Quaternary faulting in the western part of the Gulf of Corinth has been evidenced by geology and geomorphology, as well as by seismic recording. A series of three main normal fault segments are aligned in a steep southern coastal zone of the gulf. These fault segments, 15 to 25 km long, have an average strike of 90° - 105° and a northward dip of about 50° - 75°. Selected fault points were equipped with 3-D crack gauges TM71 during 2002 to monitor movements along the fault planes here, as well as on another fault cutting through the small island of Trizonia near the opposite northern shore of the gulf. Results of the monitoring present relative displacements induced by active tectonic movement s. Generally, the movements recorded on the faults are characteristic of an aseismic linear creep in vertical, i.e. upliftin g/subsiding in rates of mm per year due to uplifts of the Peloponnesian Peninsula. In 2003 a thr ee months long period of fast acceleration of movements was recorded. During this acceleration phase displacements changed to skew uplifting/subsiding with a left-lateral horizontal component. Moreover, horizontal rotation of monitored blocks corresponding to a sy stematic westwards opening of the Gulf was observed with only single eastward opening episodes., Josef Stemberk and Blahoslav Košťák., and Obsahuje bibliografické odkazy
This paper examines the results of fault microdisplacement analyses obtained from sites located both at the surface and underground in western Slovakia. The results of surface monitoring showed significant annual climatic effects on the various displacement components. In contrast, the results of underground monitoring in caves showed minimal climatic effects. It is seen that the influence of climate decreases markedly with depth. The yearly peak-to-peak amplitude of climatic variations may be as high as 1 mm at the surface but only 0.1 mm underground. The amount of tectonic displacement can be determined once such climatic considerations have been taken into account. Our fault displacement measurements show horizontal strike-slip rates of tenths of mm or hundredths of mm per year. In addition, vertical displacements have been recorded at Prekážka Quarry, Driny Cave, and Slopy Cave. The network is sufficiently dense to identify changes in displacement activity recorded during recent, significant, earthquake events. Furthermore, three gauges have also helped to determine the local stress orientation in Driny Cave., Miloš Briestenský, Blahoslav Košťák, Josef Stemberk, Ľubomír Petro, Jozef Vozár and Lucia Fojtíková., and Obsahuje bibliografii
The paper presents the results of monitoring study undertaken during the period 2008 - 2010. The study recorded the displacement of tectonic structures in the Strašín Cave (SW Bohemian Massif). The derived results were compared, among others, with data recorded over the same time period across the Bohemian Massif in the EUTecNet (tectonic displacement monitoring net - see www.tecnet.cz), which is managed by IRSM ASCR. The rate of recorded displacement is mostly in order of hundredths mm/year with maximal value recorded in vertical component at site Strašín 2, about 0,16 mm/2,5 years. Whilst recorded displacement can indicate blocks subsidence into the cave empty space, the periods when displacement occurred correspond to periods of increased movement activity recorded for example at the opposite side of the Bohemian Massif, along the Sudetic Marginal Fault. Moreover, both periods are simultaneous with extraordinary earthquakes that affected western and southern part of the Bohemian Massif in 2008 and 2009., Josef Stemberk and Filip Hartvich., and Obsahuje bibliografii
Long-term geotechnical monitoring of crack and fissure movements in slope deformations, historical buildings, as well as underground objects in Slovakia, provided results that bear evidence of movement trends, as well as of present tectonic unrest. The results were subject to an analysis regarding anomalies in movements that would verify activity of a specific geodynamic process. Such a process was detected recently in the Bohemian Massif and evidenced even in other European countries, north as well as south of the Alps. The process began by a tectonic pressure pulse and followed by a phase of increased geotectonic activity. The search for signs identifying this process on the Slovak territory which belongs to a different geological unit than the Bohemian Massif was successful. This is further evidence that the process in question is of a very deep foundation. The investigations proved successful long-term outdoor operation of TM71 crack gauges working on the principal of mechanical interference between optical grids. A thirty year long record was even reached. A useful function of the gauge which allows for supplementary data about angular deviations in faults has been found useful in the analysis. The data indicate affinity of the process to a large global disturbance in the Earth crust., Ľubomír Petro, Blahoslav Košťák, Josef Stemberk and Ján Vlčko., and Obsahuje bibliografii
In this paper, results from the long-term monitoring of two deep-seated slope deformations are presented. These deformations are considered typical of the types of landslide that occur in the high mountains of the Western Carpathians. The localities are situated in similar geological settings and this has enabled direct comparison of their development over the past 30 years. The monitoring has been undertaken using the extensometric gauges, TM71. At the Parohy Site, results from the scarp area show a significant vertical displacement trend of 0.07 mm per year. At the Štrochy Site, results from the crown area show a horizontal crack opening trend of 0.015 mm per year. Monitoring is ongoing at both sites., Miloš Briestenský, Blahoslav Košťák, Josef Stemberk and Jozef Vozár., and Obsahuje bibliografii
