Understanding of the global climate system is necessary to clarify the mechanism of the climate change and predict the fluctuations of the global climate and circumstance. Since the sign of these fluctuations can be predicted in the arctic zone where these fluctuations strongly affect the circumstance, the observation in this zone is very important. Observation data to be obtained there, however, are very few and limited due to difficulty caused by a thick ice covering on a wide-ranged area. A conceptual design of a submersible research vessel with a nuclear power source is studied to cope with this difficulty. The nuclear power is suitable for a submersible research vessel specialized to the undersea of the arctic zone, because it enables to operate for a long time without oxide or fuel supply. By taking account of working conditions in observation, the basic specifications of the vessel are decided; the total weight and the length of it are 500 t, 40 m, respectively, and the maximum ship speed is 12 knots. Two sets of nuclear compact reactor, SCR, light-weighted and of enhanced safety are installed in the vessel to supply the total electricity of 500 kW. This vessel is capable of providing a very rapid, fruitful activity in observation and research.
Submarine geological and geophysical surveys in and around the Kii Strait were carried out by two different methods. A single channel watergun method was executed to clarify the fault structures on the shelf in the northern part of the Kii Strait, and a multichannel airgun method was performed to reveal the basement structures of the shelf slope, the Muroto Trough, the outer ridge, the inner trench slope, the Nankai Trough and the Shikoku Basin. The results show that the single channel watergun system is available for the geophysical survey on the shelf in the open sea and the multichannel airgun system is effective for the investigation of deep sea geological structure. Many small faults were detected on the shelf off Tanabe city. They are distributed widely in the shelf area, cannot be recognized as strike-slip faults and are not active in the latest Pleistocene and Recent. Upheaval and subsidence axes trending N-S direction and other upheaval axis trending ENE-WSW direction were recognized in the surveyed area. The last axis was generated later than those trending N-S direction. The provident scarps observed in the northern margin of the Muroto Trough and at the submarine canyons' sides have been proved to be caused not by faulting but by submarine landslides. The outline of the geological structure in the southernmost part of the outer zone of southwest Japan across the outer ridge, the Nankai Trough and the Shikoku Basin has been revealed by this survey.
The formation and depositional environments of the sedimentary sequences on the continental shelf off the Miho Peninsula, Central Japan, are studied in detail on the basis of the geomorphology, surface sediment distribution, and acoustic stratigraphy. Sequential analysis based on seismic reflection records defines an acoustic stratigraphy for the region. Acoustic units are A0, A1, A2 and B in descending order. Units A0, A1 and A2 are considered to be parasequences, and unit B acoustic basement. The boundaries of these units are carefully examined and found to be classified as interpeted to be marine flooding surface (mf), maximum flooding surface (mfs), and major erosional surface (sequence boundary; SB). Studies on internal sedimentary structure of each acoustic unit and sediment distribution pattern shown by the isopach maps clearly indicate major changes in sedimentary environment through these units. A series of isopach map indicates northward and also landward (westward) migrations of depositional centers of the shelf sediments. It is found that these changes in depositional environments are closely related with the sea-level fluctuations during last 18,000 years. Correlation between the acoustic stratigraphy on the shelf and boring cores located on the peninsula provides not only lithological confirmation and environmental constraints on the acoustic units but also time scale for the reconstruction of sedimentary / erosional history of the area. Sea-level analysis on the basis of the published sea-level fluctuation curves for the Tokai and Kanto districts shows intimate relation between acoustic stratigraphy and sea-level fluctuations. Reflectors L, K, J, I demarcate Units, B, A2, A1, A0 on the continental shelf off the Moho Peninsula. Reflector L is correlated with 18,000 yBP, Reflector K with 10,000-9,000 yBP, and Reflector I with 7,500 yBP. These correlations do not conflict with the dating from boring core data. Three stages are proposed in terms of formation of acoustic units and submarine spit platforms on the shelf. By the time of about 10,000-9,000 yBP., The unit B was formed and has been a widespread foundation of submarine spit platforms. About 7,500 yBP., the first and second submarine spit platforms were constructed by accumulation of the A1 and A2 units. After 6,000 yBP., the third submarine spit and the Miho Peninsula were formed by accumulation of the unit A0. Migrations or shifts of the acoustic units are found to be closely related with sea-level rise.
The results of IAPSO Standard Seawater(SSW) comparisons are presented for batches P 70, P 88, P 94, and 13 batches made in 1990's. Except for batches P 70, P 88, P 114 and P 128, the standard deviation (1σ) calculated from the repeated measurements of the same batch of SSW ranges from 0.1×10-3 to 0.3×10-3 in Practical Salinity Scale (PSS) and the difference between label-derived and measured salinity referred to batch P 124 ranged from -1.1×10-3 to 0.9×10-3. The result is consistent with the recent results found in other laboratories. The standard deviations of batches P 70 and P 88 were quite large probably because of the aging effect. The standard deviation of batch P 114 was twice to three times as large as other recent batches without any obvious reason. As for batch P 128, the standard deviation and the difference between label-derived and measured salinity referred to batch P 124 changed remarkably during two years.