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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Statistická analýza katalogů přirozené a indukované seismicity / Statistical analysis of natural and induced seismicity catalogues

Mazanec, Martin January 2017 (has links)
The main goal of this thesis is to analyze the statistical properties of seismic catalogues of natural and induced seismicity, identify similarities and differences. We compare statistical temporal and magnitude information contained in different types of earthquake catalogues. Six seismostatistical criteria used for identification of natural swarms and mainshock- aftershock earthquake sequences are applied to 10 different catalogues of natural and induced seismicity. We did not find a method to reliably distinguish between natural and induced seismicity based only on temporal and magnitude information contained in catalogues. We show that induced seismicity catalogues are similar to natural earthquake swarms. We report how the set of 6 criteria presented here can be used for distinguishing between mainshock-aftershock sequences and swarm seismicity. We also show that none of the tested criteria can be used independently for distinguishing between different types of seismicity.
2

Understanding the evolution of channeling and fracturing in tight rocks due to fast fluid flow / Comprendre l'évolution de la formation de canaux et de la fracturation des roches dures liée à l'écoulement à grande vitesse d'un fluide

Turkaya, Semih 10 November 2016 (has links)
Depuis de nombreuses années, la compréhension de l'influence des fluides dans la déformation des roches est un enjeu majeur pour de nombreux scientifiques. Dans le cadre de ce projet de recherche, notre attention s’est focalisée sur l’observation et la modélisation des mécanismes d’interaction entre les parties fluide et solide lors de l’aérofracturation d’un milieu poreux. Notre dispositif expérimental reproduit le phénomène à basse pression et dans un système pertinent pour l’analyse optique, grâce à une cellule de Hele‐Shaw rectangulaire dans laquelle se trouve un milieu granulaire soumis à des écoulements de fluide interstitiel. Dans les expériences et les simulations nous avons observé ce que l’amplitude de la partie de fréquence basse du spectre puissance diminue avec la fracturation en progrès. Aussi, nous avons développé une méthode pour focaliser les ondes ce qui peut être utiliser pour estimer la position de la source. / Fluid induced brittle deformation of porous medium is a phenomenon commonly present in everyday life. From an espresso machine to volcanoes it is possible to see traces of this phenomenon. In a rectangular Hele‐Shaw cell we inject air into a loose porous medium. Then, we monitor this system using optical imaging using a high speed camera (1000 fps) and 4 high frequency resolution accelerometers. Using the numerical and experimental acoustic emissions, different sources of the recorded signal (vibrations due to air, changes in the effective stress due to fluid‐solid interactions) are analyzed. We found that, the peaks in the low frequency range (f < 20 kHz) diminishes while the medium fractures. Furthermore, we propose a new signal localization method based on energy amplitude attenuation and inversed source amplitude comparison. Furthermore, using optical and acoustic datasets and numerical simulations, the mechanics leading Type‐A and Type‐B earthquakes are explained.

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