scholarly journals SEAWALLS IN DEEP SEAS

1980 ◽  
Vol 1 (17) ◽  
pp. 122
Author(s):  
Shoshichiro Nagai ◽  
Shohachi Kakuno
Keyword(s):  
Japan Sea ◽  
Wave Overtopping ◽  
Open Sea ◽  
The Pacific ◽  
The Seto Inland Sea ◽  
The Japan Sea ◽  
The Pacific Ocean ◽  
Under Construction ◽  
A Site ◽  
Good Agreement

Features in wave overtopping of two new types of seawalls designed to be built in considerably deep sea conditions are presented herein. One of those is the seawall of concrete caisson with a parapet wall and armor blocks on the top of the caisson, and another one is the seawall with a slitted box-type wave absorber. The former type of seawall has successfully been constructed in the Japan Sea and the Seto Inland Sea and is also to be constructed at a site directly exposed to an open sea of the Pacific Ocean in 1980 and 1981. The latter type of seawall was proposed in 1977 after numerous experiments and has been under construction in the Port of Osaka since 1978. The results of the experiments on the wave overtopping over the slit-type seawall were compared with the calculated results, obtained by an analysis in which the wave overtopping over a parapet wall was considered similar to the phenomenon of flow over sharp-edged weirs having time-dependent overflow-head. The calculated curves obtained are in good agreement with the experimental results. The designs of these two types of seawall are also presented herein.

scholarly journals AGE RELATIONSHIPS OF RIFTING, SUBDUCTION AND PLUME PROCESSES ON THE EASTERN MARGIN OF ASIA

2021 ◽  
pp. 22-45
Author(s):  
A.M. Petrishchevsky ◽  
◽  
T.A. Emelyanova ◽  
L.A. Izosov ◽  
◽  
...  
Keyword(s):  
Japan Sea ◽  
Time Range ◽  
The Sea Of Japan ◽  
Spatial Distributions ◽  
Southeast China ◽  
Initial Stage ◽  
The Pacific ◽  
The Japan Sea ◽  
Lithospheric Plates ◽  
The Pacific Ocean

Based on the comparison of petrochemical characteristics of volcanics with spatial distributions of rheological heterogeneities in the East Asian tectonosphere, new data on the mechanisms and sequence of subduction, rifting, and plume-type central structures were obtained. Throughout the East Asia transition zone to the Pacific Ocean, subduction began at the initial stage of convergence of lithospheric plates, from 195 Ma in Southeast China to 60 Ma in the Sea of Japan. Subsequent rifting and plume processes have strongly influenced subduction structures. Rifting processes manifested themselves over a wide time range, from 138 Ma to 3 Ma. They can be subdivided into pre-plume and post-plume. Central plume-type structures, accompanied by adakitic volcanism, formed at convergent boundaries of lithospheric segments due to squeezing of the asthenosphere from the mantle by subducting slabs. The age of these structures varies considerably and is 124 Ma in Southeast China, from 37 to 51 Ma in the Okhotsk Sea region, and from 13 to 9 Ma in the Japan Sea region.

scholarly journals Synchrony in the abundance trend of spear squid Loligo bleekeri in the Japan Sea and the Pacific Ocean with special reference to the latitudinal differences in response to the climate regime shift

2013 ◽  
Vol 70 (5) ◽  
pp. 968-979 ◽  
Author(s):  
Yongjun Tian ◽  
Kazuya Nashida ◽  
Hideo Sakaji
Keyword(s):  
Pacific Ocean ◽  
Environmental Factors ◽  
Regime Shift ◽  
Japan Sea ◽  
Climate Regime ◽  
Climate Regime Shift ◽  
The Pacific ◽  
The Japan Sea ◽  
Abundance Trends ◽  
The Pacific Ocean

