The floor structure in Korean folk housing can be classified into three types such as the ondol floor, the dirt floor, and the wooden floor. Among them, the ondol, which is the traditional floor heating system in Korea, becomes a common element to be used in the bedroom. On the other hand, the wooden floor is not necessarily an indispensable element, although it is given an important position in the middle or the large size house. This wooden floor has been i hought to have been developed as the living space for summer life especially in the southern part, and to have been originated from the raised floor construction, or the pile dwellingso-call ed, in the southern culture. In fact, however, we can observe some different tendency there. Major points of the regional characteristics of wooden floor rooms in Korean houses are summarized as follows : South of the central part of the Korean Peninsula, the wooden floor part occupies actually a considerable area in the whole floor of the house. It is rather in the central part, however, that the wooden floor room is used as an open living space for summer life. On the contrary, one can often observe it to be used only as a closed storeroom for grain and a sacred space for household deity in the southern part where it gets hotter and more humid in summer. In Cheju island, located south of the southern coast of the Korean Peninsula, the wooden floor room becomes a living space as well as in the central part. The name of the wooden floor room and its use for ritual ceremony in Cheju houses, however, differ obviously from those in the central part. Moreover, the floor height of wooden floor room is considerably lower in Cheju Island than in the main land. Therefore, it seems difficult to identify the wooden floor rooms in all part of Korea uniformly with the original raised floor construction in the southern culture. In Cheju Island, where the ondol system was introduced much later than the main land, the wooden floor room may have been established as a partial conversion of the original dirt floor dwelling but not as a traditional way of the pile dwelling in the southern culture. On the other hand, the raised wooden floor room in the main land may be supposed to be developed in the floor plan through the rising process of the floor accompanied by the introduction of the ondol system which has underfloor flues through which the hot smoke flows.
Pliocene molluscacn fauna and its paleoenvironmental setting of Matsunoyama-machi, Niigata Prefecture, are important for considering succession from Miocene to Plio-Pleistocene shallow sea faunas in Japan Sea borderland as well as considering paleoenvironmental change in the northern Fossa Magna Region. Pliocene deposits in the southeastern flank of Matsunoyama Anticline consist of the Kurokura, Higashigawa, Ikenosawagawa, Arikurayama formations from lower to upper. In the northwestern flank, the Higashigawa formation is conformably covered with the Naradate. Every formations is in conform able relation involving partial development of a contemporaneous heterotopic facies relation. Many cold-water species are included among Pliocene molluscan fauna in this area. Only a few horizons yielding warm-water species are recognized in the Higashigawa and the Ikenosawagawa formations. Seven associations are discriminated in the molluscan faunas of this area. Based on the faunal analyses, it has become clear that this area was in an upper bathyal zone in the Early Pliocene, and the sea became shallower subsequently. In the middle Pliocene, the area in the southeastern flank of Matsunoyama Anticline was in an embayment-tidal zone, whereas that in the northwestern one was in an upper sublittoral zone.
From the overall analyses of the data from Synthetic Aperture Radars (SARs) on Japanese Earth Resource Satellite-1 (JERS-1/JSAR) and ESA Remote sensing Satellite-1 (ERS-1/AMI), the data from the high resolution optical sensor on French earth observation satellite (SPOT), and the truth data acquired on the ground, the interesting results about the ice cover on Lake Saroma and the sea ice in the Sea of Okhotsk were obtained as follows : (1) Backscatter ranges for the ice cover on Lake Saroma were -10.2 to -5.0 dB for AMI and -17.7 to -13.6dB for JSAR at the sampling sites. The ice on Lake Saroma was classified byusing HRV data and the visual observation from the boat, then the backscatter intensity for each ice type was confirmed. (2) A method for making a mosaic image using SAR data was developed and demonstrated. Comparing JSAR and AMI mosaic images at the same area, it was found that JSAR can clearly discriminate the sea ice and the open water, while AMI cannot distinguish them. The reason of this difference is supposed to be difference of frequency and incidence angle. (3) When the ice becomes thicker, the backscattering intensity decreases in AMI data. It is estimated that the backscatter changes corresponding to the dielectric constant for ice, which is related to the ice surface temperature.
The chemistry of ferromanganese oxides coating pumice gravels and muddy sediment cores taken by the Research Dive 134 of the submersible “Shinkai 6500” from the oceanward slope of the Japan Trench off Miyako, Iwate Prefecture, are described. The ferromanganese coatings are quite thin and are poor in heavy metal elements including Fe and Mn, compared with previously reported ferromanganese nodules and crusts, from the seamounts and ridges in the Japan and Ogasawara Trenches. In the Fe-Mn- (Cu+Ni+Zn) × 10 ternary plot, the published ferromanganese nodules and crusts fall on a typical hydrogenous region, but the ferromanganese coatings in this study lie between hydrogenous and oxic diagenesis regions. This suggests that the former were formed by direct precipitation of colloidal metal oxides from seawater, while the latter grew by elemental supply both from pore waters in the underlying sediments and by the direct precipitation of colloidal particles. The differences of the accretionary process in the ferromanganese oxides from some of the trench areas, are caused by local environmental variations, related to the topography and sedimentary conditions including bottom currents.
We show that seismic activity decreased clearly in a wide area before the 1953 Boso-oki earthquake and the 1972 Hechijojima-toho-oki earthquake. In both cases the seismic quiescence extended to the Tokyo Metropolitan area. Marking precursory activity appeared several years before the Boso-oki earthquake in the Chiba prefecture and in the sea region off-Ibaraki prefecture. It is also noted that the seismicity in the Kanto region as well as in the sea region south off-Boso Peninsula decreased conspicuously after the Boso-oki earthquake. On the contrary an increase of the seismicity was observed after the Hachijojima-toho-oki earthquake, although deep seismic activities decreased remarkably. We show that seismic quiescences preceding the Boso-oki earthquake and the Hachijojima-toho-oki earthquake were detectable before their occurrences, and no other statistically significant quiescence has appeared in the south off-Kanto region since 1926. It is proposed that the occurrence of a large earthquake may be predicted by monitoring changes of the seismicity in a wide area.
The cracks on the sea bottom in the middle of the oceanward slope of the northern Japan Trench off Miyako, Iwate Prefecture, in the depth of 6, 280-6, 210 m, were revisited during Research Dive 134 of “Shinkai 6500”, in July 1992. Mapping and observation including previous dives, 65, 66, 67 and 130 revealed the distribution, features and characteristics of the cracks. The cracks developed at the flank just above the steep cliffs, paralleling the main N-S trending trough of a horst-and-graben structure in the descending Pacific plate. The cracks have several meters depth and height, and are more or less straight, and continue for several tens of metres to several hundreds of metres. The predominant directions are either N-S or N20°E. Cracks are open, and not dislocated but stretched horizontally. Often they are branched into a Y-shape before merging again. Some are arranged in an en echelon fashion. A pressure ridge which was formed by compression of the previously open crack was found. Sediments in and around the cracks are soft, poorly indurated siliceous biogenic clay or claystone, and contain considerable amount of volcanic ash. Pebbles with manganese coating are abundant particularly in and around the cracks, suggesting the presence of oxidized bottom currents. The bottom current eroded the superficial part of the sediments exposing fracture cleaved mud below. Sediments that are rich in clay minerals indicate cohesion. However, if the slope suffers induced differential stress, the sediments may open up horizontally forming cracks or extensional fracture cleavages. This differential stress may be attributed to horizontal shaking during an earthquake, associated with the normal faulting of a horst-and-graben structure. Such an earthquake occurred underneath the study area on March 3, 1933, Magnitude 8.4.