Detection of Puduhe fault in Yuxi basin of Yunnan by seismic reflection method

A scheme is described for seismic prospecting implemented under complicated conditions such as thick overburden, dense population and strong background noise. This is illustrated by detecting Puduhe buried fault located in Yuxi basin using seismic reflection method, in which a spread geometry with a large vibrator, small receiver intervals, long arrangement and high fold number was selected in accordance with the real site conditions. The seismic time section with higher SNR obtained in this case clearly reveals the attitude and scale of the Puduhe fault. Results show that the maximum overburden of Yuxi basin (N+Q) is 820 m. The surface of the basement rock changes abruptly in west, while gradually in east, showing a dustpan-like geometry with a strike of NNE--SSW. Puduhe fault is divided into two branches across the western Yuxi basin. The main fault has a strike of N20°E, dipping to east with an apparent angle 75°—80°. The fault scale increases gradually from south to north. The throw of the basement is 40 m near Dayingjie town located at the south of the basin, and increases up to 280 m near Jiulongchi town at the north of the basin. The Puduhe fault, crossing western Yuxi basin, dislocated the middle and upper strata of Pliocene series, Neogene system.