Identifying induced variations in the seismic regime by the methods of nonlinear dynamics

The nonlinear analysis of the data on seismicity in the areas where the underground rocks were affected by the injection of fluids, blasting works, and vibrations shows that the technogenous impacts increase the regularity of the seismic regime. The effects of the man-made actions manifest themselves in the formation of stable states characterized by the finite fractal dimension of the attractor and the small dimension of the embedding space. In order to explain the increase in the regularity of the seismic process, we consider the model of motion in the fault zones which is described by the two-parameter friction law. The presence of the stable states paves the way for both forecasting the induced seismic activity and developing the technologies for the controlled forcing of the seismic regime.     

Intensity and polarization of the hard X-ray radiation of solar flares at the top and footpoints of a magnetic loop

The spatial distributions of the intensity and polarization of hard X-rays (HXR) were modeled based on a numerical solution of the nonstationary kinetic Fokker-Plank equation. Two cases of nonstationary long injections (??10 s) of nonthermal electrons at the top of a flaring loop are considered. In the first case, the injection occurs anisotropically in a cone directed along the field to one of the loop??s footpoints. In the second case, electrons are injected isotropically. In the case of the anisotropic injection, the degree of HXR polarization in the footpoints is low and does not exceed 8%. At the same time, the polarization of the radiation from the top in a range of photon energies from 30 to 60 keV reaches 43% at the beginning of injection. Significantly different spatial distributions of HXR characteristics are obtained for the isotropic injection of electrons. In this case, the calculated degree of HXR polarization from the top exhibits a strong variability: it reaches 15?C18% at the beginning of injection at photon energies of 30?C90 keV, decreases to zero after 5 s, and then, changing its sign, increases to 8%. In the footpoint of the loop, HXR is in fact nonpolarized. The features of the spatial distributions obtained in the simulation process can be measured with X-ray telescopes-polarimeters in future experiments and used for diagnosing the pitch angle distribution of accelerated electrons.     

Reconstructing the Kolka surge on September 20, 2002 from the instrumental seismic data

The process of the Kolka rock and ice avalanche on September 20, 2002 in the Karmadon Gorge, North Ossetia is reconstructed based on analyzing the instrumental seismic records. The results of calculating the velocities of the rock-ice mass movement on the interval from the Maili Glacier to the Karmadon Gate agree with the results of mathematical modeling the avalanche flow in a gorge. The macroseismic effect of the surge impact on the rocks in the region of the Karmadon Gate is investigated from seismic data and the results of surveying the territory carried out by the authors in 2003–2004.     

Instrumental geophysical monitoring in the territory of northern Caucasus

Because of the activation of natural hazardous processes in the Caucasus, including the sudden Kolka-Karmadon rock-ice slide on September 20, 2002, the integrated observation system (Karmadon parametric test area) was organized at the end of 2003. The purpose of its operation is the instrumental investigation of hazardous natural and anthropogenic geological processes in the mountain areas.     

A Giant Water Maser Flare in the Galactic Source IRAS 18316-0602

Astronomy Reports - The results of long-term monitoring of the Galactic maser source IRAS 18316–0602 (G25.65+1.05) in the water-vapor line at frequency f = 22.235 GHz (616–523...     

Tokur gold ore–placer cluster in Amur Province: Geological–structural features and perspective of its development

The geological–structural features and gold-potential perspective of the Tokur ore–placer cluster in the Amur Province have been studied. This ore–placer cluster is a syncline composed of Paleozoic blackshale sequence, which is cut through by Late Paleozoic and Late Mesozoic intrusions. A granitoid massif is suggested at the depth on the basis of geophysical data. The cluster is distinguished by high productivity. Approximately 37 t gold from ore deposits, primarily from the Tokur deposit, and 60 t from placers have been mined out. The Tokur deposit is compared with the Natalka and Degdekan deposits from the Yana–Kolyma Province. Perspectives of the cluster area for large gold–quartz deposits and technogenic gold placers have been estimated.     

