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Research paper : Creation of seamless geological map of Japan at the scale of 1:200,000 and its distribution through the web (K. Wakita et al.)−74 Synthesiology - English edition Vol.1 No.2 (2008) Furthermore, interoperation with other information systems will help establish safer society in terms of infrastructure and disaster prevention.In this paper, first we present the outline of seamless geological map and its research scenario, which was designed as Type 2 Basic Research in order to actively promote the development of basic intellectual knowledge of Japan. Then we show how to select appropriate knowledge to provide clear and plain geoinformation to the public. Studies of geological maps can be considered as both Type 1 and Type 2 Basic Researches, because they provide various useful geoinformation by integrating broad range of knowledge such as paleontology, structural geology, stratigraphy, and petrology. However, many recent geological maps tend to be thematically specialized, and are published as basic research report with highly advanced research outcomes, stressing the aspect that they are results of Type 1 Basic Researches. In contrast to this recent trend, we shall describe the methodology and features of seamless geological maps as an example of Type 2 Basic Research, which can create great values for society by integrating broader knowledge including Internet delivery technologies.2 Background and goals2.1 Revision of previous geological maps with recent geological modelsThe fundamental, essential parts in creating geological maps are field surveys and field observations. We conduct surveys at outcrops discontinuously exposed along rivers or in mountains to investigate types of rocks and formations and their structures. Developing geological models from observed data, we speculate on the rock distribution underground that are covered by soil and vegetation. How much information we can get from scant field observation and how precisely we can deduce the underground structure depend on the quality and quantity of geological knowledge and models we have. This “analog visualization” technique of extracting as much information as possible from limited field observations and deducing hidden structure beneath has been developed long before invention of computers.Let us describe the case of Mino area in Gifu Prefecture as a typical example where the neighboring geological maps were drawn based on different geological models. There are four 1:50000 geological maps in this area: “Neo,” “Hachiman,” “Tanigumi,” and “Mino” published in 1964, 1984, 1991 and 1995, respectively[4]-[7]. “Neo” was drawn according to the geosynclinals modelTerm 1, which was predominant in geology before plate tectonics was accepted as a new geological paradigm in the 1990s. The geological division and expression adopted in this map are quite different compared to other maps, which were created based on the accretionary prism modelTerm 2 formed by oceanic plate subduction. Furthermore, other three maps were made according to different geological models developed under the plate tectonics theory: submarine landslideTerm 3 for “Hachiman,” mud diapirTerm 4 for “Tanigumi,” and tectonic deformationTerm 5 for “Mino.” Consequently, geological divisions and expressions of the four maps are different (Figure 1).As shown in the above example, knowledge of historical background and transition of theories may be necessary to effectively utilize geological maps. However, most users know little about past geologic concepts and theories even Geological Model BGeological Model CGeological Model D Geological Model A19641995Geological Map AGeosynclineSubmarine SlidingMud diapirismTectonic deformation19841991Neo HachimanTanigumiMinoGeological Map BGeological Map CGeological Map DOceanic Plateabout 10 kmFig. 1 Changes of hypothesis for formation of geologic bodies in Mino area, Gifu Prefecture.(2)−

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