽  
Preliminary Stage ◽  
Mountain Ranges ◽  
Sedimentary Deposits ◽  
The Earth ◽  
Mountain System ◽  
Earth's Crust ◽  
Green Mountains

The study of the great mountain ranges of America by Rogers, Hall, Dana, Le Conte, Hunt, and other geologists, has now thrown much new light on the earth-movements which precede and accompany the formation of mountain chains. As the result of these researches, it appears certain that the preliminary stage in the formation of every mountain system has consisted in a long-continued depression of the area which is afterwards to become its site; and, in consequence of this prolonged subsidence, the accumulation of an enormous thickness of stratified rocks, within the great trough so formed, has taken place. Of this character, as is now well known, have been the earlier manifestations of the subterranean forces that were concerned in the formation of the Appalachians, Green Mountains, and other American ranges; the districts in which they are situated were subjected to long-continued depression, which permitted of an abnormal development of all the members of the sedimentary deposits formed during this initiatory period; and it was by the folding, metamorphism and crushing together of this abnormally thickened portion of the earth's crust that the indurated and elevated masses have been formed which denudation has sculptured into the existing mountain chains.

scholarly journals A New Model to Explain the Alignment of Certain Ancient Sites

2020 ◽  
Vol 34 (2) ◽  
pp. 209-232
Author(s):  
Mark Carlotto
Keyword(s):  
Climate Change ◽  
North Pole ◽  
Earth’S Crust ◽  
Upper Egypt ◽  
New Model ◽  
The Past ◽  
The North ◽  
The World ◽  
Global Patterns ◽  
Earth's Crust

In a previous study of over two hundred ancient sites, the alignments of almost half of the sites could not be explained. These sites are distributed throughout the world and include the majority of Mesoamerican pyramids and temples that are misaligned with respect to true north, megalithic structures at several sites in Peru’s Sacred Valley, some pyramids in Lower Egypt, and numerous temples in Upper Egypt. A new model is proposed to account for the alignment of certain unexplained sites based on an application of Charles Hapgood’s hypothesis that global patterns of climate change over the past 100,000 years could be the result of displacements of the Earth’s crust and corresponding shifts of the geographic poles. It is shown that over 80% of the unexplained sites reference four locations within 30° of the North Pole that are correlated with Hapgood’s hypothesized pole locations. The alignments of these sites are consistent with the hypothesis that if they were built in alignment with one of these former poles they would be misaligned to north as they are now as the result of subsequent pole shifts.

scholarly journals ZONES OF RECENT ACTIVATION AND SCHEME OF THE EARTH CRUST PERMEABILITY OF UKRAINE

2021 ◽  
Vol 17 (1) ◽  
pp. 75-84
Author(s):  
V.V. Gordienko ◽  
L.Ya. Gordienko ◽  
J.A. Goncharova ◽  
V.M. Tarasov
Keyword(s):  
Surface Waters ◽  
Previous Analysis ◽  
Relevant Information ◽  
Earth’S Crust ◽  
Near Surface ◽  
The Past ◽  
The Earth ◽  
Continue Research ◽  
Earth's Crust ◽  
Background Gas

An attempt is considered to supplement the criteria for identifying zones of recent activation in the territory of Ukraine with another one — data on the results of studies of helium concentration in ground-water. The previous analysis of information showed that as regional criteria, information can be applied on anomalies in heat flow, increased electrical conductivity of Earth’s crustal and the upper mantle rocks, distribution of mantle gravitational anomalies, and surface uplifts over the past millions of years. They were chosen among others precisely because of the dissemination of relevant information throughout the country. This requirement is also met by the permeability Scheme of the earth’s crust of Ukraine, which is a fragment of the permeability Scheme of the earth’s crust of the European part of the USSR based on the results of helium studies. The principal applicability of such information for solving the problem is shown. Areas of maximum helium concentrations in near-surface waters are indicated, primarily those associated with disjunctive dislocation. Theу are concentrated in the south-west of Ukraine and in Moldova. The disadvantages of the Scheme are noted, due to poor study and significant variations in background gas concentrations, directly caused not by recent activation, but by the peculiarities of helium generation by rocks of the upper part of the earth’s crust. There are inconsistencies between the previously obtained ideas about the activated zones and the data of the Scheme. They are especially large in the Carpathian, Crimean and Donetsk regions, and are noticeable in others. Therefore, it seems necessary, first, to continue research, thicken the network of observations and develop a methodology for analyzing their results.

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