scholarly journals The first results of estimating the depth of the Moho surface by the method of converted Ps-waves for the Azerbaijan part of the Greater Caucasus

2020 ◽  
Vol 2 (3) ◽  
pp. 78-87
Author(s):  
Gurban Yetirmishli ◽  
Sabina Kazimova
Keyword(s):  
Software Package ◽  
Seismic Analysis ◽  
Receiver Function ◽  
Epicentral Distance ◽  
Earth’S Crust ◽  
Mountain Building ◽  
Greater Caucasus ◽  
Gravimetric Data ◽  
The Difference ◽  
Earth's Crust

The methodology of the converted waves, or as it is commonly called, the "Receiver function" method, is well known and is widely used throughout the world to study the deep structure of the Earth up to 800 km. The method is based on the registration and interpretation of converted Ps waves. These studies were carried out as part of the International Seismotomo-graphic Laboratory using a software package developed at the University of Missouri (USA). One of the best regions for studying the early stages of mountain building is the Greater Caucasus, where most of the volcanism and mountain building appears to be 5 million years. Of particular interest is the immersion zone of the Kura Basin beneath the Greater Caucasus, the so-called subduction zone, which has not been sufficiently studied to date. To this end, we began our studies of the depth of the Moho border with this region. Thus, for the first time on the basis of the analysis of the wave characteristics of distant earthquakes recorded at seismic and telemetric stations of the RSSC, within the framework of the international project "Transect", the depths of the Moho border for the Azerbaijan part of the Greater Caucasus were refined by the method of exchange reflected Ps waves ("Receiver function"). Seismo-grams of the selected earthquakes were processed using the Seismic Analysis Code (SAC) software package under the MacOs operating system. The study examined seismological data recorded by a network of telemetry stations (N=20) for 2009-2019. In total, 2428 earth-quakes recorded at an epicenter distance of 35 to 90 degrees were analyzed. At the first stage, frequency filtering was carried out in order to eliminate oscillations that were too high, containing the effects of random scattering on inhomogeneities, and too low frequencies that re-duce the resolution. The working range of the periods ranged from two to 10 seconds. Next, two-dimensional and three-dimensional rotation of the axes was carried out. The summation of all traces was carried out with time shifts relative to some reference epicentral distance, which is assumed to be 60 degrees. On the summarized Q-tracks of the receiving functions, the Moho boundary with a delay time of 4.0 sec is clearly distinguished. Thus, a map of iso-lines of the depths of the Moho surface was constructed and depths were determined for the territory of the Guba-Gusar region 48-50 km, the Zagatala-Balakan region 46-47 km, the Shamakhi-Ismayilli region 48-52 km. As it was said earlier, the first definitions of the depth of the surface of Moho in Azerbaijan were made based on the data from the state earthquake and the gravitational model of the Earth's crust. R.M. Gadzhiev in 1965 and E.Sh. Shikhalibeyli in 1996 built such models. The data obtained are consistent with the available data, but discrepancies have been received. Compared with the map constructed according to the GSZ-KMPV and gravimetric data by R.M. Gadzhiev (1965), the difference in the thickness of the earth's crust was from one to 15 km. Compared with the map constructed according to the FGP and gravimetric data by E.Sh Shikhalibeyli (1996), the difference in the thickness of the earth's crust varied from one to 10 km.

scholarly journals V.—Effects of Alternations of Temperature on Terra Cotta Copings set in Cement as an Illustration of a Theory of Mountain Building

1888 ◽  
Vol 5 (1) ◽  
pp. 26-27
Author(s):  
T. Mellard Reade
Keyword(s):  
Permanent Deformation ◽  
Cumulative Effect ◽  
Earth’S Crust ◽  
Mountain Building ◽  
Mountain Ranges ◽  
Earth's Crust ◽  
Atmospheric Changes

Elsewhere I have shown that metals under certain conditions when subjected to changes of temperature undergo permanent deformation. Thus sheets of lead ridge up and fold even under the influence of atmospheric changes, as may be seen by the examination of any old lead flats or gutters. The cumulative effect of small but repeated changes of temperature is very striking; and I have used it in illustration of what I conceive to be the true explanation of the ridgings up of the earth's crust called mountain ranges. The examples given of the effects of alternations of temperature are mostly in metals, but I have also shown that other materials not ductile are affected in the same way. in a lesser degree.

