scholarly journals The pecularities of shear crack pre-rupture evolution and distribution of seismicity before strong earthquakes

2001 ◽  
Vol 1 (3) ◽  
pp. 145-158 ◽  
Author(s):  
D. Kiyashchenko ◽  
V. Troyan

Abstract. Several methods are presently suggested for investigating pre-earthquake evolution of the regions of high tectonic activity based on analysis of the seismicity spatial distribution. Some precursor signatures are detected before strong earthquakes: decrease in fractal dimension of the continuum of earthquake epicenters, cluster formation, concentration of seismic events near one of the nodal planes of the future earthquake, and others. In the present paper, it is shown that such peculiarities are typical of the evolution of the shear crack network under external stresses in elastic bodies with inhomogeneous distribution of strength. The results of computer modeling of crack network evolution are presented. It is shown that variations of the fractal dimension of the earthquake epicenters’ continuum and other precursor signatures contain information about the evolution of the destruction process towards the main rupture.

2000 ◽  
Vol 5 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Guangming Yu ◽  
Heping Xie ◽  
Jianfeng Zhoa ◽  
Lun Yang

A quantitative description for the spatial distribution and the evolution of a crack network in mining rock stratum is one of the most difficult and fundamental problem in the subject of surface subsidence. In this paper, the physical models are employed to simulate the spatial distribution of a crack network. By using the fractal geometry, the self-similarity of spatial distribution of crack network is discovered. As a result, the conception of fractal crack network is proposed. Furthermore, the evolution of a crack network with the increasing of mining width is investigated. It is shown that (1) the spatial distribution of a crack network displays the fractal behavior, so, the fractal dimension can be used to describe quantitatively the evolution of the crack network, (2) the fractal dimension of the crack network increases with increasing of mining width, (3) the surface subsidence increases with the increasing of fractal dimension of crack network.


Author(s):  
Л.И. Морозова ◽  
А.В. Николаев ◽  
С.А. Пулинец

В работе делается попытка обобщить результаты наблюдений еще до конца не понятого явления, обычно называемого «линейные облачные аномалии» (ЛОА), наблюдае- мого над областями подготовки сильных землетрясений или интенсификации тектонической активности. В англоязычной литературе можно найти более лаконичное называние «earthquakeclouds». Несмотря на достаточно богатую литературу по этому вопросу, до сих пор остается не выясненной физическая при- рода ЛОА. Цель работы. Именно выяснения физического механизма формирования ЛОА перед землетря- сениями приставляет собой наиболее актуальную задачу. В данной работе мы делаем шаг впередв данном направлении, потому что основной целью нашего исследования является поиск источников формирова- ния ЛОА. Методы исследования. Нами получены экспериментальные доказательства, что ЛОА всех типов имеют зародышевые структуры в нижней атмосфере на уровне порядка 100 м от поверхности Земли, что доказывает связь генезиса ЛОА с процессами, инициируемыми в земной коре. Источником информации, используемой для проверки процессов формирования ЛОА, являются метеорологические данные, полу- чаемые из ассимилятивной модели GEOSFP, получаемые вблизи поверхности земли. Результаты работы. Сделана попытка проследить генезис ЛОА от поверхности земли до уровня сформировавшейся облач- ной структуры, и предложен физический механизм генерации ЛОА, в том числе поддержания их геоме- трической линейности в условиях турбулентной атмосферы. Данная работа была задумана совместно с ушедшим от нас А. В. Николаевым, мы постараемся включить в работу всё, что обсуждалось с ним при её подготовке, в том числе с учетом его принципиального мнения, что «неясность физических принципов не может быть причиной недоверия к экспериментальным результатам». Ключевые слова: линейные облачные аномалии, землетрясение, облачная гряда, прогноз землетря- сений An attempt is made in present paper to generalize the results of observations of the not yet fully understood phenomenon, usually called “linear cloud anomalies” (LCA), observed over the areas of impending strong earthquakes or intensification of tectonic activity. In the English-language literature, you can find a more concise name “earthquake clouds”. Despite the fairly rich literature on this issue, the physical nature of LСA remains unclear. Aim. It is the identificationof the physical mechanism of the formation of LCA before earthquakes that is the most urgent problem. In this work, we take a step forward in this direction, because the main aim of our study is to find the sources for the formation of LCA. Methods. We have obtained experimental evidence that LCA of all types have embryonic structures in the lower atmosphere at a level of about 100 m from the Earth’s surface, which proves the connection between the LCA genesis and the processes initiated in the earth’s crust. The source of information used to verify the formation of LCA is the meteorological data obtained near the earth’s surface from the assimilative model GEOS FP. Results. An attempt is made to trace the genesis of LСA from the earth’s surface to the level of the formed cloud structure, and a physical mechanism for the generation of LСA is proposed, including maintaining their geometric linearity under conditions of a turbulent atmosphere. This work was conceived together with A. V. Nikolaev, we will try to include in the work everything that was discussed with him during its preparation, including his principled opinion that “the lack of clarity of physical principles cannot be the reason for distrust of experimental results


2016 ◽  
Vol 16 (3) ◽  
pp. 563-573 ◽  
Author(s):  
Tingting Wang ◽  
Wanchun Zhao ◽  
Dan Zhao ◽  
Dongfeng Jiang

