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[en] Complete text of publication follows. A dense net of ten geodetic GPS reference stations in Austria, known with an extremely high precision, allows observations over Central Europe for small and medium scale ionospheric anomalies from station 'position errors' derived from carrier phase differences (L1-L2; using the Difference Doppler Effect). From the large number of individual observations over the past decade (2000 - 2009), ionospheric anomalies at F-region level are presented in form of coloured bi-hourly pixel maps (pixel: 0.5 degrees in latitude and longitude). On about 20% of the days, short lived regional anomalies (50.000 km2) not associated with 'space weather' are found, with a preference of occurrence during the winter months. There is a suggestion that these anomalies are associated with orographic effects (Alps), or unstable wind shears (Jet Stream), or at least due to forcing from below via atmospheric gravity waves. The occurrences of these ionospheric anomalies seem to depend not only on the sources but also on the 'atmospheric transparency' for the gravity waves.
[en] An earthquake catalogue of instrumental data for northeastern Italy since 1900 is presented. The different types of magnitude, which are the main parameters of the present study, have been evaluated so as to be as homogeneous as possible. Comparisons of the different magnitude values show linear dependence, at least in the medium magnitude range represented by the available data set. Correlations between the magnitude most significant for this region and chosen macroseismic data indicate a methodology for assessing the macroseismic magnitude of historical earthquakes which seems to be stable. (author)
[en] The complexity in earthquake occurrences has forced scientists to adopt an interdisciplinary approach for the development short-term forecasting model. In this manuscript, the authors have presented an interdisciplinary scheme involving pre-earthquake signals like geo-electrical measurements, relative humidity (RH) and outgoing longwave radiation (OLR). Prior to the occurrence of earthquakes, these parameters show exceptional deviation and indicate the nucleation of the earthquakes at the seismically active zones. Variations in the geo-electrical potential are observed prior to the occurrence of the earthquakes due to the physical and chemical interactions between hydrogen and Earth’s interior, which in turn facilitates the migration of the H+ ions through the interior of the earth. Also, this migration process weakens lithosphere, which produces non-synchronous stress variations along the fault interface. Due to the increased stress, the radioactive radon comes out from the voids of the rocks, ionizes the atmospheric air, which leads to the release of latent heat, and can be observed in the form of anomalous drop in RH and rise in OLR. Prior to the occurrence of Central Italy region earthquakes of the year 2016 (M > 6.0), the above-mentioned parameters have shown a significant variation than ± 2σ level. (author)
[en] The Umbria-Marche Apennines is a region characterized by strong historical and instrumental earthquakes located in a complex tectonic framework where both extensional and compressional activities are taken up. Moreover a particular fault structure, the Altotiberina fault (ATF), seems to play an active role within this tectonic extension, even if it is still not clear whether this structure is active or able to generate big earthquakes. Nevertheless which of the known fault systems play a major role in accommodating the extension, and which are the modes (seismic VS aseismic deformation) this extension is taken up, are still debated topics. Using a dense network of high-precision GPS measurements and a kinematic block modeling approach, this study evaluates which fault systems can better explain the crustal deformation observed by geodetic data. Inferring a tectonic activity of the ATF within this context, we evaluate its interseismic coupling distribution, and the resolution capability due to the spatial distribution of data. A wide portion of ATF, well resolved by data, is aseismically creeping, whereas for the first 4–5km of depth seems fully locked, providing new clues on its seismic potential.
