Early Pleistocene magmatism in the central part of the Greater Caucasus

An isotope-geochronological study of young magmatism in the central part of the Greater Caucasus (Kazbek neovolcanic area) on the territory of Russia and Georgia has been carried out. It was proved for the first time that, in the Early Pleistocene, there was a separate impulse of magmatic activity in this area. The area of endogenic activity for the period identified was contoured on the basis of the integrated isotope-geochronological, petrological-geochemical, and geological data. It has been shown that the Early Pleistocene volcanism inherits the area of Neogene volcanism in the Kazbek region and, therefore, presents the final impulse of the second (Pliocene) stage of the Late Cenozoic magmatism. Thus, Early Pleistocene volcanism was not a precursor of Late Quaternary magmatism as the latter has other spatial patterns of the location of volcanic centers.     

Environmental Radioxenon Levels in Europe: a Comprehensive Overview

Activity concentration data from ambient radioxenon measurements in ground level air, which were carried out in Europe in the framework of the International Noble Gas Experiment (INGE) in support of the development and build-up of a radioxenon monitoring network for the Comprehensive Nuclear-Test-Ban Treaty verification regime are presented and discussed. Six measurement stations provided data from 5 years of measurements performed between 2003 and 2008: Longyearbyen (Spitsbergen, Norway), Stockholm (Sweden), Dubna (Russian Federation), Schauinsland Mountain (Germany), Bruyères-le-Châtel and Marseille (both France). The noble gas systems used within the INGE are designed to continuously measure low concentrations of the four radioxenon isotopes which are most relevant for detection of nuclear explosions: ^131mXe, ^133mXe, ¹³³Xe and ¹³⁵Xe with a time resolution less than or equal to 24 h and a minimum detectable concentration of ¹³³Xe less than 1 mBq/m³. This European cluster of six stations is particularly interesting because it is highly influenced by a high density of nuclear power reactors and some radiopharmaceutical production facilities. The activity concentrations at the European INGE stations are studied to characterise the influence of civilian releases, to be able to distinguish them from possible nuclear explosions. It was found that the mean activity concentration of the most frequently detected isotope, ¹³³Xe, was 5–20 mBq/m³ within Central Europe where most nuclear installations are situated (Bruyères-le-Châtel and Schauinsland), 1.4–2.4 mBq/m³ just outside that region (Stockholm, Dubna and Marseille) and 0.2 mBq/m³ in the remote polar station of Spitsbergen. No seasonal trends could be observed from the data. Two interesting events have been examined and their source regions have been identified using atmospheric backtracking methods that deploy Lagrangian particle dispersion modelling and inversion techniques. The results are consistent with known releases of a radiopharmaceutical facility.     

Ergodicity and Earthquake Catalogs: Forecast Testing and Resulting Implications

Recently the equilibrium property of ergodicity was identified in an earthquake fault system (Tiampo et al., Phys. Rev. Lett. 91, 238501, 2003; Phys. Rev. E 75, 066107, 2007). Ergodicity in this context not only requires that the system is stationary for these networks at the applicable spatial and temporal scales, but also implies that they are in a state of metastable equilibrium, one in which the ensemble averages can be substituted for temporal averages when studying their behavior in space and time. In this work we show that this property can be used to identify those regions of parameter space which are stationary when applied to the seismicity of two naturally-occurring earthquake fault networks. We apply this measure to one particular seismicity-based forecasting tool, the Pattern Informatics index (Tiampo et al., Europhys. Lett. 60, 481–487, 2002; Rundle et al., Proc. National Acad. Sci., U.S.A., Suppl. 1, 99, 2463, 2002), in order to test the hypothesis that the identification of ergodic regions can be used to improve and optimize forecasts that rely on historic seismicity catalogs. We also apply the same measure to synthetic catalogs in order to better understand the physical process that affects this accuracy. We show that, in particular, ergodic regions defined by magnitude and time period provide more reliable forecasts of future events in both natural and synthetic catalogs, and that these improvements can be directly related to specific features or properties of the catalogs that impact the behavior of their spatial and temporal statistics.     

Polychlorinated biphenyls and hydrocarbons in bottom sediments of Pechora Basin Rivers

The quantitative concentrations of 21 congeners of polychlorinated biphenyls and 16 priority polycyclic aromatic hydrocarbons were studied in bottom sediments of the Usa River, the largest Pechora’s tributary, and its tributaries located in the central part of Timan-Pechora petroleum province. In accordance with the classification of the regional and international standards, the pollution degree of bottom sediments by organic compounds of those classes was evaluated. Pollution profiles were examined and the character of the dominating source of polychlorinated biphenyls and polycyclic aromatic hydrocarbons for bottom sediments in the region under study was identified. Key words: bottom sediments, polychlorinated biphenyls, profiles of polycyclic aromatic hydrocarbons, petrogenic, pyrogenic pollution source.     

On the synchronism in the events within the core and on the surface of the earth: the changes in the organic world and in the polarity of the geomagnetic field in the phanerozoic

The data on geomagnetic reversals are compared with the changes in the organic world and with the lower-mantle plumes. The times of the formation of plumes and the times of their appearance on the Earth’s surface relate to the intervals characterized by the different frequencies of geomagnetic reversals, i.e., there is no interrelation between the formation of plumes and the frequency of the changes in the geomagnetic field polarity. At the same time, a certain synchronism is observed between the frequency of the geomagnetic reversals and the boundaries of the biostratigraphic ages, i.e., the changes in the organic world in the long-period range. A hypothesis is proposed, which explains the change in the sign of the geomagnetic field by the combined effect of the irregular rotation of the internal core relative to the mantle and the changes in the slope angle of the axis of the Earth’s rotation, which, in turn, results in synchronous events on the Earth’s surface: the rates of changes in the organic world.     