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.

scholarly journals Inhomogeneities of the earth’s crust of the Aldan-Stanovoy shield along the 3-DV profile (Eastern Siberia, Russia

2021 ◽  
Vol 43 (3) ◽  
pp. 27-46
Author(s):  
V. V. Stogny ◽  
G. A. Stogny
Keyword(s):  
Gravitational Field ◽  
Deep Structure ◽  
Regional Metamorphism ◽  
Granite Gneiss ◽  
Earth’S Crust ◽  
Gneiss Dome ◽  
Proposed Model ◽  
Gravimetric Data ◽  
Juvenile Crust ◽  
Earth's Crust

Profile 3-DV (Skovorodino-Tommot) crosses in the sublatitudinal direction the Stanovoy and Aldan megablocks of the Aldan-Stanovoy shield. As the basic elements of the Earth’s crust section along the profile 3-DV, a technique was adopted for identifying regional inhomogeneities of the lithosphere based on the results of the analysis of seismic and gravimetric data with subsequent typification of their nature. According to the SRM-CMP data, in the upper part of the section (up to 35 km) of the Aldan megablock, the Yakokut and Chulman heterogeneities are distinguished, and the Stanovoy megablock — the Kalara-Dzhugdzhur heterogeneity. The Yakokut and Chulman seismic inhomogeneities in the gravitational field correspond to minima with an the amplitude of up to 25 mGal. The gravitational field of the Kalara-Dzhugdzhur heterogeneity is mosaic and reflects its block structure. It is shown that the deep structure of the Aldan megablock in the area of the 3-DV profile is determined by the Yakokut granite-gneiss dome and Chulman sublateral decompaction zone, and the upper part (0—25 km) of the Stanovoy megablock is represented by the Kalar-Dzhugdzhur structure, composed of the Stanovoy complex of rocks  and blocks of highpressure granulites. A significant (up to 10 km) increase in the thickness of the earth’s crust of the Aldan megablock is explained by the presence of the upper layer juvenile crust formed in the Paleoproterozoic as a result of regional metamorphism of igneous rocks. The Earth’s crust of the Stanovoy megablock is tectonically rebuilt for almost the entire thickness of up to 40 km during the Mesozoic collision of the Precambrian North Asian and Sino-Korean cratons. The Yakokut granite-gneiss dome, in accordance with the proposed model of the structure of the Earth’s crust of the Aldan megablock, is the ore-controlling structure of the Central Aldan gold-bearing region, and highpressure granulites of the Zverevsky block of the Kalara-Dzhugdzhur heterogeneity of the Stanovoy megablock served as a source of gold in the Chako-Berkakit ore cluster.

scholarly journals I.—On some Physical Changes in the Earth's Crust

1889 ◽  
Vol 6 (2) ◽  
pp. 49-53 ◽  
Author(s):  
Charles Ricketts
Keyword(s):  
Earth’S Crust ◽  
Mountain Building ◽  
Volcanic Origin ◽  
Earth's Crust ◽  
Physical Changes

There always appears an objection to the agencies by which mountains and hills are formed being designated by such terms as “mountain architecture,” “ mountain building,” etc., leading to the inference that to the deposition of the materials which enter into their composition these elevated regions owe their form and structure. There certainly are mountains which have been built, and some such are at the present time in process of building; but these instances refer only to elevated masses of volcanic origin: they have been constructed as the railway engineer builds his embankments, or, with greater preciseness, as the miner forms the bank at the pit's mouth, by tipping over the rubbish brought from below. To hills and mountains forming volcanic cones the term mountain building is quite correct; the volcano in eruption pouring over its lava, and belching forth scoriæ and ashes, which fall and accumulate around its vent.

A study of the Earth's crust near Gauribidanur in Southern India

1971 ◽  
Vol 61 (3) ◽  
pp. 671-683
Author(s):  
S. K. Arora
Keyword(s):  
Epicentral Distance ◽  
Earth’S Crust ◽  
Seismic Events ◽  
Travel Times ◽  
Geological Features ◽  
Local Earthquake ◽  
First Arrival ◽  
Earth's Crust ◽  
Relative Differences ◽  
Granitic Layer

abstract A hypothetical two-layered model has been evolved for the Earth's crust near Gauribidanur. The model is found to be consistent with the local earthquake and rockburst data obtained at Gauribidanur seismographic array. Sixty-seven well-recorded seismic events have been studied for this purpose. First arrival conditions for some of the phases in a “near-source” (epicentral distance Δ ≦ 10°) seismogram have been derived and subsequently made use of in establishing the nature of the first arriving phases pertaining to the available data. Thickness of the top granitic layer and the depth of Moho below this layer are found to be about 16 km and 19 km, respectively. Observed velocities are 5.67, 6.51 and 7.98 km/sec for P phases, and 3.46, 3.96 and 4.61 km/sec for the corresponding S phases. Values of the crustal parameters given by this study have been used in estimating the relative differences in travel times corresponding to various observed phases. These travel times may improve the precision with which earthquakes in this region could be located. Typical geographical and geological features of the region are also briefly described.

Sign in / Sign up

Export Citation Format

Share Document