Krypton and Xenon Radionuclides Monitoring in the Northwest Region of Russia     

Yuri V. Dubasov  Nikolay S. Okunev 《Pure and Applied Geophysics》2010,167(4-5):487-498

Monitoring of Xe and Kr radionuclides was conducted from August 2006 to 30 July 2008 within the framework of ISTC Project #2133. Cherepovets City in Vologda Province and St. Petersburg were chosen as monitoring locations. Kr–Xe concentrate samples were obtained as a result of processing of several thousand m³ of atmospheric air. New results of ⁸⁵Kr monitoring show, that for last 15 years, the ⁸⁵Kr volumetric activity in the atmospheric air of the northwest region of Russia has increased approximately 50% and has achieved a level of 1.5 Bq/m³. This value correlates well with similar data for Western Europe and Japan. The xenon fraction (80–160 cm³ under STP) is adsorbed on charcoal in the ampoule, which is measured in the well of HPGe gamma detector. Minimum detectable concentration (MDC) of ¹³³Xe for this technique is 0.008 mBq/m³, and it is the most sensitive method used today. The ¹³³Xe concentration in the atmospheric air of Cherepovets City varied in the monitoring period ranging from 0.09 to 2.5 mBq/m³. During the period of March 2007–30 July 2008, ¹³³Xe activity concentration in the atmospheric air of St. Petersburg changed from background values (0.2–0.3 mBq/m³) to 185 mBq/m³ and for approximately 20% of the samples ¹³⁵Xe was also measured with the ¹³⁵Xe/¹³³Xe activity ratio varied within the range of 0.03–3.5.  相似文献   

Neural network technique for identifying prognostic anomalies from low-frequency electromagnetic signals in the Kuril–Kamchatka region     

I. Popova  A. Rozhnoi  M. Solovieva  B. Levin  V. Chebrov 《Izvestiya Physics of the Solid Earth》2016,52(2):305-317

In this paper, we suggest a technique for forecasting seismic events based on the very low and low frequency (VLF and LF) signals in the 10 to 50 Hz band using the neural network approach, specifically, the error back-propagation method (EBPM). In this method, the solution of the problem has two main stages: training and recognition (forecasting). The training set is constructed from the combined data, including the amplitudes and phases of the VLF/LF signals measured in the monitoring of the Kuril-Kamchatka region and the corresponding parameters of regional seismicity. Training the neural network establishes the internal relationship between the characteristic changes in the VLF/LF signals a few days before a seismic event and the corresponding level of seismicity. The trained neural network is then applied in a prognostic mode for automated detection of the anomalous changes in the signal which are associated with seismic activity exceeding the assumed threshold level. By the example of several time intervals in 2004, 2005, 2006, and 2007, we demonstrate the efficiency of the neural network approach in the short-term forecasting of earthquakes with magnitudes starting from M ≥ 5.5 from the nighttime variations in the amplitudes and phases of the LF signals on one radio path. We also discuss the results of the simultaneous analysis of the VLF/LF data measured on two partially overlapping paths aimed at revealing the correlations between the nighttime variations in the amplitude of the signal and seismic activity.  相似文献   

Peculiarities of the within-year distribution of earthquakes in the Kuril region     

M. Yu. Andreeva  E. V. Sasorova  B. W. Levin 《Russian Journal of Pacific Geology》2009,3(5):491-500

Recent investigations have shown that the probability of the occurrence of earthquakes in a specified region depends on several factors, such as the latitude of the study region, as well as the lunar and solar tidal forces, which are governed by the mutual arrangement of bodies in the Sun-Earth-Moon system. The objective of our work is to prove that the irregularity of the within-year distribution of seismic events in the Pacific regions (the Kuril Islands and Hokkaido Island) is a statistically significant process, which is manifested in different ways for earthquakes with various source depths and energy levels. The hypothesis about the uniform within-year distribution of earthquakes is refuted for shallow events. However, it is shown that deep earthquakes are distributed uniformly. This work attempts for the first time to determine the stability degree of the within-year irregularity of seismic events with respect to the observation time interval (from 28 to 5 years). Two peaks are noted in the annual distribution of the earthquakes. The relation of the peaks of the within-year seismic activity to the Earth’s position on the ecliptic plane, as well as the relationships between the peaks, the magnitude range of the events, and the position of the specified subregion, is considered. The principal maximum of the seismic activity falls in the November-March period, which matches the minimum Earth-Sun distance.  相似文献   

