The fault displacement monitoring network EU-TecNet was established to define microdisplacements across faults in the territory of Central Europe (www.tecnet.cz) using three-dimensional optical-mechanical extensometers. The results of long-term neotectonic activity obtained from two caves localized in the eastern part of the Slovenský kras Mts. (SE Slovakia) show generally NE-SW oriented dilatation. This orientation is in a good accordance with the orogen-parallel extension monitored in the Western Carpathians. Differing short-lasting trends were distinguished in 2011-2012 and 2013-2015, which supports the significance of the tectonic pulse at the end of 2012 and the beginning of 2013. Moreover, simultaneous short-lasting faulting occurred at both sites under the transtensional tectonic regime, where the principal maximum compressional axis operated in a NW-SE direction (σ1). The observed results were compared to data from monitoring points in distant areas of the European plate. and Briestenský Miloš, Hochmuth Zdenko, Littva Juraj, Hók Jozef, Dobrovič Roman, Stemberk Josef, Petro Ľubomír, Bella Pavel.
The paper presents results of epoch satellite GPS and gravimetric measurements performed on the geodynamic network in central part of the Stołowe Mts. between 1993 and 2009. The research results show significant changes of gravity on most of the points and significant horizontal movement of one point in the central part of the area. The results confirm present day activity of the zone where faults Polický, Bělský and Czerwona Woda Fault Zone exists. In addition, they correspond with the studies of seismic activity in this part of the Sudety Mts., Stefan Cacoń, Jan Kapłon, Bernard Kontny, Josef Weigel, Otakar Švábenský and Jiři Kopecký., and Obsahuje bibliografii
The combination method of results of different space geodetic techniques was recently improved and used to process approximately eight-year data obtained by three space geodetic techniques. The results are compared with the results obtained by the old approach of this method and finally with the solutions of ITRF 2005., Vojtěch Štefka., and Obsahuje bibliografii
Three year monitoring of micro-displacements on four tectonic fracture planes in a tunnel driven by a milling cutter into granitoids of Bohemian Massif revealed micro-movements that develop in certain trends and impulses. Two investigated fractures are of the Krušné Hory Mts. orientation (NE - SW), other two of Sudeten orientation (NW - SE). These have been found the two prevailing fracture orientations in the massif. Results from all the four fractures indicate trends in overfaulting of southern blocks over the northern ones and a stress state model characteristic of approximate N-S compression with overthrust vergence to N. Besides, some impulses were indicated with abrupt occurrence that dominates the development of movements. The first most significant impulse occurred by the end of the year 2004, the second one at the break of 2005/6. The coincidence of the impulses with earthquake events is discussed., Josef Stemberk and Blahoslav Košťák., and Obsahuje bibliografii
To investigate recent crustal movements between northern and southern parts of Moravo-Silesian region of the Bohemian Massif and to find their relation to movements of structure blocks of Moldanubicum, it was decided to establish a regional geodynamic network HIGHLANDS. Seven sites for monitoring GPS signals were built with respect of geological and geophysical materials in the southern area of the Českomoravská vysočina Highlands. So far two epoch 48-hours GPS measurements have been performed in 2005 and 2006 with Ashtech receivers and antennas. GPS monitored data were processed by the Bernese software v. 5.0. The rather preliminary site movements were assessed and discussed from the viewpoint of recent geodynamic motions., Zdeňka Schenková, Vladimír Schenk, František Mantlík and Milada Grácová., and Obsahuje bibliografické odkazy
The motion of Earth’s spin axis in space is monitored by Very Long-Baseline Interferometry (VLBI), and since 1994 also its rate is measured by Global Positioning System (GPS). From the direct analysis of the combined VLBI/GPS solution in the interval 1994.3-2004.6 we recently found that the apparent period of the Retrograde Free Core Nutation (RFCN) grew from original 435 days to 460 days during the past ten years, but the resonance effects yielded a stable period of about 430 days. Now we repeat the same study with VLBI-only data, covering much longer interval (1982.4 - 2005.6). Direct analysis shows again a substantial increase of the apparent period during the last decade or so. The resonant period is given by internal structure of the Earth (mainly by the flattening of the core), so it is highly improbable that it is so much variable. From the same observations we derive corrections of certain nutation terms. A subsequent study of indirect determination of resonance RFCN period from the observed forced nutation terms through the resonance effects proves that the natural resonance period remains stable and is equal to 430.32±0.07 solar days. From this follows that an excitation by outer layers of the Earth (atmospheric, oceanic) should exist, with a terrestrial frequency close to that of RFCN (of about -1.0050 cycles per solar day, i.e. with period of -23h53m mean solar time), invoking the apparent changes of the directly observed RFCN period. Thanks to a close proximity of the resonance, any excitation with this period is extremely amplified so that the excitation necessary to explain the difference can be very small. The atmosphere alone contains enough power to excite the observed changes., Jan Vondrák and Cyril Ron., and Obsahuje bibliografii
Ultrasonic velocity anisotropy in the rock provides information of variability of the dynamic elastic moduli. Young’s modulus and Poisson’s ratio calculated from waves velocities can be used to determine brittleness index, which is usually used to predict rock susceptibility for hydraulic fracturing. This paper describes laboratory ultrasonic measurements carried out in order to improve hydraulic fracturing designing. The research was conducted over two types of rock: shale and limestone. The samples were cut out perpendicularly and parallel to the bedding planes. Next they were tested for effective porosity and mineral composition using XRD method. Directionally depended seismic velocities revealed noticeable anisotropy of laminated shale, caused by orientation of the bedding planes and weak anisotropy of limestone. Based on the velocities, dynamic elastic moduli and its anisotropy coefficients were determined. Calculations of brittleness index based on Young’s modulus to Poisson’s ratio relation and three types of mineral composition brittleness indexes, revealed strong variability in brittleness for both kind of tested formations. These results show, that different types of brittleness indexes should be used complementary, to better describe fracability of the rock. and Moska Rafal, Kasza Piotr, Maslowski Mateusz.
