ON THE QUADRANT PATTERN OF STRAIN DISTRIBUTION OF THE TONGHAI AND DONGCHUAN EARTHQUAKES, YUNNAN PROVINCE

In this paper, the strain distribution around the epicentral regions of the 1970 Tonghai Earthquake, M=7.7 and the 1965 DongChuan Earthquake, M=6.5, Yunnan Province, has been studied. It is found that the tensional and compressional areas of the earthquakes distributed themselves in separate quadrants. Before the DongChuan earthquake, there were tensional and compressional areas in the block west of the earthquake fault. The phenomenon has been interpreted on the basis of the elastic rebound theory and its significance in earthquake prediction discussed.In addition, the authors also give a brief account on the possibility of observing the phenomenon of quadrant pattern of strain distribution with respect to the time range before the earthquakes and the areal extent around the epicenters.