• Geophysics and Geophysical Exploration
• /
• v.13 no.3
• /
• pp.198-202
• /
• 2010

In and around the Korean Peninsula, 18 intraplate earthquake focal mechanisms since 1936 were analyzed to understand the characteristic of focal mechanism and regional stress orientation and tectonics. These earthquakes are largest ones from the last century and may represent the characteristics of earthquake in this region. Focal mechanism of these earthquakes show predominant strike-slip faulting with small amount of thrust components. The average P-axis is almost horizontal ENE-WSW direction. This mechanism pattern and the direction of maximum stress axis is very similar with northeastern part of China and southwestern part of Japan. However they are quite different with the eastern part of East Sea. This indicate that not only the subducting Pacific Plate from east but also the indenting Indian Plate controls focal mechanism in the far east of the Eurasian Plate.

• Journal of Ecology and Environment
• /
• v.35 no.4
• /
• pp.359-365
• /
• 2012

We investigated leaf disease intensity of Kalopanax septemlobus (prickly castor oil tree) caused by the parasitic fungus Mycosphaerella acanthopanacis, in thirty natural host populations in the Japanese Archipelago. The disease intensity observed for individual trees were analyzed using a generalized additive model as a function of tree size, tree density, climatic terms and spatial trend surface. Individual tree size and conspecific tree density were shown to have significant negative and positive effects on disease intensity, respectively. The findings suggest that the probability of disease infection is partly determined by dispersal of infection agents (ascospores) from the fallen leaves on the ground, which can be enhanced by aggregation of host trees in a forest stand. Regional-scale spatial bias was also present in disease intensity; the populations in northern Japan and southern Kyushu were more severely infected by the fungus than those in southwestern Honshu and Shikoku. Regional variation of disease intensity was explained by both climatic factors and a trend surface term, with a latitudinal cline detected, which increases towards the north. Further research should be conducted in order to understand all of the factors generating the latitudinal cline detected in this study.

• Journal of Environmental Science International
• /
• v.24 no.7
• /
• pp.893-905
• /
• 2015

This study analyzes the correlation between Western Pacific (WP) teleconnection pattern index (WPI) in April during 1954-2008 and rainfall amounts in the same month. Based on the results, it is identified that there have been strong positive correlations between central China, Korea and the southwestern part of Japan in the East Asian region. Through differences between 10 positive WP years and 10 negative WP years selected from the April WPI excluding ENSO years, it is found that rainfall amounts increase in April of positive WP years due to the following characteristics. Increases in rainfall amounts are evident in the East Asian middle latitudinal region where the positive correlation between the two variables is the highest and this is because anomalous southwesterlies are strengthened in the East Asian middle latitudinal region due to the spatial pattern of a south-low-north-high anomalous pressure system centered on this region that is made by anomalous anticyclones centered on the southeastern side of the region and other anomalous anticyclones centered on the northeastern side of the region. In addition, anomalous westerlies (jet) are strengthen in the upper troposphere of the East Asian middle latitudinal region and as a result, anomalous upward flows are strengthened in this region and thus anomalous warm air temperatures are formed in the entire level of the troposphere in the region. In addition to atmospheric environments, anomalous warm sea surface temperatures are formed in the seas in the East Asian middle latitudinal region to help the rainfall amount increases in the East Asian middle latitudinal region.

• Journal of Environmental Science International
• /
• v.22 no.10
• /
• pp.1363-1371
• /
• 2013

In this study, we estimate the interannual spatial and temporal distributions of fishing grounds at night in the East Sea based on satellite and in-situ data. We observe that the $15^{\circ}C$ thermal front moves in the north-south direction according to the movement of the warm water (above $18^{\circ}C$) in the Tsushima Warm Current (TWC) area, forcing the cold water area (below $10^{\circ}C$) to either expand or shrink. The interannual variations of sea surface temperature (SST) in winter represented by the indicator SST of $6^{\circ}C$ are consistent with the east-west zonal areas in the central East Sea which represented over $1^{\circ}C$ standard deviation of SST in February during 1990-2000. Annual SST in the fishing grounds of common squid fishing vessels, observed both by fishing vessels and satellites range from 9-$22^{\circ}C$, with the satellite-observed data having a larger range than the fishing vessel-based ones. The interannual distributions of the common squid fishing grounds in the East Sea are mostly concentrated in the TWC area in the southwestern part of the East Sea and in the coast of southern Honshu and Hokkaido in Japan. The interannual distributions of the nighttime fishing vessels are consistent with the catches investigated from the fishing vessel.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.21 no.3
• /
• pp.139-144
• /
• 1988

The vertical distribution of eggs and larvae of anchovy. Engraulis japonica were studied based on ichthyoplankton and the temperature distribution in the southwestern part of the Sea of Japan off Korea during the summer of 1985 and 1986. Thermoclines occurred at the surface layer in the coastal area and at the sub-surface layer in the offshore area in the early summer of 1985. However, they occurred at the surface layer throughout the summer of 1986. Anchovy eggs and larvae were abundant in the offshore in 1985 and in the coastal area in 1986. It seems that the spawning ground of anchovy in 1985 shifted to the offshore owing to the sloping of thermoclines. According to the distribution layer of anchovy eggs by developmental stage, the eggs in the early developmental stage were abundant at $0\~30m$ layer about 06:00. But the eggs in the late developmental stage were abundant at $30\~100m$ loom layer about 24 : 00. These results suggest that anchovy spawn at the $0\~30m$ layer at night and eggs tend to sink to the $30\~100m$ layer in the course of development.

