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| index | Vol. 48 | 1 | 2 | 3/4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | Japanese Index | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Digital geological map of the Osaka Bay Area
Research group of digital geological map
1997
vol. 48 (1), p. 3-4.
Keywords: digital geological map, Hyogoken-Nanbu Earthquake, Osaka Bay area, the area of specific observation for earthquake prediction
Abstract: The 1995 Hyogoken-Nabbu Earthquake caused great disaster around the Isaka Bay Area. The Osaka Bay area is included in the area of specific observation for earthquake prediction. All of the geological maps Osaka Bay area had been completed and published as 8 sheets. Demand for the geological maps of the Osaka Bay area was increased after the earth quake and these maps were utilized usefully. As every each geologic map was accoumlished independently, the legend and colors of geologic units are not unified among these maps, For the convenience of use, these 8 geological maps have been compliled into a general maps through the process of digitization. The compiled map has the same accuracy as the original maps and is printed on a scale of 1:100,000. Digitized map will be offered near future as CD-ROM with several other data, such as the information of each active fault, topographic data, seismic data, etc.
Digitization of the geological maps of the Osaka Bay Area
Jun-ichi Miyazaki
1997
vol. 48 (1), p.5-12, 2 figs., 13 tables.
Keywords: geological map digital compilation
Abstract: The eight sheets of geological maps 1:50,000 were digitized to compile a geological map of the Osaka Bay Area. This paper describes the applied methods for digitizing the geological maps and compilation of digital files.
Compilation of geological maps of the Osaka Bay Area
Hirohisa Matsuura, Toshikazu Yoshioka, Yoshinori Miyachi and Kiyohide Mizuno
1997
vol. 48 (1), p. 13-16. 1 table.
Keywords: digital geological map, Osaka Bay, Akashi, Suma, Kobe, Osaka-Seihokubu, Osaka-Seinanbu, Kishiwada, Ozaki, Sumoto, digital compilation, Osaka Group, Hyogoken-nanbu earthquake
Abstract: In order to give an overview of the geology of the Osaka Bay Area, highly popurated and attacked by a large earthquake in 1995, geological sheet maps on a scale of 1:50,000 have been digitized and assembled into one digital geological map. Compilation of this new map was made through regional geologica correlation, redivision of geological units, and adujustment of the faults and geological framework of the newly compiled map, correlation of geological units in the mapped area, and new materials added to the digital geological map.
Neotectonic map edited from the digital geological map of the Osaka Bay Area
Toshikazu Yoshioka, Eikichi Tsukuda and Yasuaki Murata
1997
vol. 48 (1), p. 19-22, 1 fig.
Keywords: neotectonic map, Osaka Bay, earthquake, active fault, active flexure, digital geological map
Abstract: A neotectonic map was edited from the digital geological map of the Osaka Bay Area. This map shows active falults and active flexures on the simplified geological map with topographic data, and provides an overview of the neotectonics of the highly populated Osaka Bay area. The mapped area covers the urban area between Osaka and Kobe, where was severely damaged by the 1995 Hyogoken-nanbu earthquake.
Laser-heating 40Ar/39Ar dating system of the Geological Survey of Japan: System outlines and preliminary results
Kozo Uto, Osamu Ishizuka, Akikazu Matsumoto, Hikari Kamioka and Shigeko Togashi
vol. 48 (1), p. 23-46, 13 figs., 7 tables, 6 pletes.
Keywords: Laser-heating 40Ar/39Ar dating, experimental procesure, radiometric datiing, volcanic rock, single-grain dating
Abstract: 40Ar/39Ar dating system has been established at athe Geological Survey of Japan (GSJ). Main emphasis of the system is to date individual grains of minerals and a few milligrams or less of volcanic rocks using a laser-heating technique. The system consists of four parts; argon isotope laboratory, laser extraction system, noble gas mass spectorometer, and operation desk. The great advantabe of the laser extraction system of GSJ is to use the optical glass-fiber and the microscope for the beam path from the laser tube to the sample champber. This combination mades it possible to create various sizes of lase beam up to 4 mm with homogeneous enery distribution focused on the sample surface. It is, thus, possible to homogeneously heat the sample of a few millimeters in diameter. Preliminary experiments on biotite satandards suggest that not only total fusion dating but also stepweise heating experiment of a single to a few grains were successful and gave relialbe ages. Relative age relationships between Sori and FC3 biotite standards are perfectly matched with their existing K-Ar ages. Total fusion dating of one or two grains of two biotites from Neogene volcanic rocks gave consistent ages with the existing K-Ar ages. A weighted mean age for 13 analyses on Muro volcanic rocks (K-Ar age: 14.44±0.16 Ma) is 14.31±0.04 Ma, and that for 7 analyses on Utaosa Rhyolite (2.48±0.02 Ma) is 2.52±0.02 Ma. A stepwide heatin experiment on a millimeter size grondmass grain of a Miocene volcanic rocks (K-Ar age: 9.7±1.6 Ma) was also successful and a very reliable plateau age of 12.09±0.19 Ma was obtainded as a weighted mean of 12 consecutive steps.
Abstracts for Geological Survey Seminar, no. 243. Poster session of the newest geological maps publised by GSJ
1997
vol. 48 (1), p. 47-56.
Abstracts for Geological Survey Seminar, no. 244. Geological buckground of the Hyogoken-Nanbu Earthquake
1997
vol. 48 (1), p. 57-64.
