South Kuril Research Articles

Flexural bending curvature and yield zone of subducting plates

ABSTRACT We quantify flexural deformation of subducting oceanic plates at a global array of 15 ocean trenches, using a new approach of modelling spatial variations in flexural bending shape and curvature. The investigated trenches are chosen to represent a diverse range of subducting plate age of 24–150 Ma, including the Middle America, Peru, Chile, West and East Aleutian, Sumatra, North and South Philippine, Tonga, Kermadec, Kuril, Japan, Izu-Bonin, and South and North Mariana. The studied trenches show systematic intra- and inter-trench variability in the calculated flexural bending curvature, stress distribution, extensional brittle yield zone, and effective elastic plate thickness Te of the subducting plates. We find that subducting plate age is a critical factor controlling the bending curvature and the corresponding extensional yield zone. The width, depth, and area of the extensional yield zone are all calculated to increase systematically with the subducting plate age. The newly-developed curvature analysis can yield continuously varying apparent Te(x) from the trench axis to outer rise. The calculated extensional yield zones from the curvature analysis are in general consistent with the observed normal faulting earthquakes of magnitude≥6.0 at the 15 global trenches. Our analyses also reveal that the five deepest regions of the global trenches, i.e. the Challenger, Horizon, Serena, and Scholl Deeps and Galathea Depth, are associated with relatively large flexural bending and calculated yield zones comparing to their respective adjacent trench segments. The Serena and Challenger Deeps of the S. Mariana trench are calculated to have the largest flexural bending among the five deeps.

The bryophyte flora of northern Iturup (north-west Pacific): between the circumboreal and East Asian floristic regions

ABSTRACTIntroduction. The Kuril Islands Chain demarcates the boundary between the circumpolar and East Asian floras in the amphi-Pacific and is a trans-Oceanic migration route from warm-temperate insular East Asia to north-east Asia and Beringia. This paper reviews the flora of the northern part of Iturup Island in regards to its bryogeography and taxonomic diversity, as well as its relative position among other bryophyte floras of north-east and East Asia.Methods. The paper uses morphological methods to identify the species composition and detrended correspondence analysis to identify the position of the northern Iturup Island in the system of local floras of the eastern, extra-tropical, Pacific.Key results. The flora is closely related to the bryophyte floras of the southern Kurils and Hokkaido Island, but has been found to be distinctly distant from the ‘true’ cool-temperate East Asian floras, as well as from the boreal and hemiarctic floras of north-east Asia. Instead, the floras of the south Kurils and northern Hokkaido Island belong to a peculiar intermediate phytogeographic province that cannot be unambiguously placed in either the East Asian or circumboreal floristic regions. The hemiboreal character of the bryophyte flora of northern Iturup Island is in contrast to the general appearance of many of the dominant vegetation communities on the island, which are more characteristic of the hemiarctic.Conclusion. There is no robust evidence to refer the bryophyte flora of northern Iturup either to the circumboreal or East Asian Floristic Region, the flora belongs to a unique intermediate province between the two regions.

The Population Genetic Organization of Pacific Cod Gadus macrocephalus in the North Pacific Based on Microsatellite Analysis

Six groups have been identified in the species' population structure based on the analysis of microsatellite markers' polymorphism in Pacific cod Gadus macrocephalus samples within the entire western part of the North Pacific, including waters of the Pacific coast of Canada. The first group includes cod from waters of the Yellow Sea; the second group consists of cod from the Sea of Japan (eastern coast of Korea and Peter the Great Bay); the third group combines cod from Tatar Strait and the South Kuril Islands (both Sea of Okhotsk and Pacific Ocean sides); the fourth group is formed by cod from the northwestern Sea of Okhotsk and Taui Bay; the fifth-largest group includes cod from waters off western Kamchatka, the North Kuril Islands (Sea of Okhotsk and Pacific Ocean sides), Karaginsky Bay, Navarinsky area in the Bering Sea, and Anadyr Bay; the sixth group is formed by cod from coastal waters of Canada.