Abstract Tian, Y., Nashida, K., and Sakaji, H. 2013. Synchrony in the abundance trend of spear squid Loligo bleekeri in the Japan Sea and the Pacific Ocean with special reference to the latitudinal differences in response to the climate regime shift. – ICES Journal of Marine Science, 70: 968–979. Spear squid Loligo bleekeri is widely distributed in the Japanese coastal waters. The fisheries depend largely on four stocks: the southern and northern stocks both in the Japan Sea and the coastal regions of the Pacific. The catch per unit effort (cpue) for the northern stock in the Japan Sea decreased substantially during the 1980s but increased during the 1990s, while the abundance index for the southern stock showed the opposite trend. The cpue for the southern and northern stocks in the Pacific coast showed a similar pattern to that in the Japan Sea. The synchrony in the abundance trends between the Japan Sea and the Pacific Ocean, and latitudinal differences between the northern and southern stocks indicate the impact of the climate regime shift. Generalized additive model analysis identified significant effects of environmental factors. Increased water temperature had a positive effect on the northern stock but a negative effect on the southern stock in the Japan Sea and the Pacific, whereas El Niño–southern oscillation events and the Asian monsoon had additional significant effects on the Pacific stocks. These results suggest that the abundance trends of spear squid were largely forced by environmental factors with latitudinal differences in the response to the climate regime shift.

scholarly journals Evidence of clonal propagation in Cryptomeria japonica D. Don distributed on Pacific Ocean side in Japan

2017 ◽  
Vol 66 (1) ◽  
pp. 43-46 ◽  
Author(s):  
Güliz Doğan ◽  
Takumi Tadama ◽  
Hiroki Kohama ◽  
Asako Matsumoto ◽  
Yoshinari Moriguchi
Keyword(s):  
Pacific Ocean ◽  
Cryptomeria Japonica ◽  
Dna Analysis ◽  
Japan Sea ◽  
Regeneration System ◽  
The Pacific ◽  
Miyagi Prefecture ◽  
The Japan Sea ◽  
The Pacific Ocean ◽  
Strong Winds

Abstract Cryptomeria japonica is distributed on the Pacific Ocean side and reproduces only by seedling; however, C. japonica var. radicans is distributed on the Japan Sea side and reproduces by both seedling and layering. Until now, there has been no report that C. japonica on the Pacific Ocean side regenerates by layering. In this study, the regeneration system of C. japonica in a national forest of Miyagi Prefecture Ishinomaki City was investigated using DNA analysis. C. japonica growing in the study plot was divided into seven genets and 40 single ramets, clearly suggesting that C. japonica at this site regenerates not only by seedling, but also by layering. The strong winds and low temperature appear to be key factors in layering reproduction at this site.

scholarly journals Circulation in the Northern Japan Sea Studied Chiefly with Radiocarbon

Radiocarbon ◽  
2007 ◽  
Vol 49 (2) ◽  
pp. 915-924 ◽  
Author(s):  
T Aramaki ◽  
T Senjyu ◽  
O Togawa ◽  
S Otosaka ◽  
T Suzuki ◽  
...  
Keyword(s):  
Bottom Water ◽  
Deep Convection ◽  
Subsurface Layer ◽  
Japan Sea ◽  
Sea Bottom ◽  
The Pacific ◽  
The Japan Sea ◽  
Current Water ◽  
The Pacific Ocean ◽  
Area North

Radiocarbon concentrations in the northernmost region of the Japan Sea were observed during the summer of 2002. The averaged surface δ14C (above 100 m depth) was 52 ± 8%, which is significantly higher compared with the values of the Pacific Ocean and Okhotsk Sea. The δ14C in the deep water decreased with density, and the minimum value was −70%. By analyzing 14C and other hydrographic data, we found that i) the Tsushima Warm Current Water reaches to the surface layer in the southern Tatarskiy Strait; ii) deep convection did not occur in the northernmost region, at least not after the winter of 2001–2002; and iii) the bottom water that was previously formed in this region may step down southward along the bottom slope and mix with the Japan Sea Bottom Water. Furthermore, a new water mass characterized by high salinity (>34.09 psu) was found in the subsurface layer in the area north of 46°N.

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