LEGEND 
EH Extracted Area (Score over 77) 
BH Londslide occurred already 
  
Contour line 
  
  
  
  
avis 
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Fig.4 Distribution of extraction area. 
Gray area is area of getting score over 77. tt is a great 
possible to find new landslide points in gray area. 
3.3 Attempt to renew the landslide distribution 
information 
  
Fig. 4 shows the results of 3.2 including those 
of already occurred landslide areas. But the 
possibility that new landslide may occur is 
considered at other than the areas where landslide 
occurred already. Therefore, in extracting new 
areas of landslide, we overlaid the landslide point 
information extracted by the analysis mentioned in 
the above. with raster . data of topographical 
information (information in the form of image), and 
extracted the areas on the display by visual 
interpretation. We attempted to renew the landslide 
point information by overlaying the new landslide 
points thus extracted onto the already occurred 
landslide areas. 
4, Conclusion 
We obtain the following findings through this 
study. 
(1) It is useful to introduce GIS to support the 
renew of landslide distribution information which 
needed much time and labor in the past, Tor. the 
following reasons. 
1) Simultaneous evaluation of factor information 
2) Free retrieval of geographical information 
3) Quantitative and rapid grasp of complicated 
polygons. 
(2): To add: weight to factor . information - in 
evaluating the overlay result means to establish a 
quantitative judgment standard. 
(3) In this study, we used only the information 
which has been arranged as plane information. Even 
by using the plane information, it is possible for 
us to obtain support information to specify the 
landslide area by utilizing the various function of 
GIS. 
654 
5. Epilogue 
In this study, we discussed the application of 
GIS ‘to the extraction of landslide points and to 
the renewal of landslide distribution information. 
GIS is effective for quantitatively analyze the 
geographical information which expands over a wide 
area and which has complicated shape. The 
effectiveness of GIS will become higher as there 
will be more advancement in the study of spatial 
analysis method such as pattern recognition. 
Lastly, the following matters are pointed out as 
the future problems: 
(1) It is necessary to introduce objective and 
quantitative method in making judgment for 
attribute information. For this purpose, it is 
desirable to establish the analysis method Jointly 
using the statistical method such as quantity 
theory. 
(2) It takes much time and labor to construct the 
database. When the future of GIS is considered, it 
should be urgent to improve the efficiency of data 
acquisition. 
Bibliography 
S. Akabane, H. Kato: Geology of Takada-seibu 
district, with geological sheet map at 1:50000, 
Geology Survaey Japan, pp. 78-82 (1989) 
The Public. Works Research! Institution, Niigata 
Institution: Landslide Distribution Map (1:50000) 
(1969) 
M. Setojima, K. Shiraishi and M. Mori: Extraction 
of landslide areas using SPOT data and updating of 
landslide distribution map, Journal of Japan 
Society of Photogrametry and Remote Sensing, Vol. 
30, No. :3, pp. /-15:01991) 
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