Two types of geotomography techniques, seismic tomography and resistivity tomography, were reviewed and experimentally applied to the foundation rock investigation at a dam site. The target area was a vertical section defined by test adit and boreholes excavated at the site. Previous drilling investigations revealed the existence of a weathered layer and a complex series of faults within the section.
The distribution of P wave velocity within the section was reconstructed by seismic tomography. The weathered layer and faults showed up as low velocity zones. The image reconstructed from resistivity tomography showed the weathered layer and faults as high and low resistivity zones, respectively. In addition, it was found that the condition of rock could be appropriately estimated by interpreting the results of both seismic and resistivity tomography together.
In the future, it is expected that geotomography will provide useful information for elucidating complex geological structures.

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In order to evaluate the phenomena of masstransportation by groundwater flow in granitic media, it is necessary to make clear geological, hydrogeological and geochemical characteristics of fracture distributed in rock mass.
Characteristics of fracture pattern, fracture filling material and alteration in Upper Cretaceous granite are investigated by core logging, mineralogical study, geophysical logging and hydraulic testing. This report describes the results which were obtained in the interval from the ground surface to 500m at Tono area in the central part of Japan.
The results are summarized as follows ;
(1) Fractures are classified into four groups on the basis of fracture pattern; Planar group (P), Irregular group (I), Curved group (C), and Stepped group (S).
(2) Most of fractures belonging to P group and S group have filling materials composed of chlorite, calcite and sericite. Some of the fractures belonging to I group have been filled with materials composed of montmollironite, sericite and chlorite. Fractures of C group hardly have filling material.
(3) Some of alterated fracture zones are consisted of P group fractures.
(4) As a result of analysis on the fracture pattern and alteration pattern, three segments are recognized; Segment I (from 16.8m to 300m), Segment II (from 300m to 420m), and Segment III (from 420m to 500m). Especially, there are marked differences in fracture pattern and alteration pattern between Segment I and Segment III.

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Engineering geological map is generally regarded as a practical expression of a three dimensional geological model which is made from the various geological information for construction works. Users of the geological map reconstruct an another model on the basis of the given information on the map. Finally, the geological information is converted into engineering forms for designing.
Considering this utility environment of the engineering geological map, it must have a function as a information medium about geological information from geologists to designers. To enable designers to obtain reasonable engineering information from the model, it is required that above-mentioned two models coincide with each other.
Practical methods to get the coincidence of the models are as follows; (i) establishment and standardization of mapping algorithm, (ii) expression of The rightfulness or fuzzyness of the information, (iii) standardization of expression forms of the information on the engineering geological map.

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