Shear flow driven magnetized planetary wave structures in the ionosphere

The generation and further linear and nonlinear dynamics of planetary ultra-low-frequency (ULF) waves are investigated in the rotating dissipative ionosphere in the presence of inhomogeneous zonal wind (shear flow). Planetary ULF magnetized Rossby type waves appear as a result of interaction of the medium with the spatially inhomogeneous geomagnetic field. An effective linear mechanism responsible for the intensification and mutual transformation of large scale magnetized Rossby type and small scale inertial waves is found. For shear flows, the operators of the linear problem are not self-conjugate, and therefore the eigenfunctions of the problem may not be orthogonal and can hardly be studied by the canonical modal approach. Hence, it becomes necessary to use the so-called nonmodal mathematical analysis. The nonmodal analysis shows that the transformation of wave disturbances in shear flows is due to the non-orthogonality of eigenfunctions of the problem in the conditions of linear dynamics. Using numerical modeling, the peculiar features of the interaction of waves with the background flow as well as the mutual transformation of wave disturbances are illustrated in the ionosphere. It has been shown that the shear flow driven wave perturbations effectively extract an energy of the shear flow increasing the own energy and amplitude. These perturbations undergo self-organization in the form of the nonlinear solitary vortex structures due to nonlinear twisting of the perturbation’s front. Depending on the features of the velocity profiles of the shear flows the nonlinear vortex structures can be either monopole vortices or vortex streets and vortex chains.     

OSL and ESR studies of Aeolian quartz from the Upper Pleistocene loess sequence of Nussloch (Germany)

As part of a chronological study of the famous Upper Pleistocene Nussloch (Germany) loess sequence, three samples were collected to check the applicability of palaeodosimetric dating methods (OSL and ESR) to quartz grains. The ESR-multicentre method showed a partial bleaching of the ESR centers in aeolian sands. This partial bleaching was also observed by OSL. Laminated loess seemed to be sufficiently bleached but showed a large scatter of the doses, which we ascribed to heterogeneous responses of the luminescent grains to the SAR protocol. Ages could nevertheless be calculated for the three samples and were found to be somewhat older than the IRSL and ¹⁴C ages obtained for the same layers of the laminated loess.     

Long aseismic slip duration of the 2006 Java tsunami earthquake based on GPS data

The Java earthquake occurred on July 17,2006 with magnitude 7.8 associated to the subduction process of Indo-Australian plate and Sundaland block off southwestern coast of Java. We present postseismic deformation parameters of the 2006 Java earthquake analyzed using campaign GPS observation from 2006 to 2008 and continuous observation from 2007 to 2014. We use an analytical approach of logarithmic and exponential functions to model these GPS data. We find that the decay time in the order of hundreds of days after the mainshock as observed by 8 years' data after the mainshock for magnitude 7 earthquake is longer than a general megathrust earthquake event. Our findings suggest that the 2006 Java earthquake which is considered as ‘‘tsunami earthquake' most probably occurred in the region that has low rigidity and tends to continuously slip for long time periods.     

导线覆冰自动观测实验与覆冰过程分析

在贵州重冰区3个气象站和海拔2500m的梅花山野外观测点开展了3a冬季的导线覆冰自动观测实验,利用观测实验获取的大量连续覆冰过程数据,对导线覆冰重量及其气象条件逐小时演变特征进行了深入分析.结果表明:一次完整的连续导线覆冰过程包括覆冰开始、增长、维持、减弱、消融到结束五个不同的阶段,持续时间较长的覆冰过程中间可能出现间断,而覆冰增长、维持、减弱几个阶段可能重复交替出现.覆冰过程开始一般以气温下降到0℃以下且相对湿度90%以上为标志,当出现浓雾或降水时覆冰出现增长,当既无降水也无雾时覆冰进入维持阶段;整个覆冰过程中温度均低于0℃且维持很高的湿度,中途若温度上升且无雾和降水则覆冰有明显减弱,当气温稳定上升到0℃以上同时湿度下降时覆冰过程结束.覆冰过程的开始和增长一般持续时间较长,而覆冰的消融和结束则十分迅速.在气象站观测到的覆冰以雨雾混合冻结为主,降水对覆冰过程的开始和增长有重要作用,而在梅花山野外观测到的多为雾凇覆冰,降水对覆冰的作用不如地势较低地区显著.     

深部高承压水地层裂隙岩体冻结温度场实测研究

通过深部高承压水地层冻结法凿井现场实测,获得矿井裂隙岩体各个层位测温孔的温度和盐水去回路干管温度变化规律.结果表明:测温孔实测温度在冻结初期呈线性下降规律;当温度继续降低到岩石的结冰温度以后,降温速率逐步增加;当冻结帷幕达到设计温度时,实测温度变化趋于平缓;外圈管外侧测温孔降温速率最慢,两圈管之间位置的测温孔降温速率最快;位于不同位置不同层位的测温孔降温速率不一致,其中位于92m深度的卵石层(C1^#测温孔)降温速率为0.54℃·d^-1,位于209m深度的砂质泥岩(C3^#测温孔)降温速率为0.9℃·d^-1;根据实测温度可以预测地层形成冻结帷幕的交圈时间、厚度、平均温度等冻结设计参数.深部裂隙岩体冻结温度实测资料对指导冻结帷幕设计与施工具有重要实践意义.