Monitoring of tectonic movements along three active faults of Dinaric (NW-SE trending) fault system in W Slovenia using TM 71 extensiometers was set up in 2004. After two and a half years of measurements clear trends of displacement were recorded. The average left-lateral displacement along a crack in the inner fault zone of the Idrija fault in Učja valley was reading 0.38 mm/year. Short term (10 months) rates were even greater and reached the value of 0.54 mm/year. Since the Idrija fault is considered generally to be dextral strike-slipping, the observed left-lateral displacement can be explained by variations in principle stress. Raša fault monitoring site at the foot of Vremščica Mt. established an average reverse uplift of hanging wall (SW) block of 0.24 mm/year and left-lateral displacement of 0.16 mm/year. Short term (9 months) vertical displacements reached the value of 0.53 mm/year. The inclined displacement is in agreement with geological and seismological observations. In the Postojna cave system two instruments were installed at the fault which extends parallely to Predjama fault zone. The average vertical displacement rate at Postojna 1 site was 0.01 mm/year. Both devices recorded similar reaction which can be attributed to 12 July, 2004 (Mw=5.2) earthquake with an epicentre 70 km away from the measuring site. Since there were no other stronger earthquakes in the vicinity and time span of monitoring, no other correlations were established with earthquake activity. The observed displacement rates along all three monitored faults of up to 0.5 mm/year are consistent with the regional deformation rate in W Slovenia established from GPS measurements which is of the order of 2 mm/year., Andrej Gosar, Stanka Šebela, Blahoslav Košťák and Josef Stemberk., and Obsahuje bibliografii
At the end of 2010 seven TM 71 extensometers, installed at or near the active faults in Slovenia, were in operation. Three of them are on the surface and four inside karst caves. The highest rates with stable sense of movements were observed on the Idrija fault. Average horizontal displacement rate was 0.24 mm/year. Short term rates were even greater and reached 0.54 mm/year. The Raša fault first experienced an uplift of the SW block of 0.16 mm/year, which was followed by a short-term down-slip of the same block at the rate of 0.37 mm/year. Later the sense of movement returned to uplift with a rate of 0.05 mm/year. The average horizontal displacement was 0.07 mm/year. The Kneža fault experienced very small average displacements (y=0.035 mm/year, z=0.03 mm/year and x=0.02 mm/year). Similar rates were observed in nearby Polog cave (y=0.015 mm/year, z=0.027 mm/year and x=0.016 mm/year), which is located close to the seismically active Ravne fault. For Kostanjevica cave, located near the Brežice fault, small average rates are characteristic (y=0.006 mm/year, z=0.017 mm/year and x=0.012 mm/year). In Postojna cave, located close to the Predjama fault, two monitoring sites are very stable with small tectonic movements, including general dextral horizontal movement of 0.05 mm from 2004 to 2010 (Postojna 1) and two significant short-term peaks of 0.08 mm (Postojna 1-y and Postojna 2-z)., Andrej Gosar, Stanka Šebela, Blahoslav Košťák and Josef Stemberk., and Obsahuje bibliografii
Micro-displacement monitoring in Slopy a nd Zbojnícka caves is described. It st arted at the end of 2005 with the use o f verified, stable and sensitive 3D crack gauges TM71 produced by GESTRA Sedloňov. Two gauges were installed in the caves across significant tectonic structures. Registered displacements are pertinent to the last significant earthquake events. The f irst one appeared in March 13, 2006 at Vrbové, M=3.2; and later in August 5-8, 2006, a swarm of 10 quakes M max = 2.2 at Trstín was registered. The results indicated trends of dextral strike-slip displacements across observed fault structures in both of those caves., Miloš Briestenský and Josef Stemberk., and Obsahuje bibliografické odkazy
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
Stability conditions in a wider surrounding of the rock castle Drábské Světničky (Drábské Rooms) near the town of Mnichovo Hradiště were investigated. The area which has been intensively disturbed by large old as well as present slope movements is located in the north-western part of Příhrazy Platform. Solid, thick bedded sandstones, well resistant to weathering, are lying on claystones apt to plastic deformations. Marginal sandstone blocks separate, move down on the slope and sink into the plastic bedrock. As a result, block fields with many crevasses develop. In rock walls that separate individual blocks, rockfalls originate and central, as well as lower parts of the slopes develop large landslides. A zone comprising up to 400 m wide rim of the high and exposed platform has been subject to a process of loosening. A local group of tower-like sandstone blocks was used in the 15th century to build a small rock castle called Drábské Světničky. An extensive landslide that destroyed a substantial part of the village of Dneboh in June 1926, reached in its separating zone up to the toe of marginal rock towers belonging to the complex of Drábské Sv ě tni č ky with the result of local movement activation. Marginal zones of the flat land behind display fresh linear, as well as oval depressions and sinks. Fissure and pseudocarst caves develop. Present activity of the movements has been evidenced by dilatometric measurements on two selected rock objects where movement rates reached 1 to 2 mm per year in average., Jan Rybář, Josef Stemberk and Filip Hartvich., and Obsahuje bibliografické odkazy