Hydrogeological characterization of carbonated Jurassic aquifers in the Gijón-Villaviciosa basin (Asturias,N Spain) by means of geochemical and isotopic techniques

Chemical and isotopic analyses of groundwater from the carbonated Jurassic aquifers in the Gijón-Villaviciosa basin (Asturias, northern Spain) were carried out. Nine springs were sampled to determine major cations and anions, as well as the stable isotopes of the water molecule (δ²H and δ¹⁸O) and sulphate (δ³⁴S) values. Also, δ³⁴S values from gypsum coming both from Triassic rocks and bottom of Jurassic sequence were also determined. The results obtained were used to classify the waters with a genetic criteria in three groups: (1) waters with a high gypsum influence, with sulphate coming from Jurassic gypsum, (2) waters without gypsum influence, where sulphate source could be atmospheric deposition from industrial processes and marine aerosol, and (3) waters with some gypsum influence, in which sulphate origin could be a combination of different sources. In relation to recharge, δ²H and δ¹⁸O values were close to those of Global Meteoric Water Line and fit a local line that suggests a meteoric origin. The estimated elevations for spring recharge are in agreement with those obtained from hydrogeological maps.     

Statistical analysis of high-frequency decimetric type III bursts

Here we report the statistical analysis of 160 isolated decimetric type III bursts, a majority of them (74%) having central frequency above 1000 MHz, observed in 8 flares by the spectrometer Phoenix. The most important finding of the detailed analysis is: 67% of all the bursts are reverse slope, 38% normal and 5% bi-directional. Also, we obtained the following results: (a) the best fits for the average half power duration and for the average drift rate as a function of frequency are given by t_1/2=1.7×10⁴f^–0.60and /df/dt|=(0.09±0.03)f^{(1.35 ± 0.10)}, respectively; (b) the frequency range of most of the type III bursts is less than 250 MHz; (c) the number of bursts decreases with increasing starting frequency and flux; (d) peak flux decreases with increasing frequency. The relations obtained fit well for higher frequency observations. Assuming an improved density model and type III emission at 2^ndharmonic, the beam parameters of type III bursts are determined.     

Late Quaternary diatom response to vegetation and climate change in a subalpine lake in Banff National Park, Alberta

The late Quaternary diatom record from subalpine Crowfoot Lake, Banff National Park, Alberta (lat. 51° 61N; long. 116° 31W) has been analyzed. Results are related to independently inferred vegetation and climate changes. No diatoms were found in the basal diamict that predates 11330 ¹⁴C yr BP. Very few occur until ca. 10 100¹⁴ C yr BP probably due to the short time between de-glaciation and an advance of the Crowfoot Glacier during the Younger Dryas Chron. Initial pioneering species were characteristic of alkaline water and calcareous organic sediments. They appeared as sediments became organic and laminated suggesting increasing water clarity, and as the Pinus-dominated forest expanded and the climate warmed. After ca. 9060 ¹⁴C yr BP diatom numbers increased rapidly, reaching a maximum prior to the Mazama tephra; they remained high until ca. 3500 ¹⁴C yr BP. The period between ca. 9060 and 3500 ¹⁴C yr saw timberline elevation increase and the dominance of xerophytic taxa. These are consistent with early to mid-Holocene warmth and aridity. Diatom productivity reflects the warm climate and presumably longer ice-free season, a stable catchment and transparent water. Decreases in diatom productivity coincide with a vegetation change with reduction of xerophytic taxa and the appearance of a closed Picea-Abies forest, hence a cooler, wetter climate at ca. 4100 to 3500 ¹⁴C yr BP. The diatom numbers during the Neoglacial were of the same magnitude as prior to ca. 9060 ¹⁴C yr BP. Small species of Fragilaria (overwhelmingly Fragilaria construens v. venter) became extremely dominant during the period of high diatom productivity, and remained so thereafter. Recovery of the lake appears to have been rapid after deposition of the Mazama tephra. Maximum occurrence of Cyclotella radiosa occurred ca. 8000 ¹⁴C yr BP during the warm early Holocene and may reflect this warmer climate, a longer ice-free season than presently, perhaps less turbid water, or it may reflect a subtly higher nutrient status of the lake water. The diatom record of Crowfoot Lake has responded with sensitivity, particularly in terms of productivity, to the Holocene vegetation and climate changes.