The Kuril tsunamis of November 15, 2006, and January 13, 2007: Two trans-pacific events     

N. P. Laverov  L. I. Lobkovsky  B. W. Levin  A. B. Rabinovich  E. A. Kulikov  I. V. Fine  R. E. Thomson 《Doklady Earth Sciences》2009,426(1):658-664

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Identifying low-temperature hydrothermal karst and palaeowaters using stable isotopes: a case study from an alpine cave,Entrische Kirche,Austria     

Christoph Spötl  Yuri Dublyansky  Michael Meyer  Augusto Mangini 《International Journal of Earth Sciences》2009,98(3):665-676

The area south of the prominent east–west trending Salzach Valley at the northern rim of the Central Alps of Austria has long been known to host anomalously warm springs emerging from a highly deformed calcite marble (Klammkalk). This unit also hosts cavities whose shapes suggest a hydrothermal karst origin and which are lined by calcite spar. We report here petrographic and isotopic evidence suggesting that dissolution by ascending low-temperature thermal waters also played an important role in the origin of a large cave in this region, Entrische Kirche. A paleo cave wall, preserved behind a thick flowstone in the interior of this cave, revealed a brownish bleaching zone which contrasts to the medium grey colour of the unaltered marble beneath. Across this zone the C and O isotope values gradually decrease by 3 and 11‰, respectively. These compositions are very different from those of the speleothem above but are similar to phreatic calcite spar from hydrothermal karst cavities in other outcrops in the area, where the absence of two-phase fluid inclusions suggests a low-temperature (less than ca. 50°C) hydrothermal origin. U/Th dating of the flowstone capping the alteration zone yielded a minimum age of the thermal water invasion in Entrische Kirche of ca. 240 kyr. There is no evidence in Entrische Kirche that these palaeowaters reached the point of calcite precipitation, but it is physically conceivable that higher and as yet unexplored parts of this deep (ca. 900 m) cave contain cavities lined by phreatic cave spar.  相似文献   

On the influence of DC railway noise on variation data from Belsk and Lviv geomagnetic observatories     

Anne Neska  Jan Reda  Mariusz Neska  Yuri Sumaruk 《Acta Geophysica》2013,61(2):385-403

Geomagnetic variation data from the observatories in Belsk (BEL, Poland) and Lviv (LVV, Ukraine) significantly suffer from disturbances caused by direct current (DC) electric railways. The aim of this study is to quantify the impact of these disturbances on quantities derived from such data, as the K index of magnetic activity and the induction arrow used in the geomagnetic deep sounding method to indicate lateral contrasts of electric conductivity in the solid earth. Therefore, undisturbed data have been reconstructed by means of a frequency-domain transfer function that relates the horizontal magnetic field components of the observatory to the ones synchronously recorded at a noise-free reference station. The comparison of the K index derived from original and reconstructed data shows an increase of quiet time segments by 29% for LVV and by 14% for BEL due to our noise removal procedure. Furthermore, the distribution of the corrected K indices agrees well with the one from the Niemegk observatory in Germany.  相似文献   

Introduction     

William L. Bandy  Yuri Taran  Carlos Mortera Guti��rrez  Vladimir Kostoglodov 《Pure and Applied Geophysics》2011,168(8-9):1251-1253

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On the use of IPCC-class models to assess the impact of climate on Living Marine Resources     

Charles A. Stock  Michael A. Alexander  Nicholas A. Bond  Keith M. Brander  William W.L. Cheung  Enrique N. Curchitser  Thomas L. Delworth  John P. Dunne  Stephen M. Griffies  Melissa A. Haltuch  Jonathan A. Hare  Anne B. Hollowed  Patrick Lehodey  Simon A. Levin  Jason S. Link  Kenneth A. Rose  Ryan R. Rykaczewski  Jorge L. Sarmiento  Ronald J. Stouffer  Franklin B. Schwing  Francisco E. Werner 《Progress in Oceanography》2011,88(1-4):1-27