[en] The Gravity Probe B (GP-B) experiment measured the geodetic precession due to parallel transport in a curved space-time metric, as predicted by de Sitter, Fokker, and Schiff. The Schiff treatment included Thomas precession and argued that it should be zero in a free fall orbit. We review the existing interpretations regarding the relation between the Thomas precession and the geodetic precession for a gyroscope in a free fall orbit. Schiff and Parker had contradictory views on the status of the Thomas precession in a free fall orbit, a contradiction that continues to exist in the literature. In the second part of this paper we derive the geodetic precession as a global Thomas precession by use of the equivalent principle and some elements of hyperbolic geometry, a derivation that allows the treatment of GP-B physics in between special and general relativity courses. (author)
[en] We present evidence of unusual Very Low Frequency (VLF) signal amplitude variation during the devastating earthquake of magnitude 9.0 which occurred at Honshu, in Japan on 11 March, 2011. We use the SoftPAL very low frequency receiver placed at Ionospheric and Earthquake Research Centre of Indian Centre for Space Physics, located at Sitapur (Lat. 22°30′N, Long. 87°47′E). We observe significant changes in signal amplitude from JJI (Lat. 32°05′N, Long. 131°51′E) station transmitting at a frequency of 22.2 kHz prior to the earthquake. We analyze signal amplitude for almost 2 weeks to establish a possible seismo-ionospheric correlation. We observe significant shift of the sunrise terminator time up to 2 days before the earthquake and the shift is found to be maximum on the day of the earthquake. In addition, we observe unusual increase of the D-layer disappearance time during the earthquake and the value becomes maximum on the day of the earthquake. These findings generally agree with our previous findings reported elsewhere. (author)
[en] The series of hydroelectric power plants on the Vakhsh River are the most important and responsible object for the sustainable development of Tajikistan located in the seismic active zone. At the first time the probabilistic seismic hazard assessment was made for this area with using the modern methods and techniques. This estimation based on the same geological and seismological data that existing seismic zoning map of the territory of Tajikistan. A set of maps of seismic impact estimation of this area was created in the values of the spectral accelerations for different return periods (145, 200, 475, 950, 5000 years). (author)
[en] The experimental research in Earth Physics has a tradition of over one century in Romania, the first seismological station and the first magnetic map of the country being the work of Stefan Hepites, member of the Romanian Academy. The creation of the Centre for Earth Physics and Seismology, in February 1977, brought together activities with a long tradition of development, but which, due to various administrative reorganizations, evolved separately after the dissolution, in 1970, of the Geophysical Research Centre of the Romanian Academy. In the Centre of Earth Physics and Seismology have been active, till the reorganization of the Romanian Academy in 1990, the Laboratory of Seismology, the research group on Crustal Structure, and the research group for Rock Mechanics, which formed the nucleus of the present National Institute of Earth Physics, as well as the Laboratory of Geodynamics and the research group for Natural Fields, which formed the nucleus of the present Institute of Geodynamics 'Sabba S. Stefanescu' of the Romanian Academy. The paper reviews the main scientific achievements in Geodynamics in the 25 years elapsed since February 1977, including facilities, equipment, and new research lines developed in the last years. (author)
[en] Earthquake - tremors, shocks and vibrations of the earth caused by natural processes in the earth's crust, which in its destructive action is similar to the action of a shock wave of a nuclear explosion. A plot of land from which derive the wave, called the center and a point situated above him on the earth's surface-the epicenter of the earthquake. Annually on Earth is about a million earthquakes, but most of them are so insignificant that they go unnoticed. In this article the author considers the restoration works, which are conducted after earthquakes arising in the cities of the Islamic Republic of Iran. Tremors in Iran happen literally every day. Development of high seismic resistance of residential and public buildings is the main goal of seismologists and town planners. (author)
[en] Complete text of publication follows. Detecting crustal movements using of the Global positioning system (GPS) has been applied at different seismically active Areas. Egypt is recognized as a moderate earthquake activity region with frequent moderate events. Most of its seismicity is concentrated northern Egypt and around Great Cairo. In order to monitor crustal deformation around Great Cairo, a local geodetic network consists of 8 geodetic points were established in 2004, around potential faults. Four campaigns were performed and processed using Bernese GPS software. The aim of this study is to determine the tectonic elements presented and spot light upon the geodynamic regime of the area. The magnetic results revealed that the main structural trends are NW and NNW. These trends indicate that Red Sea major fault systems have strong influence on the mechanism of rifting that control the present-day deformation. In addition to main Red Sea orientation, predominant NE (Dead Sea-Aqaba trend) and E-W (Tethyan trend) were prevailed. The velocity vectors for each epoch of observations were calculated and deformation analysis was performed. The horizontal velocity varies between 1 and 8 mm/year in average across the network. The results of the deformation analysis indicate significant contraction and extension across the southeastern part of the study area while, the southwestern part is characterized by an extension strain rates. Also, northeastern part is characterized by significant contraction. The tendency of increasing strain amount resulted from deformation analysis in some locations because of the stress accumulation considered as a precursory for certain earthquake events could be occurred in the study area.