活断層との対比によるリニアメント抽出を目的とした画像強調効果の定量評価

Abstract

Interpretation of the geologic structure of the earth's surface using satellite data reflecting the subsurface fractures in the target area is the significant method for the exploration. Fracture analysis would be an unusually simple and valuable tool for understanding the structure in subsurface. This study is aimed at the analysis of relation of the earth's surface character and data processing methods using extracted lineaments from Landsat TM VNIR data. It is well known that the lineament patterns are the significant features to indicate the historic results of structural motion. In this paper, two VNIR Landsat TM data were chosen from the two categories of surface character, vegetated mountainous, and vegetated flat areas, to apply three types of digital filter, such as median (MD), bidirectional high frequency component enhancement (TY), and omnidirectional high frequency component enhancement (OM) . Types of the filters were selected from the points of enhancement and preservation of the edges contained in the original images. Four images, Original, MD, TY, OM, were generated in each area. Using these enhanced images, the lineaments were extracted and analyzed statistically. As the results, images of median filter in both category area preserve the lineament pattern of non-enhanced original images, but bidirectional and omnidirectional high frequency component enhancement images do not preserve the original image's character. The relation between lineaments and active faults existing in each study area, we can clearly find those active faults as lineaments on the images. Apparently, northward active fault running from Yoneshiro river can easily be recognized in each processed images of studied Noshiro area. Active faults running around Mt. Iwaki can also clearly be seen as lineaments in Hirosaki area. The matching ratio among active faults indicate that omnidirectional high frequency component enhancement images are in maximum in both studied areas.