摘要
By far,there have been only a few neotectonic studies of the Qianliyan Uplift. In recent years,we have gathered multi-channel seismic data covering the whole uplift. After interpretation,we recognized three major Quaternary faults/fault zones. They are the South Boundary Fault Zone(SBFZ),F3,and F2 from south to north,respectively. These faults are almost parallel each other and trend northeastward.The SBFZ on most sections has been active at least since the middle Pleistocene; some segments of SBFZ are active since the Early Pleistocene.The latest activity of F2 is in the Early Pleistocene while that of the F3 is in the Middle-Early Pleistocene.The deformation intensity of SBFZ varies along strike and is well correlated with the curvature of the fault trace, that is,big curvature correlates with big deformation intensity. This correlation implies a NW maximum principal stress that may be caused by the relative convergence of the Philippine Sea Plate and the Euro-Asia Plate.The map of earthquake epicenters(≥MS 3.0)shows that there are several earthquakes distributed roughly along the SBFZ.Considering the relative intense deformation of SBFZ,we propose that great attention should be paid to the seismic risk of SBFZ.