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
Since 1998, a seismic network has been monitoring the underground gas storage located near the town of Příbram in the Central Bohemian Pluton, Czech Republic. Hundreds of weak induced seismic events have been recorded there. Moreover, several weak earthquakes have also been recorded from the vicinity of the nearby Orlík water reservoir. To improve location of both types of seismic events, shallow crustal structure of the region is studied in the present paper. Refraction measurements to distances of about 20 km were carried out using quarry blasts as seismic sources. Smoothed P-wave travel times were interpreted using the Wiechert-Herglotz method, which yielded a 1-D velocity model of shallow crustal structure down to a depth of about 1.7 km. The P-wave velocity of the model increases from about 5.0 km/s at the surface to about 6.15 km/s at the 1.7 km depth., Jiří Málek, Oldřich Novotný and Libor Žanda., and Obsahuje bibliografii
Among the programmes aimed at developing a standard model for properties and state of the Earth’s crystalline crust, those dealing with drilling the Kola (SG-3), Ural (SG-4) and German (KTB) superdeep boreholes yielded the most interesting results. No marked depth dependence of rock volume density and seismic wave velocities was observed in the sections of SG-3 and SG-4. A new result of the investigations is the discovery of strongly anisotropic rocks in the SG-3, SG-4 and KTB sections. In the massifs of the Kola and German superdeep boreholes such rocks constitute the majority of the drilled sections. The presence of the velocity anisotropy as well as the complex structure of the rocks composing crystalline metamorphosed sequences greatly hamper the interpretation of the results obtained from the seismic survey conducted at the surface., Felix F. Gobratsevich., and Obsahuje bibliografii
In our study we find, from the analysis of VLBI observations, small quasi-periodic fluctuations of the period and quality factor of retrograde Free Core Nutation (FCN), ranging mainly between 429.8 to 430.8 days and 17000 to 21000, respectively. To this end, we use resonant effects in several dominant forced nutation terms to calculate the period and quality factor of FCN in running 6-year intervals. We also recently demonstrated that the atmospheric and oceanic excitations are capable of exciting FCN. Both amplitude and phase of the geophysically excited motion are consistent with the values observed by VLBI, in the interval of tens of years. The geophysical excitations are now numerically integrated, using Brzeziński’s broadband Liouville equations, and removed from the observed celestial pole offsets. The remaining part is then used to derive the period and quality factor of FCN in running intervals, and to study the temporal stability of these important Earth parameters. It is demonstrated that the observed quasi-periodic variations of both parameters are probably not caused by these geophysical excitations., Jan Vondrák and Cyril Ron., and Obsahuje bibliografii
The results obtained by four years long TM 71 extensometer monitoring of 3D micro-tectonic displacements of Dinaric Fault Zone on two sites, being 260 m apart in Postojna Cave, were statistically evaluated with different methods (Kolmogorov- Smirnov test, comparison between relative displacement and earthquakes, linear regression, Kruskal-Wallis one-way analysis of variance, histograms and correlation coefficients). Responses to stress changes regarding x, y and z-axes are not the same on two monitoring sites even if we are monitoring the same fault zone. Kolmogorov-Smirnov test for comparing the two curves is applicable only for three axes combination (Postojna 1 z - Postojna 2 z, Postojna 2 y - Postojna 1 z, and Postojna 2 z - Postojna 2 y). Kruskal-Wallis analysis is most representative for z-axes. Some sharp peaks coincide with earthquake occurrences (Krn M=5.2, Cerkno M=4.0, Ilirska Bistrica M=3.9, Brežice M=2.9 and Krško M=3.1). Generally we detect very small tectonic deformations, dextral horizontal movement of 0.05 mm in 4 years for Postojna 1 and extension of 0.03 mm in 4 years for Postojna 2. Discrepancies between two sites can be attributed to complex geological structure and by the fact that studied fault zone is cut by cross-Dinaric fault zone., Stanka Šebela, Janez Turk, Janez Mulec, Blahoslav Košťák and Josef Stemberk., and Obsahuje bibliografii
