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[en] Full text: Character of the spread of the plate-tectonic structures of Paleotethys and its oceanic basins including plan and age of the deformation as well as relation between Paleotethys and Mesotethys and the other issues are urgent debatable problems of the Paleozoic-Triassic geology in the region. As a result of complex geologic, magmatic, tectonic, paleo bio geographic, geophysical and cosmotectonic studies in the Caucasus, Zacaspian and Iran there were constructed geo dynamic maps on the paleo tectonic basis for certain time sections starting from the Cambrian transition stage till the Triassic models of Paleotethys evolution for two near-meridional geo traverses Arabian margin of Gondwana and in the north it crosses the East-European platform. In the Cambrian the change of the carbonaceous facies by the arkosicsandstones and quartzites in the Gondwana and in the East-European platforms is associated with the absolute elevation and washout of the Caspian-Caucasian shield. This is a precursor of more significant events and processes. There probably occurred a large structural reconstruction in the boundary of the Cambrian and the Ordovician associated with the beginning of the opening of the Caucasian, Turkestan and Ural pale oceans. As a result of the continental riftogenesis that in the next stage is transformed from the rifting into the spreading of the oceanic crust the double deep-water basins of Paleotethys were separated. The closure of neo-Paleotethys in the late Triassic was preceded by the crack of Gondwana and location of a system of the branching rifting and spreading of Mesotethys
[en] The Transantarctic Mountains provide a cryptic but important record of Proterozoic and Early Paleozoic supercontinent history, including Rodinian assembly, Rodinian breakup, transition from a drifting to subducting margin, and active plate-margin activity during Gondwanan assembly. A linkage between Laurentia and East Antarctica as part of Neoproterozoic Rodinia is plausible, based on isotopic data from rare exposures of crystalline basement in the Transantarctic Mountains. However, testing of paleogeographic details is difficult because the crustal structure of the East Antarctic shield is poorly known along much of its perimeter and because we lack well-dated Proterozoic paleomagnetic poles. The timing of Rodinian breakup is poorly constrained globally, yet local mafic magmatism of 800-650 Ma age provides the best evidence in the Transantarctic Mountains for Late Neoproterozoic crustal extension and possible rifting. Still uncertain are the position of the rift margin, the geometry of rifting, the extent of crustal thinning, the extent of rift-margin sedimentation, the location of possible transform offset, and the influence of these structural patterns on later orogenesis. A transformation from drifting to active subducting mode is inferred for the Late Neoproterozoic, but the nature and specific timing of this event are unknown. The Vendian-Early Paleozoic Ross Orogen reflects convergent-margin activity associated temporally, if not causally, with the consolidation of Gondwana. Inception of a convergent Gondwana margin is signalled by the earliest Ross granitoids at c. 560 Ma and may be reflected in early structural inversion of craton-margin sedimentary succession. Protracted Ross tectonism between 560 and 480 Ma involved episodic deformation, calc-alkaline magmatism, and syn-orogenic deposition of arc-derived detritus in a sinistral-transpressive, continental-margin arc setting. Sedimentary provenance in siliciclastic rocks appears to have shifted by late Early Cambrian time from cratonic to chiefly arc-derived material. Diachronous Ross magmatism and deformation may reflect progressive, hinged opening of paleo-Pacific seafloor from north to south (present-day co-ordinates) between Laurentia and East Antarctica-Australia. (author). 104 refs., 6 figs
[en] Complete text of publication follows. The PICASSO (Project to Investigate Convective Alboran Sea System Overturn) project is an international, multi-disciplinary project that aims to improve knowledge of the internal structure and plate-tectonic processes in the highly complex three-dimensional region formed by the collision of the African and European plate under the effect of the Mediterranean plate motion. The first phase of the DIAS magnetotelluric (MT) component of PICASSO was carried out in Southern Spain from Sept.-Nov., 2007. Two different types of magnetotelluric (MT) equipment - Phoenix V5 broadband (BBMT) and Lviv LEMI long period (LMT) - were used along a profile from the outskirts of Madrid to the Mediterranean Sea across the Betic Mountain Chain. In spite of low solar activity during acquisition and the high noise due to DC train lines etc., the time series data are of reasonable to good quality at most sites due to the excellent instrumentation and careful site location. The modified acquisition design of the LEMI long period system facilitated separate recording of each telluric channel independently, which allowed for advanced investigation of the dataset. The data were processed using four different robust algorithms, and the different responses have been compared. Strike direction varies along the profile and with depth due to the intricate morphology, and its choice has an enormous impact on the responses to be modelled and thereby provides a challenging framework for MT data interpretation. Preliminary models derived from the distortion-corrected data show features in the Betics similar to previous studies. Rather surprisingly, to the north the central part of Spain exhibits a highly resistive lower crust. Other model features will be discussed.
