FOREWORD

Foreword

FOREWORD     

Russian cross-border shopping tourists in the Finnish and Polish borderlands

Cross-border shopping and tourism are worldwide phenomena, appearing at any border with at least some degree of permeability. The authors investigate the range of cross-border shopping and tourism activities practised by Russians at two of the EU’s external borders, one between Finland and the Leningrad Oblast, and the other between Poland and the Russian exclave of Kaliningrad Oblast. The study is based on research conducted in the Polish–Russian and Finnish–Russian border regions between 2013 and 2015, when the authors held interviews, administered survey questionnaires, and engaged in participant observation. The information was supplemented with data from the Finnish and Polish Border Guard services. Based on the results of the fieldwork, the authors argue that cross-border shopping and tourism are often combined during the same trip, and thus constitute a specific form of cross-border activity. Their study sheds light on how cross-border shopping tourism depends on and is interconnected with more than just the factor of the non-availability of goods and services. They conclude that cross-border shopping at the Polish–Russian border and the Finnish–Russian border has become more like a Western European practice, namely shopping for pleasure.     

Continuous gas monitoring in the West Bohemian earthquake area,Czech Republic: First results

Two stations monitoring concentrations of carbon dioxide and radon in soil gas (Oldřišská and Novy Kostel) and one station monitoring flow of carbon dioxide at a mofette (Soos) have been operated in the area of the West Bohemian earthquake swarms. We present preliminary results obtained on the base of four-year observations. We found that data are not influenced considerably by barometric pressure. Although the CO₂ concentration varies greatly, the long-term trends at stations Oldřišská and Novy Kostel are similar, which indicates that the CO₂ flow is controlled by common geogenic processes. Also temporal trends of CO₂ and Rn concentrations in soil gas at individual stations are analogous. We found diurnal variations of both CO₂ concentration in soil gas and the CO₂ flow at mofettes due to the earth tides. A response to tides of semi-diurnal period is insignificant in CO₂ concentration and only weak in the CO₂ flow. We also examined possible pre-seismic, co-seismic and post-seismic effects of the intensive 2008 earthquake swarm on the CO₂ concentration at Oldřišská and Novy Kostel, and on the CO₂ flow at Soos. However, all potential indications were insignificant and there has not been proven any influence of the swarm on the CO₂ concentration as well as on the CO₂ flow. Nevertheless, a gradual decrease of amplitudes of diurnal variations before the swarm and the lowest amplitudes during the swarm is a noteworthy phenomenon, which might indicate the strain changes of the rock associated with earthquake swarm.     

Modelling the wave phenomena in acoustic and elastic media with sharp variations of physical properties using the grid‐characteristic method

This paper introduces a novel method of modelling acoustic and elastic wave propagation in inhomogeneous media with sharp variations of physical properties based on the recently developed grid‐characteristic method which considers different types of waves generated in inhomogeneous linear‐elastic media (e.g., longitudinal, transverse, Stoneley, Rayleigh, scattered PP‐, SS‐waves, and converted PS‐ and SP‐waves). In the framework of this method, the problem of solving acoustic or elastic wave equations is reduced to the interpolation of the solutions, determined at earlier time, thus avoiding a direct solution of the large systems of linear equations required by the FD or FE methods. We apply the grid‐characteristic method to compare wave phenomena computed using the acoustic and elastic wave equations in geological medium containing a hydrocarbon reservoir or a fracture zone. The results of this study demonstrate that the developed algorithm can be used as an effective technique for modelling wave phenomena in the models containing hydrocarbon reservoir and/or the fracture zones, which are important targets of seismic exploration.     

