There are three stages in metal exploration, namely reconnaissance survey, regional survey and detailed survey, among which there are not significant differences in the utilized geophysical methods. This means magnetics, gravity, DC resistivity and electromagnetics are the most considerable geophysical tools irrespective of mineralization types in metal exploration.
 IOCG, porphyry copper, SEDEX and orthomagmatic deposits can be listed as the most important metal resources in the world mining industry.
 IOCG is the large-scaled disseminated deposit which produces copper and gold accompanied by considerable amount of iron oxide minerals. Gravity and magnetic methods are the most effective tools for IOCG geophysics because iron oxide and copper minerals are typically much denser and magnetite has much larger magnetic susceptibility than the unaltered host rock minerals. Although the resistivity data by IP and electromagnetic method might have a difficulty in delineating disseminated IOCG-mineralized zones as low resistivity parts, these are capable of detecting massive sulphide parts and the second enrichment zones as low resistivities. However, the high chargeable feature of IOCG ores irrespective of the type of IOCG mineralization enables the chargeability data by IP to depict IOCG-mineralized zones as high chargeability parts.
 Porphyry copper deposit has an extensive dimension with disseminated mineralization related to porphyry. Potassic alteration zone might be delineated as the potassic anomaly caused by its high potassium content by radiometoric method, and might be detected by the high magnetic anomaly if the potassic alteration includes abundant of magnetite. DC resistivity and electromagnetic methods might be able to outline the mineralized and hydrothermal-altered zones as low resistivities. IP is the most utilized tools in porphyry copper exploration because copper sulphide has high chargeability independently of mineralization characteristics.
 SEDEX is the large-sized lead-zinc deposit hosted by the sedimentary horizons including shale and carbonate in which metal sulphate can be reduced in the mineralization process. Magnetic and gravity methods are instrumental tools to delineate the possible conduits associated with the hydrothermal activities. In the detailed survey, IP is an important tool to depict mineralized-zones as high chargeability parts. Electromagnetic method might be workable in delineating the massive mineralization.
 Orthomagmatic deposit is formed by magmatic fractional crystallization, whose dominant metallic minerals are nickel sulphide, chalcopyrite and platinum metals. Because it is typically situated inside mafic rocks and/or at its contact with the adjacent rocks, magnetic methods might be a useful tool in delineating the mafic rock distribution. DC resistivity and electromagnetic methods are able to depict mineralized-zones because nickel sulphide mineralization typically takes on the massive-characteristics.

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 This paper presents an optimization of multiple attenuation including three-dimensional Surface-Related Multiple Elimination (3D SRME). First of all, using marine 3D seismic data, we tested 3D SRME in terms of interval distance of the Multiple Contribution Gather (MCG) and the aperture parameter. The aperture parameter defines the ellipsoidal area for producing MCG. It is found that the optimal MCG interval is same as CMP interval and the aperture parameter should be set to the length that the ellipsoidal area includes neighboring sail lines. Moreover, the strategy of the aperture parameter presented in this paper will offer an optimized quality of 3D SRME. Subsequently, we conducted the comparison of 3D SRME and PRT. According to our results, 3D SRME performed better than PRT in near- to middle-offset records and effectively worked under circumstances where the diffracted multiple was observed or the difference of RMS velocity between primary and multiple reflection was small. Moreover, 3D SRME is expected to contribute to increase the accuracy of such cascaded processes as deconvolution or velocity analysis since it can be applied to the field-data. On the other hand, PRT showed superiority to 3D SRME on the far-offset records; therefore, it is considered advantageous for deep subsurface imaging. In conclusion, the implementation of PRT after 3D SRME can produce the best results owing to complementary attributes of each method.

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 A 3D S-wave velocity model for the Kanto sedimentary basin, Japan, is reconstructed using 1D structure data by the results of microtremor array explorations. This new model is reduced the presumption region with compilation added new explorations in the northern part of Kanto plain in the target model area. Then we simulated the long-period ground motion during a moderate earthquake of near the Izu-Oshima in 1990 using the basin 3D model. This new model was able to explain the ground motion records during the target earthquake as same as the previous one, and it led to the improvement of the reproducibility of the observed waveform in not only the area around Tokyo Bay but also the other parts in the plain. Especially, the effect of regional distribution of the S-wave velocity in the top layer of the basin model was investigated. Especially, the necessity of careful consideration was pointed out in modeling the top layer with low velocity and thin in case of finite difference modeling for long-period ground motion.

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 Magnetic susceptibility anomaly was found in faults. Magnetic susceptibility in fracture zones was often higher than that in non-fracture zones. In faults, in addition, anomalous low gamma-ray dose was often observed. To confirm whether the factor that increases magnetic susceptibility can be used as an index of the gamma-ray screening effect, the gamma-ray attenuation experiment was conducted. The gamma-ray absorption increased corresponding to grain refining and high FeO content that increases magnetic susceptibility. Therefore, the decrease in the gamma-ray dose in the fault is attributed to the screening effect associated with high magnetic susceptibility in the fracture zone in some cases. Change of magnetic susceptibility is caused by change of magnetic mineral such as grain refining, density increase, weathering, and alteration. The mechanism of forming gamma-ray anomaly in the faults appears to differ among different faults depending on the magnetic characteristic of the fault material.

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 We carried out a series of seismic surveys at the coastal land area of Horonobe district, Hokkaido to clarify subsurface structure of the shallow zone around Horonobe town located at the west coast of northern part of the Teshio plain. The series of surveys included a P-wave reflection survey targeting relatively shallow zone and an S-wave reflection survey targeting extremely shallow zone. We interpreted subsurface geological structure by comparing the seismic survey results with the borehole data acquired in a borehole drilled at the research area. P-wave reflection survey clarified that each Quaternary to Neogene layer thickly deposited at west end of survey line makes deposition depth shallower while making its layer thickness rapidly thinner toward the Sarobetsu fold located at the eastern part of a survey line. S-wave reflection survey clearly images two major reflection events. The former one is the reflection from the boundaries between nearshore sediments and lower sediments at the depth range of about 30-40 m. The lower sediments are composed with clayey to silty deposits at the most part of the survey line, and with lagoon deposits at the central part of the survey line. The latter one is the reflection from the basement of the alluvial deposit at a depth of about 80 m. From those results, we can conclude that we revealed the sedimental environment of approximately the last 10,000 years in detail.

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 Because of the large detector volume that can be deployed, ground-based detectors remain state-of-the-art instrumentation for measuring high-energy galactic cosmic-rays (GCRs). This paper demonstrates how useful information can be derived from observations of the directional anisotropy of the high-energy GCR intensity, introducing the most recent results obtained from the ground-based observations. The anisotropy observed with the global muon detector network (GMDN) provides us with a unique information of the spatial gradient of the GCR density which reflects the large-scale magnetic structure in the heliosphere. The solar cycle variation of the gradient gives an important information on the GCR transport in the heliosphere, while the short-term variation of the gradient enables us to deduce the large-scale geometry of the magnetic flux rope and the interplanetary coronal mass ejection (ICME). Real-time monitoring of the precursory anisotropy which has often been observed at the Earth preceding the arrival of the ICME accompanied by a strong shock may also provide us with useful tools for forecasting the space weather with a long lead time.

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[in Japanese]

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