National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Time-domain electromagnetics and its applications for prospection of maar volcanoes
Fait, Václav ; Valenta, Jan (advisor) ; Klanica, Radek (referee)
In this work I study the advanced geophysical method - the time domain electromagnetics. In the theoretical part I summarize principles of the method, describe several measuring systems and guide the reader through the software for data processing. I further prove reliability of the applied methodology by forward and inverse computations for a simplified model of supposed target structures. The results show that for the selected configuration of field measurements with a depth range of 100-200 m the influence of 3D structures is significant when placed in a distance smaller than approximately 100 m. In the practical part I test the method in the sedimentary environment and find that results of the method are in accordance with the vertical electrical sounding method. Subsequently, I show that the artificial highly conductive object placed inside the current loop significantly affects the outcomes of the method. Artificial conductive object has only minute effect if placed in a close distance but outside of the current circuit. Besides the theoretical and experimental findings about the reliability of the method I have applied the method for research of maar volcanoes. I have confirmed with high probability the presence of maar volcano near the Jablonná village. The results measured close to the...
Geophysical prospection of volcanic structures, in the area of Rybí loučky, Jizerské mountains
Fait, Václav ; Valenta, Jan (advisor) ; Skácelová, Zuzana (referee)
This thesis briefly depicts fundamental principles of three geophysical methods (gravimetry, magnetometry and electrical resistivity profiling), which had been used during research at the Rybí lou ky site in order to clarify local geological conditions. Furthermore, the reader gets acquainted with formation of a maar-diatreme, which is thought to be present at the researched site. The next part describes principles of field measurements and the procedure for evaluation of results. The results are graphically plotted in the last part. Also, the results are compared to previous investigations conducted at this site. Geophysical measurements showed that geological structures on the Rybí lou ky site are much more complex than expected. The simple diatreme structure is most likely not applicable in this case. In contrast, it is not a structure formed solely by a glacier. The origin is most likely a combination of tectonic predisposition, volcanic activity and subsequent selective erosion.

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