Thermal infrared imaging tests were done utilizing an airborne and a land thermal infrared scanning system in the Kusatsu-Manza geothermal area, central Japan. The results are presented and some interpretations are given.
The area is situated geologically in a part of northern Fossa Magna region and characterized by andesitic volcanic activity successive from Neogene Tertiary to Recent. Many geothermally anomalous spots developed in the area are more or less related to the active Kusatsu-Shirane Volcano which is quiescent after the explosion of 1937-39.
Thermal infrared imaging flight was made on Aug. 19th, 1972, obtaining early morning-imageries of the major geothermal spots in the area. The imagery of the Sesshogawara geothermal spot was analyzed by a color reduction system and it was correlated with the heat discharge map of the spot previously obtained by the snowfall calorimetric survey. A consideration is made in view of knowing the limit of detectable lowest heat intensity by thermal infrared imagery on the basis of the result. Also explanations are tried on remarkable“anomalous”surface temperature patterns shown on the imagery.
Land thermal infrared imaging test was done during Aug. 31st to Sept. 2nd, 1972, at the“Karafuki”geothermal spot in the Manza area. Daytime and nighttime thermal infrared imageries are presented and a discussion is made comparing both data in relation to the use of thermal infrared imagery for geothermal detection.

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The feasibility of the tree species discrimination and tree vigor discrimination were examined by using of Chromaticity measurement of IR color film.
The chromaticity of color image was determined from measuring spectral transmit-tance by the microspectrophotometer, and displaied on the CIE 1960 UCS diagram.
Discrimination was based on the differences of the chromaticities, and discriminant functions to discriminate tree species were obtained.
The result shows that discrimination of tree species is relatively easy in the case of some tree combination, and that discrimination of the tree vigor gradation is not feasible, by the chromaticity measurements.

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The definite investigation method of the debris volume derived from the bare mountainside has not been established. Around the Ashio desolate mountainous area, photogrammetric comparative measurement of surface height of some model zones settled on mountainside is carried out through the large airphotographs taken at intervals of about one year by helicopter. Mean deviation value of height of each model zones is applied to all mountainside classified to each type beforehand by photointerpreta-tion to tctalize the produced volume of debris. Though the measurement error is estimated as about ±3.6cm, this method is considered to be effective for this purpose at nowaday.

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