Historical floods within the Selenga river basin: chronology and extreme events

Large floods are among the most hazardous natural phenomena, which in many cases cause enormous losses to the economy and lead to human casualties. Along with the use of modern instrumental data, the analysis of historical information on large past floods is widely practiced in the world. This allows obtaining qualitative and quantitative characteristics of historical floods and significantly expanding the observation series. The Selenga River is one of the largest rivers of Central Asia with catchment area equal to 447,060 km², and also it is rather flood-prone river. The hydrological regime of the Selenga River is quite well studied in the twentieth century on the basis of gauging stations data, but there is still a lack of knowledge about past floods. In this paper, we present a list of 26 known floods within the Selenga River basin from 1730 to 1900, compiled from available historical documents (newspapers, scientific reports, diaries, memoirs, etc.). We estimated peak water levels for three catastrophic floods (1830, 1869 and 1897), the historical maximum of which was 850 cm. The reliability of our estimates is confirmed by a comparative analysis of the large 1971 flood. It was revealed that the largest floods can cause a rise of the Lake Baikal water level up to 200 cm. The inflow to Lake Baikal resulting from the largest floods in the Selenga River basin is comparable to the average annual inflow of water into the lake. We can conclude that the use of historical data for the analysis of floods in Eastern Siberia is quite acceptable, but some limitations must be taken into account.

     

New data on earthquake focal mechanisms in the Laptev Sea region of the Arctic-Asian seismic belt

We consider 16 earthquakes with M_w?=?4.2–5.2 that occurred in the south-eastern part of the Laptev Sea shelf, Lena River Delta, and North Verkhoyanye (Russia) in 1990–2014. Focal mechanisms, scalar seismic moments, moment magnitudes, and hypocentral depths of the seismic events have been calculated from the data on amplitude spectra of surface waves and P wave first-motion polarities. The obtained results sufficiently implement the existing dataset on reliable earthquake source parameters for the study region and prove the change of the stress-strain state of the crust from extension on the Laptev Sea shelf to compression on the continent providing finer spatial details of the deformation field in the transition zones such as Buor-Khaya Bay and the Lena River Delta.     

Uranyl adsorption at (0 1 0) edge surfaces of kaolinite: A density functional study

We report density functional investigations of kaolinite edge surfaces and uranyl adsorption thereon. Applying periodic slab models, we studied the (0 1 0) surface of kaolinite as an example of kaolinite edge facets which are expected to be highly reactive and to adsorb preferentially metal ions. Among the four terminations of the (0 1 0) surface, we selected the two most likely ones and determined their structures to be affected by solvation. On these modified surfaces, we explored bidentate inner-sphere adsorption complexes of uranyl, at single metal center sites, Al(O,OH), and sites of mixed type, AlOH-SiO. On one of the terminations hydrolysis of uranyl was found to occur. Comparison of key calculated structure parameters with available experimental data suggests an extension of the prevailing interpretation and implies that a set of uranyl complexes may coexist on edge surfaces.     

The thermo-tectonic history of the Song-Kul plateau, Kyrgyz Tien Shan: Constraints by apatite and titanite thermochronometry and zircon U/Pb dating

The Song-Kul Basin sits on a plateau at the Northern and Middle Kyrgyz Tien Shan junction. It is a lacustrine basin, occupied by Lake Song-Kul and predominantly developed on igneous basement. This basement was targeted for a multi-method chronological study to identify the different magmatic episodes responsible for basement formation and to constrain the timing of the development of its present-day morphology. Zircon U/Pb dating by LA-ICP-MS revealed four different magmatic episodes: a Late Cambrian (~ 500 Ma) island arc system, a Late Ordovician (~ 450 Ma) subduction related intrusion, an Early Permian (~ 290 Ma) collisional stage, and a Middle to Late Permian (~ 260 Ma) post-collisional magmatic pulse. Middle to Late Triassic (~ 200–230 Ma) titanite fission-track ages and Late Triassic – Early Jurassic (~ 180–210 Ma) apatite fission-track ages and thermal history modeling indicate the Song-Kul basement was already emplaced in the shallow crust at that time. An exhumed fossil apatite fission-track partial annealing zone is recognized in the bordering Song-Kul mountain ranges. The area experienced only minor post-Early Mesozoic denudation. The igneous basement was slowly brought to apatite (U–Th)/He retention temperatures in the Late Cretaceous–Palaeogene. Miocene to present reactivation of the Tien Shan does not manifestly affect this part of the orogen.