The first record of catastrophic windthrow in boreal forests of South Sakhalin and the South Kurils (Russia) during October 2015 tropical cyclones

The first record of catastrophic windthrow in boreal forests of South Sakhalin and the South Kurils (Russia) during October 2015 tropical cyclones

Прогнозирование численности кеты на Южных Курильских островах

Прогнозирование численности кеты на Южных Курильских островах

ИССЛЕДОВАНИЕ ИНФОРМАТИВНОСТИ ОБЪЕМНОЙ АКТИВНОСТИ ПОЧВЕННОГО РАДОНА ПРИ ПОДГОТОВКЕ И РЕАЛИЗАЦИИ ТЕКТОНИЧЕСКИХ ЗЕМЛЕТРЯСЕНИЙ НА ПРИМЕРЕ ЮЖНО-КУРИЛЬСКОГО РЕГИОНА

The authors analyzed monitoring data of VRA (volume radon activity) from the stations Yuzhno-Kurilsk and Kurilsk collected since 2011. The data allowed us to analyze the dependence of seismic events in the variations of the VRA. In the analysis we used only events that answer the relationship between earthquake magnitude and the logarithm of the distances greater than 2.5. In order to characterize the position of the moment of the seismic event on the VRA curve, the duration of the anomaly, the time from the beginning of the anomaly to the tectonic event, the time from the extremum to the event, and the time from the end of the anomaly to the event were determined. The analysis showed that the distinctive variations in the volume activity of soil radon for the setting of the South Kuril region begin a few days prior to the event that causes them, i.e. relate to the short-term precursor effects; tectonic events on the curve of the change of the VRA are not observed on the ascending branch of the anomaly; tectonic events with different distances from a recording station are observed on different parts of the VRA curve; the radius of the near field is 50-70 kilometres.

Штормовое волнение на Южных Курильских островах по данным визуальных и инструментальных измерений

Штормовое волнение на Южных Курильских островах по данным визуальных и инструментальных измерений

New map of tsunami-hazard for the south Kuril Islands

The tsunami-zoning map (possible tsunami heights of a frequency of 1 event within 50 and 100 years) for the coast of the South Kuril Islands have been updated (former map have been developed in 2006). The update is based on the development of the tsunami-activity model, mainly due to the increase of the number of basic coastal locations (from 18 to 62) for which the parameters of the recurrence function were estimated, as well as on the modernization of the numerical model. Serious progress in simulations was achieved in setting the initial conditions, using the seismic tsunami source model. Field surveys on the coast to search for traces of historical and paleotsunami, as well as qualitative documentation of the Tohoku tsunami manifestations allowed to clarify the model of tsunami-activity in Southern Kuril Islands. The sufficiently large amount of data in this case (which is generally untypical for the tsunami) allowed authors, to apply the statistical approach for evaluation of the tsunami hazard distribution along the coast. Estimates of tsunami heights were spread from the basic coastal locations to adjacent parts of the coast using detailed simulation of all significant tsunamis and calculating wave heights at the shoreline. The detailed maps of tsunami-hazard at scale 1:100,000 have been made for the settlements of Yuzhno-Kurilsk, Kurilsk, Malokurilskoe, and Krabozavodskoe.

Local Evolutionary Processes in the Forest Ecosystems of Volcanic Islands of the Northwestern Pacific

Data of large-scale landscape-ecological survey performed on the test ground in the vicinity of the Mendeleev Volcano (Kunashir Island, South Kurile Ridge) were used for empirical-statistical modeling of forest ecosystems characterizing one of the initial stages of geological history of the continental biosphere formation in the Pacific Mobile Belt. The causal mechanisms for the lowering of the boundaries of altitudinal bioclimatic belts and the southward shift of natural zones on extratropical Neo-Pacific islands compared to the neighboring continent were revealed. The evolutionary significance of the insular-arc bioclimatic system is characterized. Two phenomena of structural-functional organization of the Mendeleev volcanic landscape have been revealed. First, there is an exceptionally high system-forming role of forest phytobiota in the formation and development of young volcanic landscapes. The forest communities of the insular Neo-Pacific in the south of the boreal belt are characterized by an annual turnover of plant matter falling into the category of intensive metabolism and being typical only of subtropical forests by the zonal standards. Second, the intense annual turnover of the above-ground phytobiota and the high rate of the entire biological cycle in the southern Kunashir landscapes are the main factors of their stability under the conditions of “cold” oceanicity and, together with magmatic geotherms, contribute to the formation of subboreal “climatically unjustified” forests. The energy bases of productivity of forest communities of the island-arc Neo-Pacific have been analyzed as a focus of local and regional diversity of terrestrial ecosystems, which develops further on the continent. The mechanisms of formation (at the topological level) of new intrazonal types of ecological systems, which serve as the driving force of evolutionary processes, have been revealed. It is shown that evolutionary tendencies in plant cover emerge already at the initial, volcanogenic stage of formation of the continental biosphere.

