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Start Over Subject Geologie. Meteorologie. Klimatologie Date Unknown

402. Second generation of conical strain gauge probe for stress measurement in rock massif

Creator:
Jaromír Knejzlík, Rambouský, Zdeněk, Kamil Souček, and Staš, Lubomír
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, geodynamika, geodynamics, stress measurement, over-coring, 7, and 551
Language:
English
Description:
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
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

405. Seismic activity in West Bohemia from 2001 - 2006

Creator:
Nehybka, Vladimír and Tilšarová, Radka
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, seizmologie, zemětřesení, seismology, earthquake, Čechy západní (Česko), Vogtland (Německo), Nový Kostel (Česko), Vogtland (Germany), Bohemia, Western (Czechia), Nový Kostel (Czechia), earthquake swarm, microearthquake, en echelon, tectonic line, 7, and 551
Language:
English
Description:
This article is concerned with seismicity in the region of West Bohemia - Vogtland after the Nový Kostel swarm of 2000. Seismicity during the period 2001 - 2006 is weak, though with several clusters of earthquakes; although these do not meet the criteria for a seismic swarm, their groupi ng in time and spacing along a line give an impression of tectonic disturbances and their behaviour in a period between swarms., Vladimír Nehybka and Radka Tilšarová., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

406. Seismic events in the Orawa-Nowy Targ Basin, Western Carpathians, November 30, 2004 - December 2005

Creator:
Guterch, Barbara
Format:
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Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, zemětřesení, earthquake, macroseismic data, Orawa-Nowy Targ Basin, Pieniny Klippen Belt, series of earthquakes, 7, and 551
Language:
English
Description:
An earthquake of magnitude M = 4.4, macroseismic intensity Io = 7 in the EMS scale, followed by a long series of aftershocks occurred on November 30, 2004 in southern margin of the Orawa-Nowy Targ Basin, Western Carpathians. Macroseismic epicentral data were determined for the main earthquake and the strongest aftershocks. The foci were shallow, less than 5 km i.e., originated in the Podhale Flysch. An array of seismic stations located in this seismically active area is necessary for better recognizing of the ongoing tectonic process., Barbara Guterch., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

407. Seismic measurements on a rock massif surface at short distances

Creator:
Vilhelm, Jan, Rudajev, Vladimír, Roman Živor, and Lokajíček, Tomáš
Format:
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Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, seizmicita, seismicity, repeatability of measurement, velocity measurement, seismic source, seismic P- and S-waves, 7, and 551
Language:
English
Description:
Various geotechnical tasks require the knowledge of rock properties, e.g., of elastic moduli, fracture systems, inhomogeneities, etc. Seismic measurements usually provide these parameters. To describe the detailed properties of small rock volumes, it is necessary to use high-frequency signals and suitable registration systems. Seismic measurements are carried out directly on rock surfaces. Although the conditions, under which measuremen ts are carried out, seem to be simple and convenient, practical measurements themselves are often complicated. The various measuring systems, including seismic sources and seismic receivers used for different base lengths, are discussed in this paper. It was found that, for the repeatability of measurements, the fixing of the sensors with plaster plays most significant role. Repeatability of hammer blow as seismic source is adversely affected namely by signal amplitude triggering. Pencil lead breaking tests with lead 1 and 6 mm in diameter were found as suitable for testing of the hi gh-frequency measuring systems. Measuring directly on the rock massif surface is different compared to exploration seismic measurements. Due to absence of a low-velocity layer it necessary to use a special choice of mutual orientation of sources and receivers. Polarization analysis may be advantageous to identify the arrival of P and S seismic waves. It was also found that the rock massif behaves as a narrow frequency-b and pass filter. For exciting frequencies of 0.1 and 1 MHz the transmitted signal displayed the same frequency of 25 kHz at a distance of 1.1 m., Jan Vilhelm, Vladimír Rudajev, Roman Živor and Tomáš Lokajíček., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

