a2_The town of Litija was hit by four damaging earthquakes in the last 120 years which reached a maximum intensity of VII-VIII MSK. The town is located in a shallow sedimentary basin filled with relatively soft Quaternary sediments in which seismic site amplification is expected. On the other hand no borehole or geophysical data are available to support quantitative assessment of site effects. As a contribution to the first seismic microzonation of the area, we performed a free-field study based on the microtremor HVSR method in order to assess the resonance frequency of th e sediments. In ge neral clear spectral peaks were obtained for 57 measuring points which show distribution of frequencies in a broad range between 4.4 an d 22.7 Hz. The iso-frequency map was prepared by using natural neighbour interpolation algorithm. For soil-structure resonance assessment we considered large building stock from different Slovenian towns, because the building typology is similar in wider area. Low-rise masonry family houses with two or three floors prev ail. By microtremor measurements inside 45 such buildings their fundamental longitudinal and transver se frequencies were determined and statistically analysed in a complementary study. To assess the possible occurrence of soil-structure resonance in general, the average fundamental frequency +/- one standard devia tion interval is obtained for these two building heights, which give s the range 5.6-11.1 Hz. The free-field microtremor data shows that this frequency range occupies 37% of the urban area in the Litija basin. This study has shown that soil-structure resonance issue for low-rise buildings is frequently overlooked, but should be considere d seriously in shallow sedimentary basins, characterized by relatively high free-field frequencies, because many towns are located in such geological environment., a2_Second application of the derived iso-frequency map is to support soil classification, because recent investigations have shown that fundamental frequency of sediments can be used together with the average shear velocity in the upper 30 m to improve classi fications according to di fferent seismic codes., Andrej Gosar., and Obsahuje bibliografické odkazy
Correlation of boreholes and geophysical data provides the framework for 3D modelling of the crystalline basement and the Permo-Carboniferous volcano-sedimentary strata in the Mnichovo Hradiště Basin. The knowledge of depth of the individual interfaces acquired from boreholes database and interpretation of the seismic profiles enabled construction of 3D models. The Stráž crystalline block has bounded the Mnichovo Hradiště Basin on the north, its elongation is in NNW-SSE direction and maximal depth has reached near Sobotka. Its second deepest part known as Mcely or Sukorady sub-basin has been detected southeast of Mladá Boleslav. The negative gravity anomaly in the Mimoň- Český Dub- Turnov- Mnichovo Hradiště area indicated presence of „light“ granitic rocks in the crystalline complex. Moreover, the highest volume of rhyolite ignimbrites with a thickness of up to 180 m is concentrated in Permo-Carboniferous volcano-sedimentary strata in this negative gravity anomaly area, which can be related to a rather deep Late Paleozoic volcanic source (up to a depth of about 10 km)., Zuzana Skácelová, Bedřich Mlčoch and Zuzana Tasáryová., and Obsahuje bibliografii
Microseismic monitoring has become a standard technique to map the development of hydraulic fracturing. This study is a case study of a downhole monitoring of the hydraulic fracturing in a lateral well in Northern Poland. The downhole monitoring array detected a large number of microseismic events indicating successful development of a hydraulic fracture. We show evidence that some stages interacted with the pre-existing natural fault system also mapped from surface active seismic imaging. The mapped hydraulic fracture shows a slight asymme try of the developed hydraulic fractures. We show that the observed microseismicity is cons istent with microseismicity usually observed in the North American shale gas stimulations., Eryk Święch, Paweł Wandycz, Leo Eisner, Andrzej Pasternacki and Tomasz Maćkowski., and Obsahuje bibliografické odkazy
We study the efficiency of individual stations of the CRL seismic network in recording the seismic activity in the western Gulf of Corinth, Greece. The stations are located on both the northern and southern coast of the Gulf. The study is based on 5027 earthquakes recorded in 2001, separated into three groups, the southern, central and the northern one. The events were located using the HYPO71PC algorithm. It is shown that the stations significantly differ in their monitoring ability., Jaromír Janský, Jiří Zahradník and Vladimír Plicka., and Obsahuje bibliografii
