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

V. B. Zaalishvili  D. A. Mel’kov 《Izvestiya Physics of the Solid Earth》2014,50(5):707-718

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.  相似文献   

Instrumental geophysical monitoring in the territory of northern Caucasus     

V. B. Zaalishvili  N. I. Nevskaya  D. A. Mel’kov 《Izvestiya Physics of the Solid Earth》2014,50(2):263-272

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.  相似文献   

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

Vol’vach  L. N.  Vol’vach  A.E.  Larionov  M.G.  MacLeod  G. C.  van den Heever  S. P.  Wolak  P.  Olech  M.  Ipatov  A.V.  Ivanov  D.V.  Mikhailov  A. G.  Mel’nikov  A.E.  Menten  K.  Belloche  A.  Weiss  A.  Mazumdar  P.  Schuller  F. 《Astronomy Reports》2019,63(1):49-65

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...  相似文献   

The thermochemical study of natural lithium micas-zinnwaldite and protolithionite     

L. P. Ogorodova  L. V. Mel’chakova  I. A. Kiseleva  T. N. Shuriga 《Geochemistry International》2009,47(5):526-529

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

V. A. Stepanov  A. V. Mel’nikov 《Geology of Ore Deposits》2017,59(2):131-140

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.  相似文献   

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

Beatriz González-Fernández  Mónica Meléndez-Asensio  Eduardo Menéndez-Casares 《Environmental Earth Sciences》2009,59(4):913-928

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.  相似文献   

Statistical analysis of high-frequency decimetric type III bursts     

Meléndez  J.L.  Sawant  H.S.  Fernandes  F.C.R.  Benz  A.O. 《Solar physics》1999,187(1):77-88

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.  相似文献   

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

Michael Hickman  Mel A. Reasoner 《Journal of Paleolimnology》1998,20(3):253-265

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.  相似文献   

Study of the optical variability of T Tau in the period 1962–2003     

S. Yu. Mel’nikov  K. N. Grankin 《Astronomy Letters》2005,31(2):109-116

We present the results of our long-term U BV R observations of the star T Tauri performed at Mt. Maidanak Observatory from 1986 until 2003. These data, together with previous photoelectric observations of other authors, suggest that the long-term variations of the light curve are not periodic, but have a cycle with a time scale of 6–9 yr. The light curve also exhibits slower variations with time scales of ～30–40 yr. We confirm the existence of periodic brightness variations with a period of \(P = 2\mathop .\limits^d 798\) over many years; this process is peculiar in that the phase and shape of the phase curve change from season to season. We analyze the color behavior of the star. We found evidence of a strong flare occurred on October 5, 1999, when the brightness of the star reached \(9\mathop .\limits^m 22\). This is the strongest flare recorded during its photoelectric observations.  相似文献   

Spatialization of the SNOWPACK snow model for the Canadian Arctic to assess Peary caribou winter grazing conditions     

F. Ouellet  A. Langlois  E. A. Blukacz-Richards  C. A. Johnson  A. Royer  E. Neave 《自然地理学》2017,38(2):143-158

Abstract

Peary caribou is the northernmost designatable unit for caribou species, and its population has declined by about 70% over the last three generations. The Committee on the Status of Endangered Wildlife in Canada identified difficult grazing conditions through the snow cover as being the most significant factor contributing to this decline. This study focuses on a spatially explicit assessment tool using snow model simulations (Swiss SNOWPACK model driven in an off-line mode by spatialized meteorological forcing data generated by the Canadian Regional Climate Model) to characterize snow conditions for Peary caribou grazing in the Canadian Arctic. The life cycle of Peary caribou has been subdivided into three critical periods: summer foraging and fall breeding (July–October), winter foraging (November–March), and spring calving (April–June). Winter snow conditions are analyzed and snow simulations compared to Peary caribou island counts to identify a snow parameter that could potentially act as a proxy for grazing conditions and explain fluctuations in Peary caribou numbers. This analysis concludes that caribou counts are affected by simulated snow density values >300 kg m^?3. A software tool mapping possibly favorable and unfavorable grazing conditions based on snow is proposed at a regional scale across the Canadian Arctic Archipelago. Specific output examples are given to show the utility of the tool, mapping pixels with cumulative snow thickness above densities of 300 kg m^?3, where cumulative seasonal thicknesses >7000 cm are considered unfavorable.  相似文献