We have conducted our research on the influence of the eruption of the Kelud Volcano on the Kali Brantas, conservation of the river basin, mitigation of the resulting volcanic and flooding hazards, and development process of the basin. For this purposes, we have made geomorphic land classification maps in the Kali Brantas Basin, utilizing the aerial photographs (scale is around 1/40, 000) and LANDSAT Images which were taken in 1972. The Kali Brantas is located in the eastern part of Java, i. e. easternmost part of the Himalaya-Alps Orogenic Zone. The Kali Brantas originates in Mt. Arjuno and round the foot of the Butac and Kelud Volcanos which are active volcanos, and then pours into the Madura Strait. The southern part of the Kelud Volcano consists of the following geomorphic elements: piedmont gentle slope of the volcano, a slightly hilly area on the gently sloping terrace, valley floor plain, marsh, abandoned river course, steep slope, etc. The Kali Brantas plain consists of the following geomorphic elements: natural levees, back-swamps, a delta, lagoon, sand-spits, etc. Natural levees are developed well around the city of Kediri and the river bed is higher than that of the adjacent plain. The Kelud Volcano has erupted approximately once every 15 years. We have a record of its eruption since 1, 000 years A. D. The eruption in 1919 was especially severe, and about 3, 800×104m3 of “Lahar” flowed down to have killed 5, 100 persons. Due to the eruption in the year 1586, about 10, 000 persons were killed. In order to mitigate the damage by “Lahar” a tunnel for decreasing water in the crater was constructed during the Dutch Colonial period. This drainage tunnel reduced the volume of the water from 4, 000×104m3 to 2, 000×104m3 in 1966. After the construction of the tunnel, the lahar damages decreased. However, aggradation as a result of this eruption reduced the depth of the crater about 50m to destroy the tunnel. Then the tunnel was repaired again. After 1970, thre lowering of the river bed has occured partly because of the construction of dams, particularly the construction of “Sabo” dam for “Lahar” and partly the because of the volcanic eruption. Although the lowering of the river bed decreased the possibility of the flooding, it becomes difficult to take the water for irrigation. In February 1990, the Kelud Volcano erupted again. And a lot of volcanic ash was deposited on the southern slopes of the volcano. The tunnel disappered again. So we must look again for the tunnel. Directly after the eruption, torrential rainfall occurred at the upper reaches of the Brantas River. The erosion in the upper reaches was remarkable and a lot of sand and gravel flowed down to the middle reaches and several reservoirs were burned immediately. In conclusion, we would like to indicate that it is very important to predict the geomorphological changes of the river basin in the case of making development plain of the river basin.
Since the 1960's, a huge quantity of red soil has been carried out to sea onto the coral reefs of the northern part of Okinawa Island, with this being due to development of agricultural land and housing sites. However, the distribution of this red soil has remained unknown. The purpose of this paper is to clarify the distribution of red soil which is sedime nted over the coral reefs at the periphery of Katabaru located on the eastern coast of the norther n part of Okinawa Island, by grasping the degree of contamination based on the relationship between the TM data and the amount of Fe2O3 contained in the red soil. These TM data were observed by LANDSAT on August 10, 1984 and April 15, 1988. As a result, the facts stated below were revealed: (1) There is a high correlation between the interchannel ratio of the TM data (the ratio of the CCT count of band 1 to the CCT count of band 3) and the amount of Fe203 contained in the red soil. Thus, the interchannel ratio is an effective index for analyzing the distrib ution of the sedimented red soil. (2) The distribution of red soil was estimated using the interchannel ratio of the TM data. As a result, a remarkably large amount of red soil was found to be sedimented near the estuary, and other sedimented areas were recognized inside the reef crests and along the coast, as well (3) The distribution area of red soil off the coast of Katabaru was almost identical both in 1984 and 1988. This is consistent with the fact that large-scale construction work, which involved major topographic alterations to the basins of rivers flowing into this area of coast, were concentrated in the period up to and including the early 1980's, and that there was only a small number of construction projects after 1984.
Numajiri Bokusen invented an epochal terrestrial globe made from wood, bamboo nd Japanese paper in 1800 and published details of it in 1855. The globe was similar to a coarse Japanese oilpaper umbrella, and in fact was called the “umberlla-like globe” later. Previously, the author has described the form of this globe. The present paper describes the geometrical features of Bokusen's globe, especially, the shapes of shorelines and national boundaries. The world map on the 1855 globe had obviously been revised since that appearing on the globe invented in 1800, based on the latest information on the shorelines available at the time. Since the Japan Archipelago was set in the center of the world, the axis of the globe was declined at 36 degrees. Therefore, the ground level sinusoidally rounds the globe according to its declination. Lines of latitude were shown every 10 degrees. The interval of the lines of longitude was also 10 degrees. While the value of latitude was written, that of longitude was not shown anywhere on the globe. Between the lines of longitude, marks were inserted every one degree along the equator, resembling the symbol used for railways in recent maps. Despite the lack of a base for the median line of the globe, the base was expected to pass through Ferro Island in the Canary Islands. Thus, it is assumed that values were intended to be written every 10 degrees according to the distance from the Island. The location of the Japan Archipelago at the center, and the declination of the earth's axis seem to have been important political matters influenced by attitudes such as reverence for the Emperor and exclusion of foreigners during the late Edo period in Japan. On this globe, the center of the Japan Archipelago was intended to be just under the zenith, and set at 130°(actual value 132° in recent maps) E and 36 N. This location was selected as the place nearest to Miyako (Kyoto), which is placed at 135°46'E and 35°00'N. On the other hand, Edo is at 139°40'E and 35°42'N (almost equal to 36 degrees) based on values in recent maps. Therefore, the base of latitude at the center of the 1855 map seems to have been unchanged since that on the 1800 globe. If Bokusen used the value of Miyako, the inclination of the earth's axis was set at 35 degrees. On the other hand, the base of longitude was altered to a new location near Miyako. Ne-vertheless, Bokusen could not help including some of the base of the median line of the world maps established in the western Europe. Thus, the center was not set in Miyako, but was moved to the west. Some compass lines drawn from the center were made on assumptions, and some remarks about astronomical phenomena such as sunrise and sunset at the winter/summer solstices and the vernal/autumnal equinoxes were written on these lines and assumed lines. Most of the shapes of the shorelines closely resembled those on recent maps. Although the Australian continent was correctly shaped, the Antarctic continent was not shown. In the Arctic region, the shape of the northern coast of the Eurasian continent was relatively correct compared with that of the North American continent. Especially, the areas in the vicinity of Hudson's Bay and the District of Franklin were obscure, and their shapes were expressed using broken lines. This seems to reflect Bokusen's scientific standpoint, which excluded any uncertainty. Between 80°N and 80°S, the coast lines including Korea and the California Peninsula and other continents were correctly shown. On the other hand, the shapes of national boundaries of inland areas were drawn as rough lines framed by colors including blue, red, violet, yellow and black. Some of the shapes appear to be scribbled. Therefore, the decisions regarding boundaries seem to have been less confident.
Three nannofossil datum planes of the Early Pleistocen e are identified in the cores from subsurface at Irabu Island, South Ryukyus. The result allows for the first time to date the initial sedimentation of the reef-related Riukiu Limestone there. It represents the age (1.2M a) turning from siliciclastics to shallow-water carbonate regime. Implication of this transition time is discussed briefly in relation with both local neotectonis m resulting in the birth of a backarc basin (Okinawa Trough) and regional to global reor ganization of paleoceanographic environments.