Formulas for full seismic moment tensor composition are present, i.e. moment tensor is express as a function of ISO, CLVD, DC, strike, dip, rake, where ISO is amount of isotropic part, CLVD is amount of compensated liner-vector dipole and DC is amount of pure double couple. Two forms of final formulas are given: i, two matrixes multiplication, ii, extension of "classical" formulas for 6 independent moment tensor elements., Petr Kolář., and Obsahuje bibliografické odkazy
Russian electrodynamic seismometer named S-5-S is adaptable for measurement of rotational ground motion. In this paper brief information about mentioned adaptation is presented. Initial results from experimental m easurement in Karviná region in 2011 with high mining induced seismicity are documented. Measured values for the horizontal component reached up to 1 mrad s-1 , while the seismic energy of these events did not exceed the value of 10 5 J and hypocentral distances were within 2 km., Zdeněk Kaláb and Jaromír Knejzlík., and Obsahuje bibliografické odkazy
Two seismic sources were tested on different surfaces during acquisition of a 5.5-km long high resolution seismic reflection (HRS) profile on the Ljubljana Moor in central Slovenia. Maximum target depth range of the survey was 200 - 300 m. Nine different combinations of source-surface conditions were analysed. Seismic sources included a seismic shotgun and an accelerated weight dropper system. The HRS profile crossed different surfaces including: paved roads, gravel roads, ploughed fields, grasslands and marshlands. Seismic source performance on different surfaces was evaluated through frequency and S/N ratio analyses of seismic data, and analysis of source-generated coherent noise appearance on seismograms. Results show that both seismic sources are suitable for some of the surfaces found in the surveyed area. The accelerated weight dropper produced the best results on gravel road surface, but poor results were found on grassland and ploughed fields. The seismic shotgun produced the best results in water-saturated soil on marshlands. It performed less favourably in unsaturated soil, generating more coherent noise. Water-saturated marshland surface and gravel road surfaces were found to be the most favourable for acquisition of high-resolution seismic reflection data on the Ljubljana Moor., Jure Atanackov and Andrej Gosar., and Obsahuje bibliografii
The western part of the Bohemian Massif (Vogtland/West-Bohemia region at the Czech-German border) is characterized by relatively frequent intraplate earthquake swarms and by other manifestations of current geodynamic activity, such as mofettes, mineral and thermal springs. In this study we analyze variations of groundwater level in four hydrological wells in the region during the years 2005-2010. Monitoring during the previous time interval of 2000-2004 is also mentioned and used for comparison. Two of the wells are located in the epicentral region of Nový Kostel, and the other wells are more distant. The time interval includes the 2008 earthquake swarm when all the wells displayed a noticeable drop in the water level. This effect was observed up to epicentral distances of nearly 30 km, which exceeds the distances of hydrological changes observed during previous earthquake swarms. Moreover, it seems that a small rise in the water level preceded the intervals of increased seismic activity, which could represent a certain precursory phenomenon. On the other hand, the hydrological changes in the Nový Kostel area were relatively small, indicating that this epicentral area is not hydrologically linked with the seismically active fault at depth. Consequently, more suitable localities for hydrological monitoring should be sought in a broader vicinity of Nový Kostel., Renata Gaždová, Oldřich Novotný, Jiří Málek, Jan Valenta, Milan Brož and Petr Kolínský., and Obsahuje bibliografii
Non-liner inversion of ratio of (relative) P to S waves amplitudes of 3 selected KTB events was performed in Kolář (2007a) to determine moment tensors (MTs). Here further development of the method is presented: (i) re-calibration of the seismograms, (ii) re-interpretation of the S wave maximal amplitudes readings, (iii) a linear inversion of the (re-calibrated) amplitudes including MTs errors determination, and (iv) four methods of transformation of MT errors into errors of their decomposed parts. Generally, the new results confirm previous ones, however remain some open questions about MT errors transformation. New methodology is more accura te and data processing more user-friendly., Petr Kolář., and Obsahuje bibliografické odkazy
In October 2005 local seismic monitoring started in the area of the Hronov-Poříčí Fault Zone. In the present paper we summarize seismic measurements using a small-aperture seismic array Ostaš. Parameters of the array and methodology of the data registration and processing are described. The list of local microearthquakes during two years of registration is presented., Jiří Málek, Milan Brož, Vladimír Stejskal and Jaroslav Štrunc., and Obsahuje bibliografické odkazy