scholarly journals Уточнение гипоцентров землетрясений методом двойной разности

2020 ◽  
pp. 41-51
Author(s):  
S.E. Kazimova
Keyword(s):  
Velocity Model ◽  
Earth’S Crust ◽  
Seismic Survey ◽  
Double Difference ◽  
Mutual Arrangement ◽  
Seismic Events ◽  
One Dimensional ◽  
Good Convergence ◽  
Earth's Crust ◽  
The One

In the last decade, significant advances have been made in the theory and application of seismic tomography. These include refinements in model parameterization, 3D ray tracing, an inversion algorithm, sharing local, regional, and teleseismic data, and adding transformed and reflected waves to tomographic inversion. Explorations have shown that with the help of seismotomography it is possible to obtain reliable data on the deep structure of the Earth, its thickness, the mutual arrangement of layers, as well as tectonic structures identified in the earth’s crust. Due to a significant increase in the number of seismic stations in the Republican Seismic Survey Center and equipping them with modern instruments of the MacOs system (made by “Kinemetrics”), it was possible to obtain a large volume of observed seismic material and solve rather complex methodological issues, which is relevant today. The aim of this article is to redefine the data of the hypocenters of earthquakes that occurred on the territory of Azerbaijan for the period 2010‑2019 (ml>2.0) and calculate the velocity model of the earth’s crust using algorithms that are not included in the mandatory processing when compiling a catalog of seismic events. The catalog data were taken from the “Bureau of Earthquake Research” of the Republican Seismic Survey Centerof Azerbaijan National Academy of Sciences. Research methods. Within the framework of present work, using the double difference method, we redefined the location of seismic events, showing that the obtained positions of the epicenters are lined up in systems of linear chainsalong the main and feathering faults, which is consistent with the relief and geological concepts. Results. Comparing the values of the velocities with the values of the one-dimensional velocity model, it was found that at depths of 5‑10 km, there is good convergence in the regions of the Greater Caucasus. The middle Kura depression is mainly characterized by low velocities compared to the one-dimensional velocity model. At a depth of 15 km, the eastern part of the Middle Kura depression is characterized by good convergence, but in the western part high velocities are noted. The maximum convergence of velocities was noted at a depth of 35 km В последнее десятилетие были достигнуты значительные успехи в теории и применении сейсмотомографии. К ним относятся уточнения в параметризации модели, трас- сировка трехмерных лучей, алгоритм инверсии, совместное использование локальных, региональных и телесейсмических данных, а также добавление преобразованных и отраженных волн в томографическую инверсию. Исследования показали, что с помощью сейсмотомографии можно получить достоверные дан- ные о глубинном строении Земли, ее толщине, взаимном расположении слоев, а также о тектонических структурах, выявленных в земной коре. Благодаря значительному увеличению числа сейсмических стан- ций в РЦСС, оснащению их современными приборами системы MacOs (фирсы «Кинеметрикс»), удалось получить большой объем наблюденного сейсмического материала и решить довольно сложные методи- ческие вопросы, что является актуальным на сегодняшний день. Целью данной статьи является пере- определение данных гипоцентров землетрясений произошедших на территории Азербайджана за период 2010‑2019 гг. (ml>2,0) и вычислению скоростной модели земной коры с использованием алгоритмов, не входящих в обязательную обработку при составлении каталога сейсмических событий. Данные каталога были взяты в «Бюро исследований землетрясений» РЦСС при НАНА. Методы исследования. В рамках дан- ной работы методом двойных разностей мы переопределили положения сейсмических событий, показав, что полученные положения эпицентров выстраиваются в системы линейных цепочек, положение которых согласуется с рельефом и геологическими представлениями, располагаясь вдоль главного и оперяющих разломов. Результаты работы. Сопоставляя значения скоростей со значениями одномерной скоростной модели, установлено что на глубинах 5‑10 км наблюдается хорошая сходимость в областях Большого Кавказа. Среднекуринская депрессия в основном характеризуется малыми скоростями по сравнению с одномерной скоростной моделью. На глубине 15 км восточная часть Среднекуринской депрессии характе- ризуется хорошей сходимостью, однако в западной части отмечены завышенные скорости. Максимальная сходимость скоростей отмечена на глубине 35 км

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.

scholarly journals THE SAMOTHRACE EARTHQUAKE OF MAY 2014 AND THE DISPLACEMENTS ESTIMATIONS USING PERMANENT GPS STATIONS DATA

2017 ◽  
Vol 50 (3) ◽  
pp. 1545 ◽  
Author(s):  
S. Bitharis ◽  
A. Fotiou ◽  
C. Pikridas ◽  
D. Rossikopoulos ◽  
S. Pavlides ◽  
...  
Keyword(s):  
Strong Earthquake ◽  
Satellite Observations ◽  
Earth’S Crust ◽  
Seismic Events ◽  
Aegean Area ◽  
The North ◽  
North Aegean ◽  
Geometrical Information ◽  
Gps Networks ◽  
Earth's Crust

The contribution of GPS networks in monitoring seismic events is important because they can provide a direct geometrical information on the Earth's crust using satellite observations In this study position displacements of permanent GPS stations are determined due to intense seismic events in the North Aegean area after the strong earthquake on May 24, 2014. The horizontal coseismic displacements for the Samothrace Island were estimated at 9.4 cm and for Lemnos Island at 5.2 cm respectively. A study period of seven days was enough to show that the deformation evolved into two days.