408. Seismicity and 10-years recent crustal deformation studies at Aswan region, Egypt

Creator:
Abdel-Monem, Mohamed S., Mohamed, Haggag H., Saleh, Mohamed, and Abou-Aly, Nadia
Format:
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Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, seizmicita, GPS sítě, seismicity, GPS netwoks, Asuán (Egypt), Aswan (Egypt), recent crustal deformation, Aswan region, 7, and 551
Language:
English
Description:
Since 1982, several study programs were in itiated for monitoring seismicity, unde rground water behavior and recent crustal movements. The main characteristics of the seismic activity and the seismotectonics of the Aswan region are investigated based on the recently recorded seismic activity from 1982 to 2010 and the geodetic results. The results from these data sets are compared and combined in order to determine the main characteristics of deformation and hazard estimation in the Aswan region. GPS observations are being carried out by Aswan ge odetic network twice a year since 1997 and still until now. Analysis of the repeated 10-years GPS campaigns from the network revealed horizont al movements at the level of 7 - 10 mm/a. The estimated strain rate tensors show compression and tension components in the directions WNW-ESE and NNE- SSW which consistent with the P- and T-axes derived from ear thquake fault plane solutions, respectively. The network are a has been suffered from post-seismic deformation during the present interval; hence an increase in the general earthquake activity in the area could be expected., Mohamed S. Abdel-Monem, Haggag H. Mohamed, Mohamed Saleh and Nadia Abou-Aly., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

409. Seismicity and seismic hazard analysis in and around the proposed Tushka New City site, South Egypt

Creator:
Fat-Helbary, Raafat E., Khashab, Hussein M. El, Dojcinovski, Dragi, Faragawy, Karrar O. El, and Abdel-Motaal, Abdel-nasser M.
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, seizmicita, seismicity, Egypt, seismic hazard, proposed Tushka New City site, acceleration, Kalabsha, 7, and 551
Language:
English
Description:
For the last decade the Egyptian government has planned to implement the Tushka project at the southeastern part of the western Desert. This project includes the construction of a number of new cities. Tushka New City is one of these cities. Tushka area has a complex tectonic and geological history. Although no historical earthquakes are known to have occurred in the Tushka area, five large earthquakes of magnitude between 5.1 and 6.2 were recently observed from four active zones located around Tushka area. In addition to these four zones many microearthquakes have been detected in and around Tushak area. The main purpose of this research is to elucidate the seismicity and estimate the seismic hazard due to this activity in the study area. According to the spatial distribution of earthquakes that located in and around the study area, 9 seismic zones are defined on the seismotectonic map. For each seismic zone the seismic hazard parameters are estimated and used as input data for seismic hazard analysis. The resulting probability distributions are taken to produce iso-acceleration map for specific periods and economic life of public structures. The hazard at the proposed Tushka New City site is given by the hazard curve that is represented by the relationship between the peak ground acceleration and its annual exceedance probability. The maximum peak ground acceleration is 49, 137, 157 and 177 cm/s2 (gal) for zones Z-1, Z-6, Z-9 and Z-4 respectively. Although the values of PGA in zones Z-4, Z-6 and Z-9 are almost the same, Z-4 has a significant effect on the proposed Tushka New City site due to its location about 140 km northeast to the study area, while the calculated maximum acceleration with 90 percent probability of not being exceeded in 50 years of exposure time (475 years return period) at the proposed Tushka New City site was about 22 cm/s2., Raafat E. Fat-Helbary, Hussein M. El Khashab, Dragi Dojcinovski, Karrar O. El Faragawy and Abdel-nasser M. Abdel-Motaal., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

410. Seismicity, groundwater level variations and earth tides in the Hronov-Poříčí Fault Zone, Czech Republic

Creator:
Kolínský, Petr, Valenta, Jan, and Gaždová, Renata
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, seizmicita, tlak vzduchu, seismicity, air pressure, Eastern Bohemian Massif, groundwater level, earth tides, 7, and 551
Language:
English
Description:
Local seismicity of the Hronov-Poříčí Fault Zone is studied using two-year continuous seismic data from four seismic stations in the area. Newly developed software for automatic seismic events detection is introduced - it is based on the method used at the Icelandic seismic network. Twelve major local earthquakes are detected, localized and their magnitudes are estimated. Simultaneously, groundwater levels are continuously monitored in three wells in the area. Multiple-filtering method, originally used for processing of broadband and dispersed seismic signals, is modified and used for the frequency-time analysis of the water level data. Dominant tidal influence on the groundwater level variations is shown. Theoretical tidal potential for all three well locations is computed. Groundwater data and tidal potential are bandpass filtered to focus on the semidiurnal periods. Mutual amplitude ratio and phase shift between both quantities are computed. Each of the three wells exhibits different pattern of the groundwater level variations with respect to tides. A distinct change in the phase shift is observed at the VS-3 well in the second half of 2009. In the same time span, increased seismic activity is also observed. However, other two wells do not exhibit any evidence of such phase shift. Detailed groundwater level data analysis does not prove any significant rises or drops of the groundwater levels in 28 day intervals around the detected local events. In contras t, unexplained groundwater level drop in the V-34 well is obser ved 18 hours before the teleseismic Tohoku earthquake, Japan, March 11, 2011, Mw = 9.0., Petr Kolínský, Jan Valenta and Renata Gaždová., and Obsahuje bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public