Rock landforms in the Sokolský hřbet (ridge) and the adjacent Žulovská pahorkatina (hilly land) have been analysed through detailed field mapping at a scale of 1:10,000; subsequently the spatial distribution of these features was analysed using a DEM within a GIS framework. Particular attention was focused upon the shape of the rock landforms, their arrangement, the aspect of their walls, and their topographic position within the two adjacent geomorphological units. Rock landforms in the Sokolský hřbet include frost-riven cliffs, isolated residual rockforms, and blockfields in metamorphic rocks. In contrast, rock landforms in the Žulovská pahorkatina include rock steps and numerous tors exposed from the basal weathering surface. The Sokolský hřbet has been interpreted as a neotectonically uplifted mountainous region; the rock landforms described here are thought to have formed under periglacial conditions during cold periods in the Pleistocene, whilst the extensive granitoid block accumulations developed on marginal fault scarps are thought to result from the exposure of intensively disintegrated rocks due to uplift. Žulovská pahorkatina has been interpreted as a remodelled stripped etch surface, which has been twice glaciated during the Middle Pleistocene. The rock landforms in both units appear to be structurally and lithologically controlled; moreover, various shapes of granite rock landforms are controlled by various types of jointing and parting. The clear differences recognised in both the rock landforms and overall morphology reflects the considerable disparity associated with relief development between two adjacent morphostructural units; such variability provides evidence for a long polygenetic history within the entire study area., Petra Štěpančíková and Matt Rowberry., and Obsahuje bibliografii
Compact conical strain gauge probe for borehole over-coring rock massif stress measurement (CCBO), based on experiences of K. Sugavara and Y. Obara, has been developed in Institute of Geonics ASCR, v.v.i. from 2004. First generation of CCBO is equipped by simple electronic circuit which requires continuous communication with control computer in the course of measurement. Prototypes of this type probes are used for long term stress changes monitoring induced by longwall advancement in mine. Solving of continuous data communication through rotating drilling tool filled by wash water in course of over-coring is very difficult technical task, which is not possible to solve in terms of grant project. To avoid this problem a development of second generation of CCBO equipped by microprocessor and internal data logger was initialised. Simplified modification of CCBO is developed as a probe for long-term monitoring of rock massif stress changes (Compact Conical Ended Borehole Monitoring - CCBM). Design of both models probes, discussion of measurement errors and technique of sensitivity self-calibration is described., Jaromír Knejzlík, Zdeněk Rambouský, Kamil Souček and Lubomír Staš., and Obsahuje bibliografii
Bosnia’s seismotectonics seems to follow the Mediterranean marine regime. Earthquakes occur mostly in the outer Dinaric Alps (southern Bosnia), while the strongest earthquakes occur within the Sarajevo Fault system in southern and northwestern Bosnia. In addition to active tectonics being strong, crustal earthquakes occur often as well. Due to Bosnia’s rich hydrogeology, crustal loading such as by snow and rain, or reservoir inundation, represents the most important secondary seismogenic source in the region. Despite its exquisite and active geomorphology no comprehensive and reliable geodynamical studies exist on the region. Seismic sensors coverage is extremely poor also. One centenary analogue, and a few recently installed digital seismometers are insufficient for a region that exhibits mild-to-high seismic activity. Significant investments are needed in order for GPS, seismic and other sensor-instrumented networks to be put in place or enhanced. Technical personnel needs to be educated to enable support provide for studies that are done within broader scientific activities. Such efforts that presently seek to include Bosnia under their scope are ESF-COST Action 625, NATO Stability Pact DPPI program, and EUREF/CERGOP geophysics projects., Mensur Omerbashich and Galiba Sijarić., and Obsahuje bibliografii