The southern Hyogo area, southwest Japan, is well known to have suffered from a large earthquake occurred during January 17, 1995. Although many active faults are distributed in this area, their orientations (dip directions and dip angles) have not yet been clarified from the geologic field investigations. For this problem, we have constructed the estimation and interpretation methods of fracture orientation through a combination of satellite-image derived lineaments, digital elevation model (DEM) data, and digital geologic map. This method is founded on directional relationship between the derived lineament and the slope produced by the DEM. The lineaments are extracted automatically using the Segment Tracing Algorithm (STA). The advan-tages of the STA are its capability to extract lineaments that parallel the sun's azimuth and those located in shadow areas. Lineament analysis was accomplished by using three types of satellite image : LANDSAT TM, SPOT HRV, and JERS-1 SAR images. At first, the appropriate parameter values used in the STA were determined for each satellite image based on the semivariogram for the gray-levels distribution of the image. It was clarified that most of the estimated fractures have steep dip angles ranging from 80° to 90° and are judged to be reverse fault type. The lineaments extracted from the LANDSAT TM image were found to express appropriately the fracture characteristics of the study area. Azimuthal features of the estimated fractures were common to individual surficial geology. Using the location and orientation of the estimated fracture planes, three-dimensional fracture distribution was visualized. This fracture-distribution model was confirmed to be valid through its relation to the distribution of aftershock hypocenters.
The objective of this study was to map the horizontal distribution of water-bloom, or "Aoko", in Lake Shinji, Shimane Prefecture, using SPOT HRV and concurrent field survey data. Surface chlorophyll-a concentration (C) was adopted as a measure of Aoko amount in lake surface water. Two kinds of empirical algorithms, single band regression and band ratio regression algorithms, were used to estimate C from SPOT HRV and in-situ C data acquired in the morning of October 9, 1997. The C distribution patterns derived from satellite data were compared with aerial photographs taken 1.5 hour prior to satellite overpass. Also, various options to determine path radiance values using "Dark pixel" method were examined. The following results were obtained : 1) Surface suspended solid concentration (SSC) affected the accuracy of the estimated C when single band algorithms were applied, 2) The ratio algorithm using HRV band 1 and 2, after path radiance removal, could reduce the influence of SSC and improved the accuracy of C estimation considerably, and 3) Aoko was found along the north shore of the lake with 4-8 km length, and it covered about 7% of the lake surface.
River water expansion (RWE) into a semi-enclosed coastal bay is one of the important elements for the environmental situation of the bay. In order to know RWE in the inner Kagoshima Bay, 16 images of the Landsat-5/TM band 6 are examined. These images are investigated in relation the tidal situation, the water amount of Amori river, the wind direction and the wind speed. Numerical simulation of tidal residual flow is also performed. The main results are as follows ; i) The river water normally assimilates to sea water in about 4 to 6.5 km off from the mouth of the river. ii) The area of RWE is affected by the wind speed during 17 hours before, especially 9 to 15 hours. iii) The direction of RWE is mainly westwards following the constant sea surface flow. iv) At the western region of the inner bay, the front of river water tends to appear in a form parallel to the north-west coast. v) When the amount of river water is large, it is difficult to distinguish the river water from the surrounding sea water. vi) Numerical simulation qualitatively explains the characteristics of RWE.
For more accurate estimation of multi-substance concentration in the water based on a radiative transfer theory within shorter CPU time, a method based on a four flux model has been developed, and has been studied about it's practicability. The fundamental performance of the method was examined by applying it to simulated image data, in which various cases of three substances to be identified and visible-light bands corresponding to LANDSAT TM data were supposed for the data simulation. The inverse estimation for these cases showed that its accuracy depends slightly on the initial concentrations, indicating that with an adequate initial concentration the inverse estimation can provide the concentration of each substance within 0.07% error. And the influence of the remained atmospheric noise after atmospheric noise calibration had only minor effects on the accuracy in the inverse estimation. Furthermore, the results of the estimation used real Landsat TM data had good agreement with sea truth data.
The optical thickness and Angstrom coefficient of the aerosols over the ocean near Japan were retrieved from the polarization measurements by POLDER on board ADEOS Satellite. The optical thickness over the open sea area in the Pacific Ocean was small (<0.2) whereas that over the Japan Sea and near the Japan islands was large on April 26, 1997. The Angstrom coefficient also showed large difference between over the open sea area and near the land. These results suggest that degree of polarization measurements are useful for retrieving optical characteristics over the ocean.
In order to get a best combination of the thermal infrared bands for Sea Surface Temperature (SST) Estimation, a simulation study is carried out by using LOWTRAN-7 of the atmospheric code with 1350 of parameters. As the results from the simulation study, it was found that longer wavelength region would be better compared to the NOAA/AVHRR Bands 4 and 5 when two bands are selected while 8.34 μm is the most adequate center wavelength when additional one band can be selected in addition to the originally selected two bands. Furthermore, a little bit shorter wavelength would be better compared to the NOAA/AVHRR band 3 when additional one band can be selected in addition to the selected three bands before that. Through the simulation study with LOWTRAN 7, 39.4% of improvement on SST estimation accuracy was achieved compar-ed to the accuracy with NOAA/AVHRR bands.