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Seismograph installation and complex analysis of recorded data
Vaško, Oskar ; Fischer, Tomáš (advisor) ; Hrubcová, Pavla (referee)
This thesis deals with assembly of a school seismograph and a common analysis of recorded data. A garden-gate type seismometer was assembled within the first part of my thesis. The pendulum construction of the seismometer enables recording of a horizontal component of seismic signal. The data analysis involves mainly processing of seismic noise in the buiding of Geologic Section of Faculty of Science in Prague - Albertov. Several eigenfrequencies of the building, which indicate the liability of the construction to be affected by ground motions, were found. As a supplement few recorded earthquakes were identified. The seismic noise analysis led to a finding of a relation between eigenfrequency variation and outdoor temperature in the form of a positive correlation between daily temperature average and eigenfrequency.
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Magnitude calibration of seismic network WEBNET
Kolář, Dominik ; Fischer, Tomáš (advisor) ; Jakoubková, Hana (referee)
This thesis deals with determination of seismic magnitudes of West-Bohemian earthquakes. The first part summarizes basic information from the field of seismology and also about the earthquake swarms in the area of interest. The second part deals with calibration of magnitudes, i.e. determination of coefficient that corrects for attenuation and station corrections. Seismic data from the WEBNET network from 2012 were used to this purpose. In order to suppress tradeoff among the studied parameters the data were filtered and also usage of a fixed hypocenter depth was tested. The results show that the optimum attenuation correction is smaller than that used so far magnitude determination. It turns out that a deeper analysis is needed in order to find an optimum formula for magnitude determination at the West-Bohemia WEBNET network.
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Analysis of coda waves of the West-Bohemian earthquakes
Bachura, Martin ; Fischer, Tomáš (advisor) ; Vavryčuk, Václav (referee)
Coda of high frequency earthquakes contains information about attenuation propetries of the environment between earthquake hypocentre and seismic station. By application of different methods of coda anlysis one can derive these properties. I applied three methods to seismograms from autumn 2011 from WEBNET network monitoring seismic activity in West Bohemia/Vogtland area: basic method to derive Qc parameter of the environment, and two methods that allow for separation of intrinsic attenuation (Qi) and attenuation due the scattering (Qsc): method MLTWA (Multiple Lapse Time Window Analysis) and method based on energy flux model. Values of Qc are relatively small (from 22 to 600, which depends on the length of the window in which the analysis is carried out and on the frequency and station used), which is in good agrement with the high seismic activity in the area. Qc shows frequency, depth and lateral dependances. It increases with frequency and depth and in the southwest direction. The applicability of methods for separation of Qi and Qsc are limited. With short hypocentral distancies as we have coda is not affected by scattering. Because of this, I was unable to use MLTWA method and the method of energy flux model was usable to derive only the values of Qi. These values are from 120 (1,5 Hz at...
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Earthquake source models
Adamová, Petra ; Šílený, Jan (advisor) ; Fischer, Tomáš (referee) ; Gallovič, František (referee)
The earthquake source is routinely modeled by moment tensor description. In many cases we need more information about the source process and for that reason we occupy with higher degree moments. This approach allows us to esti- mate non-point characteristics (including some dynamic parameters): geometry of the source, duration of the source process, average slip on the fault, spatial and temporal centroid and rupture velocity vector within the point source ap- proach. This description includes 20 parameters - 6 parameters for standard moment tensor (MT) and 14 parameters for second degree moments (SDM). First, we studied synthetic tests. Large amount of significant earthquakes con- tains false non-DC component which can be caused by approximation finite source by point source. This hypothesis was proved on the case of unilateral rupture. Standard MT contains more than 20 % non-DC components which was reduced to 6 %. In the second part we applied this procedure to real data. We chose large earthquakes (Mw>6) with large non-DC component. We estimated second degree moments for them and compared them with previous studies. Moreover we restitute higher degree moments from data and proved that false non-DC component were caused by source finiteness. In the last part we applied this method to mining data and...
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Natural CO2 outburst and their relation to tectonic processes
Balák, František ; Fischer, Tomáš (advisor) ; Kolínský, Petr (referee)
This thesis is deals with the running geodynamic activity of NW Bohemia, where frequent earthquake swarms and natural CO2 emanations occur as a possible fade-out of the Tertiary rift activity. The first part summarizes the nature of these geological phenomena with a focus on CO2 escapes and its characteristics. These escapes are viewed from the viewpoint of geology and chemical and isotopic composition along with the effect of earth tides, barometric pressure and seismic activity. In the second part I analyse the records of two CO2 monitoring stations in terms of atmospheric pressure and ambient temperature.