Storm surges and extreme storms in Sakhalin Island and South Kuril Islands

Storm surges (the significant sea level rises due to a drop in surface atmospheric pressure and an increase in wind velocity during the passage of deep cyclones over the coastal areas) pose a formidable threat to the coastal settlements of Sakhalin and the South Kuril Islands. As a result of flooding of coastal areas, the impact of storm waves on the shores and coastal facilities is sharply increased. The greatest damage caused by surges on 10.11.1990 and 9.11.1995 which affected the most populated southern part of Sakhalin Island. A long-term sea level series were analyzed, recorded at 9 coastal tide gauges located on the coast of Sakhalin Island and South Kuril Islands. Estimates for the maximum heights of the storm surges and tidal level were obtained separately, as well as for the rare recurrence of the total sea level height with the probability of these individual components superposition. The maximum total height of the sea level was obtained for the Kurilsk station, where the highest storm surge was recorded. The minimum values were obtained for southwestern coast of Sakhalin Island (Kholmsk and Nevelsk stations) were tides are small. Seasonal and inter-annual variations of strong waves were analysed from the data of visual observations.

Geology, magmatism, metallogeny, and geodynamics of the South Kuril islands

Intense fluid thermal fluxes in the continental lithosphere and crust from sub- and supra-subduction asthenospheric zones were the root cause of the formation of magmatic chambers and the development of volcanism and multimetal ores. We demonstrate this phenomenon using the example of the South Kuril.The southern chain (including the large Kunashir, Iturup, and Urup islands) of the Greater Kuril Ridge of the “island arc-trench” system is confined to the northwestern Pacific subduction megazone. Inherited transform faults (Nosappu, Iturup, and Urup) occur in the oceanward part of the SSE segment of the Kuril-Kamchatka trench. Repeated movements of the oceanic region sandwiched between the fault zones were accompanied by earthquakes and low-volume petit-spot-type submarine eruptions of highly alkaline basaltic rocks. The latter were sourced from an asthenospheric mantle beneath the oceanic slab. Recurrent manifestations of compressional to extensional stresses in the subduction zone during the Oligocene-Neogene and Pleistocene-Holocene were accompanied by under and overthrusting and earthquakes.

Landscape response to the Medieval Warm Period in the South Russian Far East

The landscape changes during the Medieval Warm Period were discussed for the Kuril and Sakhalin Islands, Primorye and the Amur River Basin. Some paleoclimatic parameters and shifts in landscape boundaries were estimated. The environmental changes on the Kuril Islands were manifested mostly in changes of areas occupied by the same plant communities that we see now in modern landscapes. The paleoenvironmental changes in the North and Central Kurils have been partly hidden due to volcanic ashfalls. On Simushir Island birch forests expanded at the expense of diminished tundra landscapes. On the South Kurils, the warming led to the increasing importance of broadleaf trees. In dark coniferous forests, the fir proportion increased. On small islands devoid of forests, the changes in the shrub and herb composition indicated warmer and less humid conditions. On Sakhalin, there were certain distinctions in the changes in the paleolandscape between the north, which was devoid of thermophilic elements in the forests and the south, which belonged to the zone of dark coniferous forests with an admixture of broadleaf trees. In Primorye, the warming caused an increase in the proportion of Korean pine and broadleaf species in the forests, as well as fir prevalence in dark coniferous forests. In the Amur River region, the warming involved considerable changes in the forests, which were expressed by an increase in the role of thermophilic species in the reduction of the proportion of dark coniferous species. The spread of broadleaf trees on the continental and island coasts could be influenced by warm currents amplifying the warming effect. In all regions, the warming was accompanied by a minor transgression. The sea level was higher than at present by ∼1 m, which resulted in the formation of low marine and lagoon terraces, the attenuation of eolian processes on the coasts, and the fixation of coastal dunes with the development of a thick soil.

Population Structure of Pacific Cod Gadus macrocephalus in the Southern Part of the Range Based on the Microsatellite Analyses

The population structure of Pacific cod Gadus macrocephalus in the southern part of the range and adjacent regions is studied on the basis of the results of microsatellite analyses. Collected data indicate heterogeneity of this species population within the studied area. According to the obtained FST values, Pacific cod from the waters of the Republic of Korea (Yellow Sea side) and northwestern part of the Sea of Okhotsk significantly differ from all other studied regions (Table 4). Significant differentiation was also revealed between samples from the waters of the Tatar Strait and all other regions except for South Kurils Pacific cod (both Sea of Okhotsk and Pacific Ocean sides). These two latter sample collections were similar to each other as well. A low level of differentiation was also shown for the Peter the Great Bay and the East Sea/Sea of Japan waters of the Republic of Korea.

