The linear fractures so called by this paper are a series of images of straight lines on the LANDSAT's photoes, and most of them are caused by tectonic activities, such as fault-controlled river systems, offset streams and ridges, subsidence lake basins and grabens, deviational alluvial fans, straight seashore lines and somemicrofractures which may result from the recent crustal movement. Therefore, the word "fracture" can not be limited to geological faults.
We inlay and interpret 123 photoes from LANDSAT-1, 2, 3, in the region between E 104°-122°and N 34°-41°, which covered 1.36 million km². The photoes used by us are coarse and black-white, so there are errors of 6-7mm in our inlay. The density slicing had been done in part of the typical photoes. In order to check our interpretation, some field examinations have been carried out. We discover that the activities of all kinds of the fractures in the latest geological time were shown into two aspects:
1. Continuity. Most of the fractures activities occur along the old faults of pre-mesozoic era.
2. Originality. Part of the fractures originated in the Neogene period, especially in the Quarternary era.
All the characteristics as mentioned above are eyecatching on LANDSAT photo images.
In the course of our analysis, we find that in the whole region of North China, various typies of fractures are shear, particularly in recent tectonic stress field. In spite of their criss-cross each other, they are in order and fall into three groups of conjugate systems, e. g. EW/NS, NNE/NW-NWW, NNW/NE-NEE. Finally, the authors have tried to find out the relationship between the seismicity and the linear fractures.