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Seismic noise analysis at selected stations of the WEBNET network
Bachura, Martin ; Fischer, Tomáš (advisor) ; Růžek, Bohuslav (referee)
Seismic signal is affected by noise of non-geological origin. The main source of seismic noise is in human activities. Seismic noise of human origin occurs in the frequency range from one to the first tens of Hz. The noise intensity limits the lower level of the earthquake size that can be recorded by a seismic network. The aim of this thesis is to analyze the seismic noise on selected stations of the West Bohemian seismic network WEBNET which operates in the area since the early nineties. The earthquakes in West Bohemia/Vogtland are manifested in the form of long-lasting earthquake swarms with the magnitudes ranging up to ML = 3.8. The way how the seismic noise influences the seismic stations and their capability of recording small earthquakes can be classified by a statistical and time-frequency analysis. We applied this method to the selected stations NKC, KRC and SKC. The results show that the effect of noise does not deteriorate the seinsitivity of the three stations for recording small earthquakes. Despite of quite good results, some differences occur among the three stations, which are most probably caused by the distance of the stations to the populated areas. The smallest noise influence is observed at the stations located far from settlement (NKC and KRC) compared to the station located in a small...
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Relation of the alteration of the basement of the Cheb Basin and CO2 discharge
Arnetová, Kateřina ; Fischer, Tomáš (advisor) ; Boušková, Alena (referee)
The area or West Bohemia is typical by an increased geodynamic activity, which manifests itself in earthquake swarms and surface emanations of CO2 of mantle origin. These phenomena are concentrated in the tertiary Cheb basin, which is fragmented by a network of faults. The CO2 of deep origin passes along these faults to the surface and contributes to the alteration of both the basement of the basin and sedimentary infill. The aim of this thesis is to give an overview of the studied area and, with the use of well data, to verify whether the basement does show lateral changes in weathering that could indicate influence of CO2. The results show that the alteration of the basement is unequal, however no relation between the alteration and surface gas flux was found.
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Injection-induced seismicity: statistic and energetic analysis
Vlček, Josef ; Fischer, Tomáš (advisor) ; Horálek, Josef (referee)
Fluid injection into the rock formations represents a valuable analog to study the role of high-pressurized fluids in the seismogenic process. It is carried out in depths up to first thousands of meters in order to increase the permeability of rock formation for better exploitation of hydrocarbons and geothermal energy. The increased fluid pressure results in decrease of the strength of fractures and faults which causes their brittle failure that is observed in the form of microearthquakes and enables imaging of the stimulated rock volume. Besides this positive role, seismicity sometimes increases to the level that can be felt by the population, which can cause concerns about the seismic risk of these industrial operations. Thus, one of the main interests focused by recent studies deals with the maximum earthquake that can be triggered by hydraulic stimulations. I introduce the ratio between the hydraulic energy and released seismic energy, the seismic efficiency of injection, to assess the effect of fluid injection to the seismicity. This parameter is applied to data from two geothermal reservoirs (Gross Schönebeck and Soultz-sous-Forets) and one gas reservoirs (East Texas). We find that for different data sets, the seismic efficiency encompasses a broad range of magnitudes; from about 10-6 to...
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3D seismic interpretation and model of the Schrattenberg fault system in the Valtice area
Hlaváčková, Šárka ; Fischer, Tomáš (advisor) ; Buchta, Štěpán (referee)
3D SEISMIC INTERPRETATION AND MODEL OF THE SCHRATTENBERG FAULT SYSTEM IN THE VALTICE AREA Šárka Hlaváčková Abstract The Schrattenberg normal fault system represents a dominant feature of the western margin of the Vienna Basin. Along with the Steinberg fault, they controlled the sedimentary and tectonic development of the area, and considerably participated in the deposition of the basin fill during a relatively short period of time in the Miocene. A detailed interpretation of the fault system is essential for full understanding of the local basin development and its geological architecture. The oil exploration industry targets mainly the Steinberg and Schrattenberg fault system because of the occurrences of oil and natural gas deposits that are related to the basin tectonics, which forms structural traps sealed by the main fault systems or by minor synthetic or antithetic faults. The thesis presents a geological framework of the Mistelbach block near Valtice at the western margin of the Vienna Basin. Geological interpretation includes also the fault framework modeling with the emphasis on the course of the Schrattenberg fault system. The model was built in the Petrel interpretation software with the use of the principles of the 3D seismic interpretation. In particular, seismic stratigraphy methods, Petrel...
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The geological evolution of the Vienna basin and interpretation of seismic profiles across the western margin of the basin
Hlaváčková, Šárka ; Fischer, Tomáš (advisor) ; Berka, Jiří (referee)
The geological evolution of the Vienna basin and interpretation of seismic profiles across the western margin of the basin Abstract The Vienna basin represents an example of a Neogene pull-apart basin developed between two orogenic systems - the Eastern Alps and West Carpathians. Their different Miocene geodynamic played the key role in opening of the basin. The pull-apart mechanism was significantly influenced by a rotation in the Middle Miocene. This thesis summarize the geodynamic development of the basin with regard to Tertiary evolution of the wider Carpathian - Panonnian area and paleomagnetic description of a rotation of ALCAPA unit. The Lower Miocene basin is superimposed on stack of nappes of the Alpine - Carpathian thrust belt. It was formed as a piggy-back basin on the top of overthrusted nappes. During the Karpathian, a new tectonic settings was established, due to the change of geodynamics within the Alpine - Carpathian area. In the Badenian, the important NE - SW trending faults were developed. The Steinberg and Schrattenberg synsedimentary faults considerably participated in the formation of the west margin of the Vienna basin, and controlled a deposition of the Neogene sedimentary fill, reaching a maximum thickness of 5500 m. In my undergraduate thesis, I target the local development of the...
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