Local and global diffusion in the Arnold web of a priori unstable systems

Using the numerical techniques developed by Froeschlé et al. (Science 289 (5487): 2108–2110, 2000) and by Lega et al. (Physica D 182: 179–187, 2003) we have studied diffusion and stochastic properties of an a priori unstable 4D symplectic map. We have found two different kinds of diffusion that coexist for values of the perturbation below the critical value for the Chirikov overlapping of resonances. A fast diffusion along some resonant lines that exist already in the unperturbed case and a slow diffusion occurring in regions of the phase space far from such resonances. The latter one, although the system does not satisfy the Nekhoroshev hypothesis, decreases faster than a power law and possibly exponentially. We compare the diffusion coefficient to the indicators of stochasticity like the Lyapunov exponent and filling factor showing their behavior for chaotic orbits in regions of the Arnold web where the secondary resonances appear, or where they overlap.     

Origin of V. Grib pipe eclogites (Arkhangelsk region,NW Russia): geochemistry,Sm-Nd and Rb-Sr isotopes and relation to regional Precambrian tectonics

Mineralogy and Petrology - In this paper, new main and trace elements and isotopic data are presented for 14 coarse-grained eclogite xenoliths from the V. Grib kimberlite pipe in the central part...     

Relation between basin morphometric features and dynamic characteristics of debris flows——a case study in Siberia,Russia

Extreme and prolonged rainfall in the Tunka Ridge caused several debris flows in the vicinity of the Arshan village(Siberia, Russia) on June 28, 2014. These debris flows, in spite of similar geological conditions, had different velocity, peak discharge and alluvial fan volume values. The flow velocity was from 3.5 m/s to 19.6 m/s, the peak discharge ranged from 63 m3/s to 13566 m3/s, and the alluvial fan volume varied from 4.13×103 to 8.45×105 m3. Such a great range of values is due to the morphometric parameters of the debris flow basins. The article deals with the influence of morphometric parameters of debris flow basins, such as the basin area, the average slope, Melton ratio, relief ratio on the debris flow velocity, peak discharge and volume of alluvial fans. In this debris flow event the average values of slope angle and total basin relief of the debris flow basins did not affect the values of debris flow velocity, peak discharge and alluvial fan volume. The highest correlations were observed with the debris flow basin area that was connected with the water inflow volume into the debris flow basins during the rainfall. The unequal water distribution among debris flow basins also had an impact on the debris flow velocity, peak discharge and volume of alluvial fans.     

Effects of long-term medieval agriculture on soil properties: A case study from the Kislovodsk basin,Northern Caucasus,Russia

The chemical properties and biological activities of soils were studied in the vicinity of the medieval settlement Podkumskoe-3 in the Kislovodsk basin (Northern Caucasus, Russia). Between the 5th and 8th centuries this area was ploughed regularly, but it was then abandoned up to the present day. It has been established that past human activity leads to soil undergoing significant transformations in terms of microbial communities and enzyme activity, and that such changes are maintained over long periods. Long-term manuring in the middle of the first millennium AD led to an increase in organic carbon content and the accumulation of nitrate nitrogen. Soils of ancient abandoned fields are associated with increases in microbial biomass, number of saprotrophic bacteria, urease activity, and fungal mycelium biomass. The observed changes in the microbiological and biochemical properties of soil were conditioned by secondary anthropogenically induced succession after the abandonment of arable lands.     

Lakes of the Jom-Bolok Volcanoes Valley in the East Sayan Mts., Baikal region

Journal of Geographical Sciences - This article describes the lake basins of the Jom-Bolok volcanic region in the East Sayan (the largest manifestation of the Holocene eruptions in Central Asia)....     

A Statistical Upscaling Workflow for Warm Solvent Injection Processes for Heterogeneous Heavy Oil Reservoirs

Natural Resources Research - Hybrid solvent- and thermal-based methods offer an important potential for reducing the environmental impact and enhancing recoveries in heavy oil production processes....     

Graph theory for analyzing pair-wise data: application to geophysical model parameters estimated from interferometric synthetic aperture radar data at Okmok volcano,Alaska

Graph theory is useful for analyzing time-dependent model parameters estimated from interferometric synthetic aperture radar (InSAR) data in the temporal domain. Plotting acquisition dates (epochs) as vertices and pair-wise interferometric combinations as edges defines an incidence graph. The edge-vertex incidence matrix and the normalized edge Laplacian matrix are factors in the covariance matrix for the pair-wise data. Using empirical measures of residual scatter in the pair-wise observations, we estimate the relative variance at each epoch by inverting the covariance of the pair-wise data. We evaluate the rank deficiency of the corresponding least-squares problem via the edge-vertex incidence matrix. We implement our method in a MATLAB software package called GraphTreeTA available on GitHub (https://github.com/feigl/gipht). We apply temporal adjustment to the data set described in Lu et al. (Geophys Res Solid Earth 110, 2005) at Okmok volcano, Alaska, which erupted most recently in 1997 and 2008. The data set contains 44 differential volumetric changes and uncertainties estimated from interferograms between 1997 and 2004. Estimates show that approximately half of the magma volume lost during the 1997 eruption was recovered by the summer of 2003. Between June 2002 and September 2003, the estimated rate of volumetric increase is \((6.2 \, \pm \, 0.6) \times 10^6~\mathrm{m}^3/\mathrm{year} \). Our preferred model provides a reasonable fit that is compatible with viscoelastic relaxation in the five years following the 1997 eruption. Although we demonstrate the approach using volumetric rates of change, our formulation in terms of incidence graphs applies to any quantity derived from pair-wise differences, such as range change, range gradient, or atmospheric delay.     

Environmental and political implications of Vietnam's water vulnerabilities: A multiscale assessment

Vietnam's low‐lying areas of the Lower Mekong Basin are prone to floods, salt water inundation, and riparian competition with upstream neighbours. Vietnam's opening to the global economy, accompanied by industrialization and a rapidly growing population, impose multiscale (global, regional, local) stresses on urban and rural water systems resulting in water contamination and groundwater overdraft. Water vulnerability is a function of both natural and social hazards and depends on the scope of capital investment, political and ideological institutions, managerial capacity and governance. Water distribution and riparian ecosystem health are also hydropolitical issues related to dam‐building activity by Vietnam and its transboundary neighbours, Laos, Cambodia and particularly China, whose territory contains the source of the Mekong River. A multiscale assessment of Vietnam's interlinked water vulnerabilities indicates that the resilience of the country's social‐ecological water system rests on peaceful resolution of regional transboundary conflicts based on shared economic interests and on improved managerial practices of local authorities.