To obtain the starting point for theoretical numerical computations the fibre reinforced concrete construction properties, adhesion of cement mixture with steel and polypropylene fibres and changes in its tension properties commensurate with number and weight percentage in the tested specimen were tested under laboratory conditions., Jiřina Trčková and Karel Řezba., and Obsahuje bibliografické odkazy
Evaluation of seismic loading in urban areas is not a simple process. The horizontal to vertical spectral ratio method technique has been often used for determination of site effect recently. Results from the re-interpretation of mining induced seismic events from Karviná region in frequency domain using archival databases will be presented in this study material. Also, spectra of continuous records (a bout two days) and evolution of spectra within a moving time window of the length 10 seconds are presented. These continuous records were registered on two places with different geological conditions., Zdeněk Kaláb and Alexey A. Lyubushin., and Obsahuje bibliografické odkazy
Generally, rock material failure is controlled by cracks under specific conditions. The study of rock fracture toughness belongs to the current frequent directions of research in the area of rock failure. The present paper describes the effects of parameters influencing the resultant properties of rock materials (bending rate, rock moisture) during fracture toughness measurement of different kinds of rocks (sandstone, marble, granite). The highest fracture toughness values were found in the marble samples. This is probably due to the inner structure of analysed marble, which is composed of only one mineral (calcite) and also has a lower porosity than the used granite. The lowest fracture toughness values were found in the sandstone sample, and reached c. 17-30 % of the measured fracture toughness values of the analysed granite and marble samples. As in the case of the other mechanical properties of rocks (e.g. uniaxial compressive strength) also in the case of higher sandstone (carboniferous) moisture the fracture toughness values decrease and its deformation ability increases. Preparation of samples for fracture toughness tests and performance of these tests are more complicated than in the case of tensile tests (e.g. the Brazilian test) and therefore this contribution presents a comparison between fracture toughness of analysed rocks and tensile strength values. The measured data in this study considering the fracture toughness tests and Brazilian tests were compared with results published by Zhang (2002)., Leona Vavro and Kamil Souček., and Obsahuje bibliografii
We analysed a nearly 133-km-long portion of the Sudetic Marginal Fault (SMF) in Poland (99.7 km) and the Czech Republic (33.8 km), comprised between Złotoryja in the NW and Jesenik in the SE. The fault trace has been subdivided into fifteen segments showing different orientation (N29°W to N56°W, and even N111°W SE of Złoty Stok), geological setting, length (8.8-22.9 km in Poland and 1.4-7.5 km in the Czech Republic), and height of the fault- and fault-line scarps (5-75 m to 200-360 m). Orientation of the entire fault trace approaches N41° W, and the mountain front sinuosity amounts to 1.051. Individual fault segments bear a flight of two to five tiers of triangular facets, showing differentiated state of preservation and degree of erosional remodelling. The highest triangular facets are confined to Rychlebské (Złote) and Sowie Mts. This tiering points to at least five episodes of uplift of the SMF footwall, starting shortly after 31 Ma, i.e. after basalts of the Sichów Hills area were displaced by the fault, and most probably postdating 7-5 Ma time interval, during which rapid cooling and exhumation of the Sowie Góry Mts. massif took place. Morphometric parameters of 244 small catchment areas of streams that dissect the fault scarp include, i.a. elongation, relief, and average slope of individual catchment areas, together with values of the valley flo or width to valley height ratios. These figures point to moderate tectonic activity of the SMF and allow us to conclude about Quaternary uplift, particularly important in the Sowie and Rychlebské (Złote) segments., Janusz Badura, Witold Zuchiewicz, Petra Štěpančiková, Bogusław Przybylski, Bernard Kontny and Stefan Cacoń., and Obsahuje bibliografické odkazy