The Moravia territory has been the subject of geokinematic investigation within scope of several realized research projects and repeated GPS campaigns since 1992. The monitoring has been concentrated on all the Moravia region as well as on particular areas of interest concerning the eventual possible geodynamic changes (Králický Sněžník Massif, Diendorf-Čebín Tectonic Zone (DCTZ) and others). At present time all the territory is covered by several tenths of permanent and epoch GNSS stations. Long observation time series at permanent stations alone are not sufficient for delivering the regional velocity field of sufficient density. On the other hand, epoch stations are more densely spread but periods of repeated observations are less frequent and often the data processing is not homogeneous. In the paper the preliminary kinematic model is briefly described which gives for the first time the general view of movement tendencies at the region of Moravia. On base of long-term monitoring it shows that the Southern Moravia region is more active then it was supposed., Lubomil Pospíšil, Otakar Švábenský and Josef Weigel., and Obsahuje bibliografii
The GRACE satellites have provided gravity field solutions with approximately monthly resolution since April 2002. The monthly solutions enable investigations of the annual, semi-annual and secular mass variations, which mainly occur in a thin layer of the Earth’s surface. By the end of the GRACE science mission in 2017, the time span has increased to 15 years, making the possibility of determining longer-period variations feasible. First attempts to determine multi-annual variations, i.e. periods of some years but less than 10, are presented in this study. A combination of 3 different PSD estimation methods has been used for identifying the regions of multi-annual mass variations. As a result, 8 different areas have been found with significant multi-annual mass variations. The source of multi-annual mass variations in most detected regions can be identified as related to the ENSO cycle. and Kiss Annamária, Földváry Lóránt.
Three variants of geophysical excitations and seven different VLBI solutions of celestial pole offsets (CPO) are used to determine period and Q-factor of Free Core Nutation (FCN). Brzeziński’s broad-band Liouville equations (Brzeziński, 1994) are numerically integrated to derive geophysical effects in nutation in time domain. Possible effect of geomagnetic jerks (GMJ) is also considered. Best-fitting values of FCN parameters are estimated by least-squares fit to observed CPO, corrected for the differences between the FCN parameters used in IAU 2000 model of nutation and newly estimated ones; MHB transfer function is used to compute these corrections. It is demonstrated that different VLBI solutions lead to FCN parameters that agree on the level of their formal uncertainties, but different models of geophysical excitations change the results more significantly. Using GMJ excitations always brings improvement of the fit between integrated and observed CPO. The obtained results show that the best fit is achieved when only GMJ excitations are used. Our conclusion is that GMJ are very probably more important for exciting FCN than the atmosphere and oceans. Empirical Sun-synchronous correction, introduced in the present IAU 2000 nutation model, cannot be explained by diurnal atmospheric tidal effects., Jan Vondrák and Cyril Ron., and Obsahuje bibliografii
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.
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.
RNDr. Aleš Špičák, CSc. (*1955), vedoucí oddělení tektoniky a geodynamiky Geofyzikálního ústavu Akademie věd ČR, v. v. i., v r. 2014 získal cenu předsedy AV ČR za propagaci či popularizaci výzkumu (viz Živa 2014, 6: CL). Při této příležitosti bychom chtěli dát čtenářům Živy možnost nahlédnout i mimo obor biologie - formou rozhovoru a navazujícího článku přiblížit témata, kterými se zabývá. A. Špičák je naším předním odborníkem na zemětřesení v seismicky aktivních oblastech, zkoumá také souvislosti sopečné a zemětřesné činnosti. Vystudoval užitou geofyziku na Přírodovědecké fakultě UK v Praze, od r. 1986 je vědeckým pracovníkem GFÚ AV ČR, v letech 1998-2007 zde působil jako ředitel. Kromě organizování přednášek i dalších akcí pro veřejnost bývá hostem rozhlasových a televizních zpravodajství při výskytu zemětřesení a sopečných erupcí. and Jana Šrotová, Andrej Funk, Lucie Krouzová.