Geology has basic and applied scientific aspects. A geologic map provides useful information for displaying Earth's scientific features, social activity, and economic activity. Geologic maps traditionally have been expressed by two dimensions. Recently, digital geologic maps are created as the processing technology of computers has improved, and many three-dimensional geologic maps are now created in several countries. In Japan, the database of subsurface information is still advancing, so it is thought that the research of a three-dimensional geologic map may be valuable in the near future. Also, a change of geological information distribution accompanying development of an information technology has brought about expansion and diversification of users. So more intelligent information distribution for the user is needed, without losing high quality. In order to fill the demands of users and to raise the worth of geological information, creation of a three-dimensional geologic map is an effective method. For these reasons, in the future, three-dimensional geological information should be distributed positively. In this paper, the research trends of three-dimensional geologic maps are reviewed, and the challenges and future themes are discussed.

View full abstract

 We have been performing fundamental laboratory tests in order to develop a novel conceptual grout, hereafter called biogrout. Hardened biogrout consists primarily of calcium carbonate or silica, typical cement elements in soil and rock. These compounds can fill the voids and cracks in soil and rock using microbial metabolism. This paper reports some test results for biogrout using calcium carbonate and discusses them. We performed a series of precipitation tests on calcium carbonate in test tubes using soil microorganisms sampled from various parts of Japan, examining the effect of temperature on the precipitation of calcium carbonate when testing. As a result, it was indicated that precipitation of calcium carbonate using soil microorganisms occurred at temperatures ranging from 5 to 35°C. Furthermore, we measured the number of soil microorganisms used in the tests and conducted gene analyses of them. The phases of soil microorganisms before testing were compared to those after testing by determining the number of living soil microorganisms, the highest relative frequency of soil microorganisms, and their attributive taxonomical groups. In consequence, it is possible that fungi such as the Penicillium and Aspergillus species frequently metabolized organic nutrition, and at the same time their number increased via their metabolism.

View full abstract

 The authors investigated two sites where slope failure occurred by The 2004 Niigata-ken Chuetsu Earthquake. The main aim of the investigation was to evaluate the strength of sliding surface by laboratory tests and to estimate the mechanism of slope failure based on the test results and relevant analysis results. Each failure occurred in the gentle (from 15° to 20° dip; parallel to the bedding plane) slope, and the sliding surfaces were developed in the weak layers along the bedding planes which had almost flat shape. According to the laboratory tests on the undisturbed samples, the friction angles of each sliding surface (weak layer) are from 35° to 40° and the cohesions are about 10kPa in unsaturated condition and 0kPa in saturated condition. The slope stability analyses based on the test results reveal that each slope was stable against the ordinary water level change induced by rainfall, while its stability during earthquake was influenced by the ground wetting caused by heavy rainfall just before the earthquake. In addition, the failure mode with a long-distance movement suggested that the strength of the weak layer should have been weakened during the earthquake. The simple shear tests show that the alternating load weakens the resistance of the weak layer. Thus, it is estimated that the gentle dip-angle of the failed slope enhanced the alternating effect of cyclic loading, resulting into strength reduction during the earthquake.

View full abstract

 Some of the natural origin heavy metal is sourced from alteration region accompanied by ore deposits and mineral vein. In this research, we investigate heavy metal contents and leaching ability of hydrothermal alteration zone, targeted on Osaru River basin located in southern part of Hokkaido, Japan. Several hydrothermal alteration zone and ore deposits are distributed in the tributary of Osaru River. A lots of Zn, As, Pb, Cu, Ni-enriched rock samples are observed in hydrothermal alteration region. Although especially high heavy metal contents are observed near hydrothermal alteration area, subsurface soils near alteration region does not reflect on metal-rich chemical composition of hydrothermal alteration zone. High leaching arsenic subsurface soils are detected only downstream part of main Osaru River basin composed of fluvial sediments. The arsenic transport from alteration zone is controlled by secondary adsorption to the metal-oxides, -hydroxides, or the other clay minerals in hydrothermal alteration zone. The arsenic leaching potential from alteration zone to the river depends on alteration aspect and environment, and especially, subsurface alteration zone including ferrihydrite and goethite distributed near riverside have high leaching potential.

View full abstract