Contemporary Tectonics of China

摘要

Seismic data and LANDSAT imagery in western China have been investigated in detail. Fault plane solutions of earthquakes that occurred in the past ten years were derived from polarities of first motions of P waves and S waves. Numerous faults and fault systems were identified from LANDSAT imageries. In particular, a new strike-slip fault (the Po Chu fault) and numerous normal faults in the Tibetan Plateau were discovered. Lineaments on the imagery were interpreted as late Cenozonic faults primarily based on linearity, sharpness of a scarp, and presence of a topographic, tonal or textural difference across the lineament. Characteristics of different types of faulting can be inferred from their geomophology. Normal faults are indicated by sharp, broken, and an echelon fault traces. Major strike-slip faults are characterized by long linear traces. Evidence for recent motions along such faults is provided by sharp offsets in the Quaternary alluvium, ponding of streams, and offset of streams. Analysis has shown positive correlation between epicenters of strong earthquakes and major faults in the southern Tien Shan and Tibetan regions.