A DISCUSSION ON GAOQIAO FAULT AND ITS ACTIVITY

The active fault is a core factor for evaluating the qualification of engineering sites, Gaoqiao fault is right an important fault zone which is being worth paying attention to for the Three Gorges Project.Its distribution is characterized by multi-segment en echelon distribution, showing characteristics of horizontal twisting motion and thrust motion.Its new activity has 5 evidences:1.The Longhuiguan earthquake (M_s=5.1) on May 22, 1979, is related with the fault;2.the landslides along the fault zone are dense to be in belt, being 11 times larger than the average surface density in the area;3.the abnormal coefficient (K) of the river crossing the fault shows a sudden variation;4.The gas-mercury measurements crossing the fault show anomalies;5.By the neochuonologic (SEM) determination, the latest activity of the fault was in Upper Pleistocene (Q₃).