|
|
Volcanic rocks and possibilities of their research using geophysical methods
Votrubcová, Kristýna ; Valenta, Jan (advisor) ; Vlček, Josef (referee)
5 Abstrakt (EN) The research focuses on the application of geophysical methods and subsequent data processing for the prospecting of igneous rocks and the search for volcanic structures. The literature review summarizes the physical and petrological foundations of various physical methods that can be utilized in the search for volcanic rocks, and discusses their most appropriate uses. The greatest emphasis is placed on the method of magnetometry, which is significant in identifying volcanoes. The work also explores the use of geoelectrical and seismic methods, radiometry, and gravimetry. In the practical section, geophysical measurements were conducted in the field to map the extent of the Tertiary volcano and other geological structures in the Elbe Sandstone Mountains. The extent of the volcanic body was successfully mapped using magnetic measurements. The results of the measured Electrical Resistivity Tomography (ERT) profile corresponded to the extent of the volcanite body and showed that the body was significantly fractured. Other findings include the mapping of a fault zone, to which the volcanic body ascend could be linked, and the mapping of another fault zone in a nearby valley, which is assumed to have a fault character. Key words: igneous rocks, volcanism, geophysics, magnetometry, VLF, ERT
|
|
|
State of the art on lightning activity induced by volcanism
Tesař, Matouš ; Popová, Jana (advisor) ; Křížek, Marek (referee)
The thesis presents a state of the art of existing knowledge and findings related to the lightning inducted by volcanic activity. First the thesis briefly characterizes lightning which occurs in thunderstorms. The chapter also presents mechanisms of lightning occurrence and methods of lightning detection. The main part of the thesis contains a literature review on the characteristics of lightning which occurs in relation to volcanic activity. It also provides classification of volcanic lightning and mechanisms of its occurrence. Furthermore, the chapter describes methods which are used to detect volcanic lightning. It also contents methods of investigation of volcanic lightning and laboratory experiments, which aim at deepening theknowledge on this phenomenon. Moreover, the chapter also provides a brief outline of expected future research on volcanic lightning. The thesis presents several ways by which volcanic lightning affects the Earth's atmosphere and surface, and the affected volcanic ash particles. Based on findings provided by the literature, the thesis discusses and compares lightning produced during in thunderstorms with volcanic lightning. Key words: lightning, volcanism, state of the art, detection
|
|
|
Impact of volcanic activity on environment and climatic conditions during geological history of the České středohoří Mts.
Zajícová, Jana ; Kvaček, Zlatko (advisor) ; Teodoridis, Vasilis (referee)
The influence of volcanoes on climate is very often debated, not only in the scientific community. However, the question remains, how much may the volcanic activity contribute to the significant ganges, that could cause a response of environment, which lies in the immediate vicinity. These changes could arise as a response on prolonged exposure of the negative influence, which would last much longer than decades, like it is at present. From this reason the situation in the České středohoří Mountains, where the volcanic activity lasted for several million years during the Paleogene period, is studied. This area is extraordinally rich in deposits of so-called volcanic floras, which accompany the neovolcanic activity. The age of the localities are between late Eocene to late Oligocene and it is a long time enough for recognizing some changes in the floristic composition to help elucidate the given problem.
|
|
|
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.
|
|
|
Impact of volcanic activity on environment and climatic conditions during geological history of the České středohoří Mts.
Zajícová, Jana ; Kvaček, Zlatko (advisor) ; Teodoridis, Vasilis (referee)
The influence of volcanoes on climate is very often debated, not only in the scientific community. However, the question remains, how much may the volcanic activity contribute to the significant ganges, that could cause a response of environment, which lies in the immediate vicinity. These changes could arise as a response on prolonged exposure of the negative influence, which would last much longer than decades, like it is at present. From this reason the situation in the České středohoří Mountains, where the volcanic activity lasted for several million years during the Paleogene period, is studied. This area is extraordinally rich in deposits of so-called volcanic floras, which accompany the neovolcanic activity. The age of the localities are between late Eocene to late Oligocene and it is a long time enough for recognizing some changes in the floristic composition to help elucidate the given problem.
|
guest ::