[en] The main geophysical conceptions regarding the tectonic seismicity of the Vrancea region are presented, with emphasis on great historical earthquakes as recorded by the Romanian Earthquake Catalogue. Their geographical and in-depth distribution is also presented, as well as their main characteristics. The post-seismic regime of two main events in Vrancea (August 1986 and May 1990) is analyzed, and Omori exponents are derived for the aftershocks distribution. One exponent agrees qualitatively with the usual range of exponents (0.8 with respect to 1), while the other exponent seems to be outside this range (0.3), possibly due to an imperfect definition of the genuine aftershocks. (authors)
[en] The temporal seismicity change in two seismically active zones around Hokkaido, northern Japan was investigated using the statistical estimate of the seismicity level (SESL’09) procedure. Hypocenter data provided by the Japan Meteorological Agency from 1960 to 2013 were analyzed. The seismicity of two geographically different zones, formed by Pacific Plate subduction and Amurian Plate convergence, showed different statistical characteristics. Low cross-correlation values between the two zones also suggest independent seismic processes for each area. However, an anomalously high cross-correlation period was identified from 1996 to 2000, with a time lag of 8 weeks. A 6-month seismic quiescence period before the strongest Hokkaido Toho-Oki Earthquake (4 October 1994, Mj 8.2) was observed on the Pacific side.
[en] Sunspots are the most notable structure on the solar surface with strong magnetic fields. The field is generally strongest in a dark area (umbra), but sometimes stronger fields are found in non-dark regions, such as a penumbra and a light bridge. The formation mechanism of such strong fields outside umbrae is still puzzling. Here we report clear evidence of the magnetic field of 6250 G, which is the strongest field among Stokes I profiles with clear Zeeman splitting ever observed on the Sun. The field was almost parallel to the solar surface and located in a bright region sandwiched by two opposite-polarity umbrae. Using a time series of spectral data sets, we discuss the formation process of the super-strong field and suggest that this strong field region was generated as a result of compression of one umbra pushed by the horizontal flow from the other umbra, such as the subduction of the Earth’s crust in plate tectonics.
[en] Six hundreds and eighty earthquakes causing significant damage have been recorded since the 7. century in Japan. It is important to recognize faults that will or are expected to be active in future in order to help reduce earthquake damage, estimate earthquake damage insurance and siting of nuclear facilities. Such faults are called 'active faults' in Japan, the definition of which is a fault that has moved intermittently for at least several hundred thousand years and is expected to continue to do so in future. Scientific research of active faults has been ongoing since the 1930's. Many results indicated that major earthquakes and fault movements in shallow crustal regions in Japan occurred repeatedly at existing active fault zones during the past. After the 1995 Southern Hyogo Prefecture Earthquake, 98 active fault zones were selected for fundamental survey, with the purpose of efficiently conducting an active fault survey in 'Plans for Fundamental Seismic Survey and Observation' by the headquarters for earthquake research promotion, which was attached to the Prime Minister's office of Japan. Forty two administrative divisions for earthquake disaster prevention have investigated the distribution and history of fault activity of 80 active fault zones. Although earthquake prediction is difficult, the behaviour of major active faults in Japan is being recognised. Japan Nuclear Cycle Development Institute (JNC) submitted a report titled 'H12: Project to Establish the. Scientific and Technical Basis for HLW Disposal in Japan' to the Atomic Energy Commission (AEC) of Japan for official review W. The Guidelines, which were defined by AEC, require the H12 Project to confirm the basic technical feasibility of safe HLW disposal in Japan. In this report the important issues relating to fault activity were described that are to understand the characteristics of current fault movements and the spatial extent and magnitude of the effects caused by these movements, and to estimate the spatial extent of future fault movements and their effects on the geological environment. One conclusion from the report is that present active faults in Japan have moved repeatedly for at least the last several hundred thousand years and are likely to continue to do so under the same stress field in the next a hundred thousand years. The latest knowledge relating to active faults and features of active faults to be considered for the stability of geological environments are described. (author)