DEVELOPMENT RULES AND MOVEMENT CHARACTERISTICS OF EARTH FISSURES IN CHINA

Earth fissure is one of main geological hazards in China. By 2015, 5002 earth fissures were discovered in more than 1, 500 localities across 22 provinces. These earth fissures caused huge economic loss. Based on a series of geological investigations including in surveying, mapping, trenching, drilling and monitoring, the spatial distribution and development rules of the earth fissures are summarized, and the movement characteristic of the earth fissures are revealed. The results show that the earth fissures mainly distribute in North China and South China, especially in the Fenwei Basin, Hebei Plain and Yangtze River Delta. The giant earth fissures, longer than 1 km, mainly distribute in the Fenwei Basin and Hebei Plain. These earth fissures exhibit the following five regular patterns: clustering along fault zones, distributing along geomorphic boundaries, appearing on the edge of subsidence areas, dispersing in loess collapsible area, and centralizing in larger and medium cities. The movement characteristics of the earth fissures can be divided into four types: tension type, tension-shear type, shear-tension type and shear type.