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.

Notices of the Volcanic Rocks and Geysirs of Iceland

The Geologist ◽  
1858 ◽  
Vol 1 (4) ◽  
pp. 142-146
Author(s):  
J. E. Vaux
Keyword(s):  
Safety Valve ◽  
Volcanic Rocks ◽  
Internal Heat ◽  
The Other ◽  
Earth’S Crust ◽  
High Latitudes ◽  
The World ◽  
Earth's Crust ◽  
The One

Of all the wondrous changes which nature has wrought on the earth's crust, there is scarcely anything that will bear comparison with those which meet the eye of the traveller in volcanic regions. Of the two great agents in. Geological transformation—water and fire, the one moves us with admiration at the delicacy of its operations, the other strikes us with awe at the mightiness of its influences, and the rapidity of its work.Few, if any, countries present ua with such remarkable or various manifestations of the potency of subterranean heat as Iceland. So much so, indeed, that it appears as though it were the acknowledged safety-valve, in this portion of our globe at least, through which the troubled contents of depths unknown may, on any emergency, find a ready vent.Interest more than ordinary appears to have been taken of late in this most remarkable region. No less than six parties of tourists having, during the year before last, investigated the natural marvels of the island. One of these adventurers, Lord Dufferin, in a most interesting and amusing book, has given to the world a record of his travels. From his “Letters from High Latitudes” we propose to quote his graphic picture of the result of volcanic action, in producing a very remarkable and very manifest change in the aspect of the large tract of country to which that portion of hiB narrative refers.But before we proceed to this, it may perhaps be useful to recal to the reader's recollection the two theories which have, up to the present time, been put forth with respect to the causes of internal heat, and hence to the origin of volcanic action in general.

scholarly journals Analysis of the features of the spatio-temporal distribution of geoelectric inhomogeneities in the Earth’s crust and seismic events

2021 ◽  
Vol 254 ◽  
pp. 02003
Author(s):  
Elena Bataleva
Keyword(s):  
Temporal Distribution ◽  
Physical Nature ◽  
Tien Shan ◽  
Earth’S Crust ◽  
Seismic Events ◽  
Magnetotelluric Data ◽  
Geological Conditions ◽  
Spatio Temporal ◽  
Earth's Crust ◽  
The Relationship

The paper presents the results of experiments carried out at the regime points of magnetotelluric monitoring both on the territory of the Bishkek geodynamic test site (Northern Tien Shan) and on a series of monitoring profiles in various geological conditions. Previous studies indicate the relationship of variations in the electromagnetic and seismic fields, lunisolar tidal effects, seismic regime with the processes of fracturing. The purpose of this work is to establish the features of the relationship between the spatio-temporal distribution of seismicity and the distribution of geoelectric inhomogeneities in the Earth’s crust (fault-block tectonics of the region). Based on the analysis of the results of the interpretation of magnetotelluric data (2D inversion) and new detailed seismotomographic constructions, the verification of geoelectric models was carried out, the analysis of the distribution of hypocenters of seismic events was carried out. Special attention was paid to the confinement of earthquakes to listric fault structures. The relationship between the distribution of the hypocenters of seismic events and the spatial position of the electrical conductivity anomalies is confirmed by the authors explanation of the physical nature of the identified conducting structures, based on hypotheses of fluidization and partial melt of the Earth’s crust.

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 The Geology of the Sea

The Geologist ◽  
1860 ◽  
Vol 3 (07) ◽  
pp. 241-249
Author(s):  
S. J. Mackie
Keyword(s):  
Structural Change ◽  
Crystalline State ◽  
Internal Heat ◽  
Hot Water ◽  
The Other ◽  
Earth’S Crust ◽  
The Common ◽  
Earth's Crust ◽  
The One ◽  
Double Entry

No man is right at all times, says the common proverb, and Geologists are not always exceptions to the rule. Granite has been looked upon as the “back-bone” of the earth's crust, and fire or deeply-seated internal heat has been supposed to have fused an ancient unknown kind of rock into its present compact and crystalline state, while although now scarcely anything more than, at most, hot water will be allowed as an agent in the structural change. The older geologists invoked on all occasions when great effects were to be produced most terrible commotions and catastrophes, just as melodramatists bring in blue fire and demons. Nature is, however, a most methodical business personage. Sedate and steady, she takes quietly and methodically everything with which she has to do, and keeps her accounts properly by double entry. If you draw on her on the one hand, immediately she pays into her bankers on the other. Nothing goes down on the one side of her accounts but instantly she makes some entry on the other.

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