2001 ◽  
Vol 15 (06n07) ◽  
pp. 912-917
Author(s):  
HISAO MORIMOTO ◽  
TORU MAEKAWA

We developed a statistical model of the cluster formation of ferromagnetic particles and analysed the cluster structures. We investigated the effect of the control parameter λ, that is, the ratio of magnetic dipole moment energy to thermal energy, and external magnetic fields on the fractal dimensions of three-dimensional ferromagnetic clusters. We found that the fractal dimension of clusters, D, changes from 5/3 to 2 as λ increases in the absence of a magnetic field. We also found that when clusters are subjected to a magnetic field, the fractal dimension decreases and the transition region from high fractal dimension to D=1 becomes shorter as λ increases.


2020 ◽  
Vol 8 (5) ◽  
pp. 2473-2480

The increasing need for portable and flexible communication has paves a way for network evolution amongst unmanned aerial vehicles (UAVs) which is known as FANETs. Moreover, owing to its exclusive features of UAVs like frequency topology, high mobility and 3D movement makes routing most confronting task in FANETs. With these features, designing novel clustering model is quite complex. In general, topology based routing is determined as significant factor for resolving routing crisis. Henceforth, this investigation specifically spotlights on topology based routing protocol termed as Fuzzy based Markov chain Cluster (FMCC) with an objective of enhancing efficiency of networks in terms of resource utilization, time delay, transmission ratio and resource availability. Initially, consider a network model and the problems related in constructing a network without loss of packet transmission, neighbourhood construction and so on. In this work, simulation is done in NS-2 simulator and outcomes are analyzed based on end-to-end delay, throughput, cluster formation, cluster lifetime and so on. This method depicts better trade off in contrast to prevailing techniques. The information associated with the information exchange is considered for renovating the work effectually.


2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Tao Liang ◽  
Xiaoli Liu ◽  
Sijing Wang ◽  
Enzhi Wang ◽  
Quansheng Li

The evolution and distribution of fracture network induced by mining is essential to determine the mechanical properties and permeability of disturbed rock mass. In this paper, the similar material model tests are employed to simulate the stress variation, cyclic breaking, and fracture formation and distribution status of the overlying strata with different loading conditions, rock properties, and mining process. The fractal dimension of mining-induced fracture network varied with mining advancing, and the evolvement laws of fracture network with mining advancing and different mining advancing footage are concerned and obtained. By establishing the relationship between the fractal dimension and the mining length in different horizontal and vertical zones, it demonstrates that the fractal dimensions in horizontal and vertical zones have a self-similar characteristic, and the distribution of the fractal dimension of the mining-induced fractures shows generally the “W”-type trend.


2021 ◽  
Vol 7 (1) ◽  
pp. 84-97
Author(s):  
Valery Yanchukovsky

Using the results of continuous long-term observations over 50 years (including solar cycles 20–24), we study the relationship between Earth’s seismicity and solar activity. An increase in the number of strong earthquakes on the planet occurs during the decline phase of solar activity when charged particle fluxes from high-latitude coronal holes increase, as well as during solar minimum when the intensity of galactic cosmic rays reaches a maximum. The change in the number of strong earthquakes (with magnitude 6) is considered in terms of variations in the intensity of galactic cosmic rays, Forbush decreases, and ground level enhancements in solar cosmic rays (GLE events). The number of strong earthquakes is shown to increase after Forbush decreases with a time lag from ~1 to ~6 days depending on the amplitude of Forbush decrease and after GLE events the number of strong earthquakes increases by ~8 day. In the number of strong earthquakes, a six-month variation is observed, which seems to follow the six-month variation in cosmic rays with a delay of ~1–2 months. It is surmised that the relationship between solar activity and Earth’s seismicity seems to be mediated through the modulation of galactic cosmic rays and atmospheric processes that provoke the occurrence of earthquakes in regions where the situation has already been prepared by tectonic activity.


2021 ◽  
Vol 7 (1) ◽  
pp. 67-77
Author(s):  
Valery Yanchukovsky

Using the results of continuous long-term observations over 50 years (including solar cycles 20–24), we study the relationship between Earth’s seismicity and solar activity. An increase in the number of strong earthquakes on the planet occurs during the decline phase of solar activity when charged particle fluxes from high-latitude coronal holes increase, as well as during solar minimum when the intensity of galactic cosmic rays reaches a maximum. The change in the number of strong earthquakes (with magnitude 6) is considered in terms of variations in the intensity of galactic cosmic rays, Forbush decreases, and ground level enhancements in solar cosmic rays (GLE events). The number of strong earthquakes is shown to increase after Forbush decreases with a time lag from ~1 to ~6 days depending on the amplitude of Forbush decrease and after GLE events the number of strong earthquakes increases by ~8 day. In the number of strong earthquakes, a six-month variation is observed, which seems to follow the six-month variation in cosmic rays with a delay of ~1–2 months. It is surmised that the relationship between solar activity and Earth’s seismicity seems to be mediated through the modulation of galactic cosmic rays and atmospheric processes that provoke the occurrence of earthquakes in regions where the situation has already been prepared by tectonic activity.


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