Stratigraphic units and their boundaries can be compared to activities and events in PERT (Program Evaluation and Review Technique), respectively. When the time of the final event of PERT is defined to be 0, and where the times of the other events (E) and activities (A) are expressed by their absolute values, equations, E₁≥A≥E₂ and A₁≥E≥A₂ are reduced. On the other hand, the equations where A and E are replaced with G (geologic unit) and B (boundary), respectively, are sufficient only for conformity relation. When dummy units are taken into account, however, the equations are sufficient for other relations, such as unconformity, intrusion and fault. This treatment enable the application of PERT for the geochronology. Obtained results may give important suggestions in order to check relations among geologic units.

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The processing system for LANDSAT data is presented. This system consists of 18 programs, and is implemented on MS-DOS. The development principles of this system are as follows: (1) When a LANDSAT data is processed, the most suitable parameters are frequency decided through the trial and error. Therefore the repetition of same work is often done to find the most suitable parameters. This system is made up to find the most suitable parameters easily. (2) The LANDSAT data are converted to the text file on the hard disk device. (3) The processed images can be saved as the text files.
In this paper, the outline of the LANDSAT data processing system and examples of the processing with this system are presented.

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The increasing availability of Digital Elevation Models and other digital maps for the earth sciences needs a convenient method to show three dimensional data sets on a computer display for intuitive understanding of their relationship. In this paper, we present an ANSI-based C program which can make stereo figures of bird's eye view with color gradient from digital maps. The program can also show these figures one after another as an animation. According to the purpose, colors represent various information such as temperature, geoid height and reflectance. This program enables us to understand relations between DEMs and other digital values of simulation results or remote sensing data, and their time developments. After assembling data on UNIX system, we can easily obtain figures or animation directly without transfering or reconfigurating data, if their format is an array of grid data whose location is the same as DEMs. This program is developed for X Window environment on UNIX system, and supported by X toolkit, Athena Widget sets and some X libraries. The algorithm and architecture of this program are so simple that it does not require specially-installed softwares, peculiar hardwares, or much load on the machine.

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Recently earthquake have caused much damage to such agricultural facilities as canals, farm roads, and small earth dams for irrigation.Especially, small earth dam is an important facility due to its function of supply of irrigiration water.Recently disaster prevention of small earth dams are pointed out.Since the surroundings of small earth dams have been developed, the secondary damage (lives, public works) in lower basin may become serious if such earth dams fail.As the result of the Hanshin Great Earthquake of 1995, 1, 222relatively small earth dam used for irrigation suffered from damage.
To efficiently maintain a large number of earth dams for earthquake disaster prevention, it is necessary to create the data base system for earth dams.This paper describes the data base system of small earth dams for earthquake disaster reduction.
The data base contains the following information:
(1) Structural information (location, height, storage capacity, dam cross section, present embankmand status, etc.) .
(2) Visual information of dam data (Location map, photo, drawing) .
(3) Information of local topology, geology, administrative borders, etc. (Digital national land information) .
(4) Published data of active faults of Japan, and rain intensity of local points (Amedas data) . (5) Information of disaster caused by the past natural disaster.

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