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11.
Yutaka Yoshikawa Akira Masuda Kenichi Marubayashi Michiyoshi Ishibashi 《Journal of Oceanography》2010,66(2):223-232
Seasonal variations of the surface currents in the Tsushima Strait were investigated by analyzing the monthly mean surface
currents measured with HF radar. Several new features of the surface currents have been found. One notable feature is the
large, complicated seasonal variation in the current structure in the eastern channel of the strait. For example, in the southeastern
and northwestern regions of the channel, southwestward countercurrents are found in summer while southeastward acrossshore
currents are found in autumn and winter. The wind-driven flow (Ekman flow) as well as surface geostrophic currents are responsible
for these complicated variations of the surface currents. To quantify each variation of the flow and current, the wind-driven
flow was calculated from the monthly wind (more precisely, the friction velocity) using the monthly speed factor and deflection
angle estimated in our previous study, and the surface geostrophic currents were then estimated by subtracting the wind-driven
flow from the measured surface currents. It was found that the acrossshore currents are the wind-driven flow, and that the
surface geostrophic currents flow almost in the along-shore direction, indicating the validity of the decomposition of the
surface velocity into the wind-driven flow and the geostrophic currents using the speed factor and deflection angle. A real-vector
empirical orthogonal function (EOF) analysis of the surface geostrophic currents shows a pair of eddies in the lee of Tsushima
and Iki Islands as the first mode, which indicates that the southwestward countercurrents in the eastern channel are formed
primarily by the incoming Tsushima Warm Current. 相似文献
12.
Revision of the first order triangulation in the region disturbed by the Nankaido Earthquake of 1946
Katsuhiko Muto 《Journal of Geodesy》1953,27(3):249-256
Zusammenfassung Nach dem Erdbeden von Nanka?do im Jahre 1946 hat man das Dreiecksnetz I. Ordnung in einem Gebiet von etwa 300 km Umkreis wiederbeobachtet,
und zwar auf 47 Punkten insgeasamt 68 Winkel.
Die letzte Triangulation fand in den Jahren 1885–96 statt.—Nach der Ausgleichung des Netzes wurden Punkverschiebungen bis
zu 1,69 m festgestellt.
Communication présentée à l’Assemblée Générale de Bruxelles en 1951 相似文献
Resumen Después del temblor de tierra de 1946, en Nanka?do, se ha vuelto a observar la red de triangulación de 1H orden en un radio de 300 kilómetros aproximadamente. Los puntos de nuevo observados son 47 y los triángulos 68. La triangulaciín precedente se remontaba a los a?os 1885–96. Después de compensar la red, se han deducido los desplazamientos experimentados por los puntos sobre el terreno, que llegaron a ser de 1,69 metros.
Résumé Après le tremblement de tèrre de 1946 à Nankaido, on a réobservé le réseau de triangulation de premier ordre dans un rayon de 300 km environ. Les points réobservés sont au nombre de 47, et les triangles en nombre de 68. La triangtlation précédente remontait aux années 1885–96. La compensation du réseau effectuée, on en a déduit les déplacements subis par les points sur le terrain, qui importent jusqu’à 1,69 m.
Sommario Dopo il terremoto di Nankaido del 1946, è stata riosservata la rete di prim’ordine entro un raggio di circa 300 km. La precedente triangolazione risaliva agli anni 1885–96. Effettuata la compensazione, il confronto fra l’anticae la nuova triangolazione ha rivelato spostamenti nei vertici ammontanti fino a m 1,69.
Communication présentée à l’Assemblée Générale de Bruxelles en 1951 相似文献
13.
K–Ar ages of the Cenozoic basaltic rocks from the Far East region of Russia (comprising Sikhote-Alin and Sakhalin) are determined to obtain constraints on the tectono-magmatic evolution of the Eurasian margin by comparison with the Japanese Islands, Northeast China, and the formation of the back-arc basin. In the early Tertiary stage (54–26 Ma), the northwestward subduction of the Pacific Plate produced the active continental margin volcanism of Sikhote-Alin and Sakhalin, whereas the rift-type volcanism of Northeast China, inland part of the continent began to develop under a northeast–southwest-trending deep fault system. In the early Neogene (24–17 Ma), a large number of subduction-related volcanic rocks were erupted in connection with the Japan Sea opening. After an inactive interval of the volcanism ∼ 20–13 Ma ago, the late Neogene (12–5 Ma) volcanism of Sikhote-Alin and Sakhalin became distinct from those of the preceding stages and indicated within-plate geochemical features similar to those of Northeast China, in contrast to the Japan Arc which produces island arc volcanism. During the Japan Sea opening, the northeastern Eurasian margin detached and became a continental island arc system, and an integral part of continental eastern Asia comprising Sikhote-Alin, Sakhalin and Northeast China, and the Japan Arc with a back-arc basin. The convergence between the Eurasian Plate, the Pacific Plate and the Indian Plate may have contributed to the Cenozoic tectono-magmatism of the northeastern Eurasian continent. 相似文献
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15.
