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Research paper−74−Synthesiology - English edition Vol.9 No.2 pp.­­­74–86 (Sep. 2016) is easy to use from the viewpoint of the users” was discussed, and it was proposed that a geoinformation organization considering secondary useTerm 1 would be promoted in the Intellectual Infrastructure Plan. Based on this plan, AIST set the data of the drilling surveys that it originally conducted as standards, conducted a wide range of strata correlation using the borehole data of public works and others disclosed by the local governments, and engaged in research for analyzing the 3D distribution of strata by computer processing for the urban areas. We are working on a method that allows anyone to browse and use such a 3D geological model on the web, as well as construction of a system that also allows browsing and use of the original borehole data used in 3D analysis. In this paper, we introduce our efforts on geoinformation organization for urban areas. 2 Awareness of the current situationRecently, data of drilling surveys conducted in the public civil engineering and construction projects are being disclosed on the websites as database because there is increased awareness that geoinformation is important. Tokyo Metropolitan[3] and Chiba Prefecture[4] have disclosed their borehole data from an early stage, and the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) has started to disclose the borehole data of national projects.[5] A portal site that allows browsing such databases was developed by the National Research Institute for Earth Science and Disaster Prevention.[6] In accordance with the recent Government’s open government data strategy, the local governments are also enthusiastic in disclosing borehole data. However, these borehole databases that have been prepared so far simply 1 IntroductionThe 2011 Off the Pacific Coast of Tohoku Earthquake brought about serious tsunami damage, and also caused liquefaction of the ground occurred in some coastal and riverside areas in Chiba and other places.[1] In this earthquake, there were not much residential collapse caused by the seismic motion despite the magnitude of the earthquake, yet there was much damage of falling roof tiles in the Tohoku and Kanto regions. According to a study in the Tsukuba and Tsuchiura areas, the distribution of the damage was very distinctive.[2] Such damage depends on the epicenter, magnitude, and characteristic of the seismic wave such as the dominant frequency, but are also greatly affected by geological conditions of the area. The general public became aware to some extent of this fact through the mass media, and their interest in geology has increased. Also, geological survey is essential for civil engineering and construction works, and if one can obtain prior information of the geology on which the construction will take place, the planning and estimation of the geological survey can be done easily and the process of actual construction may go smoothly. However, the current methods of understanding the subsurface geological condition of the urban plain areas are not sufficient.With this background, in the Phase II of Measurement Standards and Intellectual Infrastructure Plan of the Ministry of Economy, Trade and Industry (METI) for 2013, we decided to work on the organization of geoinformation of the urban areas through the integration of borehole data as our priority issue. In the “Special Committee on Measurement Standards and Intellectual Infrastructure,” the “use of a new intellectual infrastructure that can be easily understood and —New style of geoinformation in an urban area—Although geoinformation pertaining to urban areas is very important, paper-based geological maps do not adequately describe the subsurface geological conditions of urbanized plains. A three-dimensional geological map, available via the Internet, is expected to provide intelligible, highly reliable, and easily utilizable geoinformation for urban areas. In this case, a three-dimensional geological model needs to be constructed on the basis of reliable borehole data using an advanced modeling tool. We are now developing a prototype of a three-dimensional geological map of the northern part of Chiba Prefecture as a new form of urban geoinformation which contributes to estimating the risk of geological disasters.Three-dimensional urban geological mapKeywords : Geoinformation, three-dimensional geological model, borehole data, subsurface geology, geological map[Translation from Synthesiology, Vol.9, No.2, p.73–85 (2016)]Tsutomu Nakazawa*, Susumu Nonogaki and Yoshinori MiyachiResearch Institute of Geology and Geoinformation, AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan * Original manuscript received August 31, 2015, Revisions received October 22, 2015, Accepted October 26, 2015

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