Active tectonics along site and neighborhood of west route of South-to-North Water Transfer Project in China

The first stage project of the west route of South-to-North Water Transfer Project is located in Bayankela block interior of the eastern Qinghai-Tibet Plateau. The boundary of Bayankela block is all the giant strike-slip or thrust fault systems, which have intense activity; and the boundary belts are the primary sites of the accumulation and release of stress resulted from the blocks movement. The fault activity is weaker in Bayankela block interior than that of the boundary belts. Partial faults of Gande-Aba fault system, Seda-Luoruo fault, and Kangle fault, etc., were active at one time since Late Pleistocene epoch. However, they have weaker active intensity than the boundary belt. The average displacement rates of the block boundary faults in the late Quaternary Period were generally more than 7 mm/a; the maximum value was up to 18 mm/a, and the minimum one was 1-2 mm/a; however, the slip rate of the most primary active fault at the raceway vicinity is only 0.18 mm/a. In general, the crust of the project site is relative stable. The maximum dip-offset of the faults needed to be protected for the project during useful life has been deduced; for example, for the Aba basin north marginal fault and the Shunhe fault the maximum value is 0.67 m and 2.62 m, respectively.