Rethinking the previous studies on <i>the South Kuril Islands Dispute</i> in Russia: analyzing <i>the Northern Territories problem</i> from the perspective of Russian experts on Japanese studies

Rethinking the previous studies on <i>the South Kuril Islands Dispute</i> in Russia: analyzing <i>the Northern Territories problem</i> from the perspective of Russian experts on Japanese studies

Dicranum ignatovii sp. nova (Dicranaceae, Bryophyta) from the Far East

The new species Dicranum ignatovii Tubanova & Fedosov is described from Sakhalin, South Kurile Islands and the Khabarovsk Territory based on the approach of integrative taxonomy. The species is characterized by the unique combination of (1) short leaves with broadly acute apex, (2) slightly recurved distal leaf lamina, (3) short-rectangular to transverse rectangular distal leaf cells, (4) proximal leaf cells abruptly shortened distally and thus occupying only the basalmost leaf portion, (5) costa ending before apex, and (6) presence of flagelliform branchlets in upper leaf axils. Based on nrITS 1, 2 & 5.8 rRNA gene sequences, molecular phylogenetic analysis was carried out. As a result, three studied specimens were found in a well supported clade, nested in a weakly supported clade where D. acutifolium, D. caesium, D. bardunovii, D. angustum, D. bonjeanii, D. scoparium and D. brevifolium were also found.

БИОКЛИМАТИЧЕСКАЯ СИСТЕМА КУРИЛЬСКИХ ОСТРОВОВ, "Известия Российской академии наук. Серия географическая"

The causal mechanisms of the known geographical phenomenon of insular extratropical Neo-Pacific, i.e., the general descent of the boundaries of altitudinal bioclimatic zones and the southward shift of natural zones on islands compared to the neighboring continents, are discussed. The phenomenal feature of bioclimatic system at the stage of insular landscape formation is the direct subordination of phytobiota to vertical hydrothermal gradients. All the above is conditioned by the domination of transpiration part in thermal balance and ensures the survival of insular ecosystems of the boreal Neo-Pacific under unfavorable conditions of cold oceanicity. It is shown that new types of ecological systems of South Kuril Islands arose in the early Pleistocene, when the cover of the wet taiga forests with ancient (Eopleistocene) well-developed soil had been formed that allows us to consider this period the beginning of the evolutionary processes in the vegetation of these islands.

On the genus Ulota (Orthotrichaceae, Bryophyta) in Russia

Specimens of the genus Ulota kept in the bryological herbaria of MW, MHA, LE, NSK, IRK, UUH, VLA and VBGI were revisited basing on the recent taxonomical treatments of the genus in Europe, Asia and North America. Among ten species of the genus previously known from the territory of Russia, U. phyllantha was recently transferred to the new genus, Plenogemma, while Ulota crispa, which has been considered before in the broad sense, was proved to include at least three separate species, U. crispa s. str., U. intermedia and U. crispula; all three species occur in Russia. According to our results, diversity of the genus within North East Asian center (cf. Garilleti et al., 2015) was underestimated. Two new species from the of U. japonica affinity, U. orientalis sp. nov. and U. pacifica sp. nov. are described herein from north Pacific Region (Khabarovsk Territory and South Kurils correspondingly). Thus, at least thirteen taxa of the genus are presently known in Russia; distribution data were significantly corrected for some of them. Key to identification of Ulota species in Russia and adjacent areas is provided; their distribution is discussed and mapped.

Новая карта цунамирайонирования Южных Курильских островов

Новая карта цунамирайонирования Южных Курильских островов

Вихревой апвеллинг как механизм создания благоприятных условий скоплений сайры в Южно-Курильском районе

Вихревой апвеллинг как механизм создания благоприятных условий скоплений сайры в Южно-Курильском районе

Identification and Lagrangian analysis of oceanographic structures favorable for fishery of neon flying squid (Ommastrephes bartramii) in the South Kuril area

Based on the AVISO velocity field, we compute daily synoptic Lagrangian maps in the South Kuril area for the fishery seasons of 1998, 1999, and 2001–2005 from available catching data on neon flying squid (NFS). With the help of drift maps for artificial particles, we found that the majority of NFS fishing grounds featuring maximum catches are situated near large-scale Lagrangian intrusions: tongues of water penetrating the surrounding water of other Lagrangian properties. It is shown that the NFS catch locations tend to accumulate at places where waters with different magnitudes of certain Lagrangian indicators converge, mix, and produce filaments, swirls, and tendrils typical of chaotic advection. Potential NFS fishing grounds are mainly located near (1) Lagrangian intrusions of the Subarctic front, (2) intrusions of Okhotsk Sea and Oyashio waters around mesoscale anticyclones east of Hokkaido with subsequent penetration of catch locations inside eddies and (3) intrusions of subtropical waters into the central part of the South Kuril area due to interaction with eddies of different size and polarity. Possible reasons for increased biological production and fishery in the vicinity of Lagrangian intrusions are discussed.