A DISCUSSION ON THE GROUND SUBSIDENCE AND THE GENESIS OF GROUND FISSURE IN XI'AN CITY
Yi Xuefa (Seismological Bureau of Shanxi Province)
By using the dynamic data of the water level changes in deep wells and the data of ground deformation at bench marks, as well as the data of the fissure activities, which were observed for recent ten odd years in Xi 'an city, the genesis of the ground fissure in the Xi'an urban area is analysed. It is suggested that the generation and growth of the fissure are closely related to deep-well water pumping. As the water level declines in the deep wells (150-300m) at the north and south sides of the fissure are much different in amplitude, the ground subsidence and deformation o'f both the sides are non-uniform. Therefore, the ground fissure of interest is caused by the non-uniform local ground subsidence.