The study of climate impacts on Living Marine Resources (LMRs) has increased rapidly in recent years with the availability of climate model simulations contributed to the assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Collaboration between climate and LMR scientists and shared understanding of critical challenges for such applications are essential for developing robust projections of climate impacts on LMRs. This paper assesses present approaches for generating projections of climate impacts on LMRs using IPCC-class climate models, recommends practices that should be followed for these applications, and identifies priority developments that could improve current projections. Understanding of the climate system and its representation within climate models has progressed to a point where many climate model outputs can now be used effectively to make LMR projections. However, uncertainty in climate model projections (particularly biases and inter-model spread at regional to local scales), coarse climate model resolution, and the uncertainty and potential complexity of the mechanisms underlying the response of LMRs to climate limit the robustness and precision of LMR projections. A variety of techniques including the analysis of multi-model ensembles, bias corrections, and statistical and dynamical downscaling can ameliorate some limitations, though the assumptions underlying these approaches and the sensitivity of results to their application must be assessed for each application. Developments in LMR science that could improve current projections of climate impacts on LMRs include improved understanding of the multi-scale mechanisms that link climate and LMRs and better representations of these mechanisms within more holistic LMR models. These developments require a strong baseline of field and laboratory observations including long time series and measurements over the broad range of spatial and temporal scales over which LMRs and climate interact. Priority developments for IPCC-class climate models include improved model accuracy (particularly at regional and local scales), inter-annual to decadal-scale predictions, and the continued development of earth system models capable of simulating the evolution of both the physical climate system and biosphere. Efforts to address these issues should occur in parallel and be informed by the continued application of existing climate and LMR models.  相似文献   

Contribution of horizontal deformation of the seafloor into tsunami generation near the coast of Japan on March 11, 2011     

M. A. Nosov  S. V. Kolesov  B. W. Levin 《Doklady Earth Sciences》2011,441(1):1537-1542

Based on the USGS slip distribution data (Finite Fault Model), the vector field of the seafloor deformation in the source of the tsunami that occurred on March 11, 2011, was calculated. The field of seafloor deformation and distribution of depths in the area of the source were used for reconstruction of the initial elevation of the water surface in the tsunami source. It was found that the contribution of horizontal deformations into the amplitude of the initial elevation, into the displaced water volume, and into the potential energy of the initial elevation is at about 20–25%. Within the framework of the linear theory of long waves, numerical simulation of evolution of the initial elevation was made. The simulation results were compared to the signals recorded by the four deep water stations DART which were the nearest to the source. It was shown that account of the horizontal deformation of the seafloor provides a more precise coincidence between the model and real data. Insignificant differences in arrival times of the model and real signals were interpreted as manifestation of phase dispersion and finite duration for the seafloor deformation to form.  相似文献   

Integrated magnetobiochronology of the Pliocene–Pleistocene Miyazaki succession,southern Kyushu,southwest Japan: Implications for an Early Pleistocene hiatus and defining the base of the Gelasian (P/P boundary type section) in Japan     

Motoyoshi Oda  Shun Chiyonobu  Masayuki Torii  Takashi Otomo  Jumpei Morimoto  Yuri Satou  Hiroshi Ishikawa  Matsuaki Ashikawa  Osamu Tominaga 《Journal of Asian Earth Sciences》2011,40(1):84-97

An integrated magnetobiochronology of the Miyazaki Pliocene–Pleistocene succession in the Miyazaki area, southwest Japan, was established using planktic foraminiferal and calcareous nannofossil biostratigraphy together with paleomagnetic data. The upper Miyazaki succession in the northern Miyazaki region can be divided into the Takanabe, Hisamine (redefined), and Higoyashiki (new) Formations, in ascending order. A depositional hiatus between the Hisamine Formation and the Takanabe and/or older formations was also identified based on integrated magnetobiostratigraphy from five sections including the Nagatani River (NGT) section through the uppermost Miyazaki succession. The hiatus, herein called the Hisamine unconformity, is equivalent to the Kurotaki unconformity between the Miura and Kazusa groups of the Boso Peninsula in central Japan. The depositional hiatus recognised in the lower Pleistocene of Pacific coastal areas in southwestern and central Japan may have resulted from tectonic activity associated with a change in the subduction direction of the Philippine Sea plate, which commenced prior to ca. 2.2 Ma. The youngest unit just below the hiatus is the upper part of the Takanabe Formation in the NGT section. The NGT section represents the continuous Late Pliocene to earliest Pleistocene sequence including the Gauss/Matuyama boundary and is here proposed as the type section for the Pliocene/Pleistocene boundary in Japan, which the IUGS ratified as the base of the Gelasian in 2009.  相似文献