• 한국해양학회지
• /
• v.25 no.1
• /
• pp.36-48
• /
• 1990

This study was carried out to obtain some informations on the species composition and distribution pattern of Polychate community on the continental shelf and slope area in the East Sea. Fauna samples were collected from three sampling cruises in April of 1985, and April and October of 1987. Total 112 polychaete taxa included in 36 families were collected. Dominant species in the study area were Chaetozone setosa, Aglaophamus malmgreni, Ampharete arctica Terebellides horikoshii, Tharyx sp., and Magelona pacifica. Northern and cold water species were major contributors of polychaete communities in this study area. Dominant species showed their specific depth ranges from shelf area to upper slope and middle slope depth. The overall density was 300 indiv./m$\^$2/ and species richness was around 12 species/0.2m$\^$2/. Significant changes in mean polychaete density and species richness along depth gradient were found approximately at 600 m or deeper depth. Among physical factors, water depth, temperature and clay content, mean grain size were significantly correlated with the mean density of dominant species.

• Economic and Environmental Geology
• /
• v.13 no.1
• /
• pp.1-19
• /
• 1980

The local earthquake data, observed by Wiechert seismograph in Korea during Feb. 1926-May 1943, was provided and investigated. Using S-P monogram of JMA, mainly Tsuboi's formula and additional intensity data, the earthquake parameters are obtained as much as possible within a reasonable discrepancy. The seismic characteristics as to the epicenter distribution was discussed under the viewpoint of its relation to the adjacent geologic structure. Some statistical results are analyzed comparing with Kyushu region which provide a reasonable interpretation on the seismicity of Korea. By superposing the available information of the individual events, the general trend of stress field was found to be east-west compression, which mostly agree with that of the southwestern Japan.

• 한국해양학회지
• /
• v.21 no.3
• /
• pp.146-155
• /
• 1986

Zooplankton samples of upper 50m layer in May, 1985 and of various depth intervals depending on thermal structure in October, 1985 were analyzed. Standing stock represents mean of 538inds/㎥ in spring and 267 inds/㎥ and 508inds/㎥ of whole column mean and surface layer in fall, respectively. A total of 55 and 104taxa is identified in each season and accumulated data list at least 123 species inhabiting in the study area. Copepods dominate in the zooplankton community, followed by protozoans and appendicularians in both seasons. In surface layer, distribution of subtropical species and standing stock seems to illuminate the effects of the Tsushima Current and the North Korean Cold Watermass in cold season, whereas only standing stock shows discernable variation in warm season. Concerning whole water column, depth of permanent thermocline bottom, at about 120m in fall 1985, plays significant role as a barrier to the distribution of mesopelagic cold water species. Serial sampling in October, 1985 does not reveal any perceivable diel vertical migration, which is considered to confirm the earlier suggest that owing to the lack of true abyssal species zooplankton biomass of deeper gayer is very poor, so that diel vertical migration of the East Sea is weak.

• Korean Journal of Plant Taxonomy
• /
• v.47 no.4
• /
• pp.316-321
• /
• 2017

Tectaria fuscipes (Wall. ex Bedd.) C. Chr. (Baek-Rok-Go-Sa-Ri) is newly reported in Korea. This species belongs to the genus Tectaria Cav. of the family Tectariaceae Panigrahi. Thus far, no taxa of Tectariaceae have been reported in Korea. Tectaria fuscipes is characterized by its suberect to ascending rhizome, dimorphic or subdimorphic fronds, and free veins. The species was found on the southwestern slopes of Mt. Halla on Jeju Island, where it grows in sun near a small cave. It also occurs in southern China and in Taiwan. In Japan, eight species of the genus Tectaria have been reported, but T. fuscipes has yet to be recorded there. Jeju Island is the northeastern-most limit of the known range of this species.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.33 no.1
• /
• pp.30-37
• /
• 2021

The Annals of Joseon Dynasity record a significant damage of tsunami in the east coast of Gangwon Province on August 29, 1741. The tsunami occurred near Oshima-Oshima island off the southwestern coast of Hokkaido, Japan, and this study conducted simulations of a ray-tracing model to analyze the effects of the tsunami on the East coast of Korean Peninsula at that time. Model results were calculated using four different depth dataset (ETOPO2m, ETOPO1m, SKKU1m, and GEBCO15c), and results using the highest resolution GEBCO15c showed the best description of the damage recorded in the Annals of the Joseon Dynasty. Based on such, the travel time and paths of the tsunami that reached the main regions of Gangwon Province are presented in detail.