Besshi-type Cu deposits are strata-bound volcanogenic massive sulfide deposits usually associated with mafic volcanic rocks or their metamorphic equivalents. Although there are numerous Besshi-type deposits in the Sanbagawa metamorphic belt, Japan, their tectonic settings and depositional environments remain controversial because of a lack of depositional age constraints. We report Re-Os data for the Iimori deposit, one of the largest Besshi-type deposits in western Kii Peninsula, in order to examine the robustness of the Re-Os isotope system for dating sulfide minerals in the high-P/T metamorphic belt and to elucidate the primary depositional environment of the Iimori sulfide ores. An 11-point Re-Os isochron plot yields an age of 156.8 ± 3.6 Ma. As this Re-Os isochron age is significantly older than the timing of the Sanbagawa peak metamorphism (110-120 or ∼90 Ma) and a well-defined isochron was obtained, the Re-Os age determined here is most likely the primary depositional age. Despite high-grade metamorphism at up to 520 ± 25 °C and 8-9.5 kbar, the Re-Os isotope system of the Iimori sulfides was not disturbed. Hence, we consider that the whole-rock Re-Os closure temperature for the Iimori sulfide ores was probably higher than 500 °C. As the accretion age of the Sanbagawa metamorphic belt is considered to be 120-130 or 65-90 Ma on the basis of radiolarian and radiometric ages, we estimated the time from the Iimori sulfide deposition on the paleo-seafloor to its accretion at the convergent plate boundary to be greater than 25 Myr. Consequently, the depositional environment of the Iimori sulfide ores was not in the marginal sea, but was truly pelagic. 相似文献
16.
M. A.Bautista T. R.Gull K.Ishibashi † H.Hartman K.Davidson 《Monthly notices of the Royal Astronomical Society》2002,331(4):875-879
We study the nature of the peculiar [Sr ii ] and Sr ii emission filament found in the ejecta of Eta Carinae. To this purpose we carry out ab initio calculations of radiative transition probabilities and electron impact excitation rate coefficients for Sr ii . Then we build a multilevel model for the system which is used to investigate the physical condition of the filament and the nature of the observed allowed and forbidden Sr ii optical emission. It is found that the observed spectrum is consistent with the lines being pumped by the continuum radiation field in a mostly neutral region with electron density near 107 cm−3 . Under these conditions, the observed emission can be explained without the need for a large Sr overabundance. 相似文献
17.
Takeshi Naganuma Masanori Kyo Tatsuhiko Ueki Kazuhiko Takeda Jun-ichiro Ishibashi 《Journal of Oceanography》1998,54(3):241-246
A new hydrothermal fluid sampler has been developed to provide more maneuverability in underwater operation. The sampler characteristically
employs a shape-memory alloy, which senses high temperature and actuates the suction mechanism. A shape-memory alloy is also
used to switch the intake valve of the sampler, the intention being to avoid missampling when the inlet is in low temperature
water. Prototype samplers were designed to collect the fluids hotter than 80°C. Test sampling was performed at hydrothermal
vents (1372–1374 m deep) in the submarine volcano, Suiyo Seamount, Izu-Bonin Arc, northwestern Pacific. Observed fluid temperature
was between 138 and 298°C, while the ambient seawater temperature was 3.1°C. Each prototype collected about 100 ml fluid as
designed. The magnesium concentration in the samples indicated a seawater content of 47.5–90.8%, which indicates the entrainment
of ambient seawater. Microscopic observatinn revealed the occurrence of microorganisms in the sample fluids at a population
density of 105 to 106 cells ml−1, which is 2–3 orders of magnitude higher than those in seawater at that depth. The use of the newly developed fluid sampler
will greatly facilitate the collection of vent-associated microorganisms, which are of potential biological and biotechnological
interest. 相似文献
18.
Estimation of elastoplastic deformation around an underground opening induced by the excavation of it, especially displacement and strain field in plastic region, is presented in this paper, as well as the formulation for calculating the displacement and strain in the plastic region around the underground opening by the coupled Boundary Element Method - Characteristics Method (BEM-CM). In this method, the non-associated flow rule is adopted to calculate the displacement and strain field in the plastic region, which is determined by the integration of the displacement along characteristics lines under the boundary condition of the elastic displacement on an elastoplastic interface analysed. It is shown that this method is one of the accurate and effective methods for estimating not only the shape and extent of the plastic region but also the state of the displacement and strain in the plastic region around the underground opening, comparing the theoretical solution with numerical results by this method for a circular opening under hydrostatic initial stress condition. Furthermore, this method is applied to rectangular and horse-shoe shaped openings and the characteristics of the strain field in the plastic region are discussed. © 1997 by John Wiley & Sons, Ltd. 相似文献
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